Cat Aids

How does Feline Immunodeficiency Virus (FIV) compare to Human Immunodeficiency virus (HIV)?

Feline immunodeficiency Virus (FIV) has similar building blocks and is related to Human Immunodeficiency Virus (HIV), but very importantly, it cannot be passed between cats and humans. The virus can also not be transmitted from cats to dogs. Both FIV and HIV viruses share a similar pattern of disease progression. Both viruses are classified as Lentivirus, which means they have a long period of showing very few clinical signs during which time the immune system deteriorates. Eventually Acquired Immunodeficiency Syndrome (AIDS) develops and this is accompanied by opportunistic infections, systemic disease and cancer. The close relationship between FIV and HIV has meant that FIV has been used as an animal study model to better understand HIV in humans.

FIV was first described in domestic cats in 1987 but data suggests that wild cats may have been affected for much longer. It has been found that the majority of lions are infected with FIV but few show clinical signs.

How is FIV transmitted?

FIV is passed between cats by contact (also referred to as horizontal transmission) and not from a mother to her unborn kittens. Male cats that have not been neutered and living outdoors have been found to be most at risk. The virus is found in the saliva of infected cats and is most commonly transmitted through bite wounds with fighting. Although it is also found in the semen of infected males, sexual transmission, unlike in HIV, is uncommon. The true prevalence of the disease is not known because testing is completely voluntary. The prevalence is highly variable and depends on the age, gender, lifestyle, physical condition and geographic location of the cat. 

What are the symptoms of Cat Aids?

Similarly with humans, infection with FIV virus does not immediately lead to full blown aids. Acute FIV infection is often associated with mild clinical signs, which usually go unnoticed by pet owners. Cats may have occasional fever, decreased white blood cell counts and enlarged lymph nodes. High concentrations of the virus can be detected in the blood as early as two weeks after infection. Initial infection is characterised by a prolonged asymptomatic phase, where no clinical signs or other symptoms are seen and there is progressive weakening of the immune system. The course of the disease following infection is dependent on a number of factors. These include the age and health at the time of infection, dose and rate of infection, dose and route of virus infection, viral strain, presence of other infections at the same time, and the immune status of the animal.

Weight loss is the most common clinical finding in symptomatic cats, followed by fever, infections of the mouth, dehydration, runny nose, conjunctivitis and abscesses. Concurrent infections with other viruses are also often identified.

How is FIV diagnosed?

The diagnosis is made in the veterinary practice by means of a blood test. This test is quick and accurate. It is important to test cats before introduction into a new household, as well as at regular intervals after that. Most cats will produce antibodies 60 days after infection so if exposure is suspected, testing should be done two months later. Antibodies, the body’s soldier cells which fight the infection, can be passed on from the queen to kittens in the colostrum, which is the first milk. This provides passive immunity to the kittens and they will test positive. This however does not mean they have the disease but will be protected from getting the disease for a short period. The development of the FIV vaccine has also complicated the diagnosis, as vaccinated cats will most likely test positive to the blood tests done in house at the vet. It is therefore very important for the veterinarian doing the test for FIV, to have a good understanding of the history and previous treatment of your cat.

How is FIV prevented?

The majority of infections occur through bite wounds sustained when fighting with infected cats. Generally, cats in households with stable social structures where housemates do not fight are at low risk for acquiring FIV infection but exceptions do occur. In multi-cat households, FIV positive cats should ideally be isolated and kept in a separate room or separately from the other cats.

The exposed virus (outside the cat’s body) is easily deactivated by routine hygiene procedures so disinfection and cleaning are important in controlling the spread. It is important to regularly clean and discard litter box contents as the virus can survive in dried biological material, such as stools, for several weeks. Cats should have separate feed and water bowls. Introducing additional cats into a positive household is discouraged because it disturbs the existing social structure and may result in increased aggression between animals.

In the animal hospital environment, all blood donors are tested regularly to ensure a negative status. Hospitalised infected cats are isolated due to their compromised immune status.

It is recommended that any new cat introduced into a household, should be tested prior to introduction. It is recommended that testing be repeated after 60 days as the disease has a long incubation period. Should a new cat test positive, then all the other cats in the household will have to be tested as well.

Although a vaccine has been developed, it has not been totally effective in preventing infection as there are several different strains of the virus. This does not mean one should give up on vaccinating. If your cats happen to be exposed to the strain used in the vaccine, it means they will enjoy protection.

Management of positive cats

General recommendations for the management of FIV positive cats include confinement indoors, stress reduction, good quality food and regular veterinary visits. There are a few antiviral drugs available, which have been found to help FIV infected cats although the study of their success has been quite limited. It is important to try and keep secondary infections under control and avoid drugs such as corticosteroids that may further compromise the immune system.

What is the prognosis of positive cats?

Testing positive to FIV is not necessarily a death sentence but it depends on the health of the animal when they are tested. Some cats can survive up to three to four years after testing positive. Keeping the positive cat isolated, providing good nutrition and managing secondary infections is vital in ensuring survival and maintaining health for as long as possible.

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Feline Leukaemia Virus (FeLV) infection in cats

Introduction

Feline leukaemia (FELV) is a disease of cats caused by a virus called a retrovirus. It is called a retrovirus because of the method it uses to replicate inside the cat. It is the same type of virus as the human immunodeficiency virus and although there are a lot of disease similarities, several studies have shown that the disease is not transmissible to humans. FeLV is one of the most dangerous diseases that affect cats and is a major cause of death in cats. Fortunately the prevalence of the disease has decreased in recent years due to the use of vaccines against the disease and the ability of vets to diagnose the disease early and accurately.

How do cats contract Feline Leukaemia?

The disease is more prevalent in cats between one and six years of age and is more often seen in males than females. The virus is present in high quantities in the saliva of an infected cat, but also in smaller quantities in the stool and urine. The virus gets transmitted through cats biting each other as well as through grooming each other. In a few circumstances it can also spread between cats by sharing food and water dishes. It can also be transmitted from the mother to a foetus inside the womb, as well as through milk from the queen to the kitten once the kittens are born. If one considers the way the virus spreads it should be clear that multi-cat households will be more affected than single cat households. Cats that roam outdoors are also more exposed in terms of getting into contact with other infected cats.  If your cat is infected with Feline Leukaemia at an age younger than 8 months it is most likely that the disease was contracted from the mother. If a cat gets sick with Feline Leukaemia after 8 months of age it is more likely that the infection was contracted from other cats in the household or roaming cats.

What does Feline Leukaemia do?

Not all cats that get infected with the FeLV virus develop severe disease. With initial infection the cat’s immune system may fight the virus and get rid of it completely. In other circumstances the cat’s immune response is not adequate and the virus infects tissues like lymph nodes and the bone marrow. The virus can lie dormant in these cells for years, not causing disease but if the cat is stressed or the immune system challenged, the virus may start replicating and cause full blown and serious disease.

There are four different subgroups of the virus causing different disease processes in the cat’s body. A cat can be infected with one, two or all four of the different types. The different types are called FeLV-A, FeLV-B, FeLV-C and FeLV-T. FeLV-A is found in almost all naturally infected cats and tends to be less severe disease than viruses of the other subgroups. FeLV-B causes cancer in cats and occurs in about 50% of cats with FeLV. FeLV-C affects the bone marrow and red blood cells and can cause severe anaemia or low red blood cell count. FeLV-T causes a severe drop in immunity because it destroys white blood cells called T-lymhpocytes which play an important role in the defence mechanisms of the cat’s body. 

The clinical signs which cats will show depend on what type of subgroup virus it is infected with. The signs seen most often are loss of appetite or anorexia, depression, weight loss, unexplained fever, poor coat, infections in the mouth like gingivitis (or gum infection), eye infections, diarrhoea and enlarged lymphnodes. Typically the virus causes a slow deterioration of the cat’s health over a number of months. Owners will often notice that the cat will be more listless, skip meals more often and show slow weight loss. The cat will have minor ailments more often due to the decreased immune system and will need to be taken to the vet more often. These symptoms will alert the vet to test for this virus.

How is Feline Leukaemia diagnosed?

Fortunately we live in an age where there are much more efficient methods to diagnose FeLV now than in the past. It can be done with a simple test at the vet, called a FELV snap test or Elisa test. All that is required for this test is for the vets to take a small blood sample from the cat and do the test with the results being available within a few minutes. If the results are not clear or definitive or if one needs to know what stage the infection is in, another test can be done at a laboratory for which blood needs to be sent away. This test is called an IFA or immunofluorescence assay test. It is important to realise that other common infections needs to be ruled out first. A full blood count and organ function test will often be done at the same time as  this will provide the vet with information on how the virus has affected the different body systems at the time of making the diagnosis. It will also serve as a reference point for future monitoring of the disease to see how the virus progresses and may serve as a prognostic indicator.

Treatment options for Feline Leukaemia

Sadly there is no cure for full blown Feline Leukaemia. Cats can only be treated symptomatically and made as comfortable for as long as possible. Infected cats will need extra attention and need to be taken to the vet more frequently for regular health checks. Their basic health care like deworming, flea treatment and vaccinations needs to be done regularly. With regular vet visits the vet can pick up any problems early and start treatment as soon as possible. Regular blood tests should be done to determine deterioration as early as possible. It is recommended to visits the vet at least every 6 months if your cat is diagnosed with FeLV infection.

Because the immune system of affected cats is compromised, these cats may often require treatment with antibiotics for secondary bacterial infections. It is important to give antibiotics for at least 7 to 14 days to prevent the build-up of antibiotic resistance. Blood transfusions can be given to anaemic patients and chemotherapy is an option for cats with cancer. It is important to remember that these treatments do not provide a cure, but alleviates the symptoms of the disease to some extent and make life more comfortable for infected cats. Unfortunately 85% of persistently infected cats die within 3 years of being diagnosed.

Infected cats should always be placed on a good quality diet. Never feed a raw diet as this can introduce infections. They should be kept indoors to protect them from any infections but also to prevent the spreading of the disease to other cats. FeLV infected cats should be kept as stress free as possible. They also tend to do better in a single-cat household rather than in a multi-cat household. Never introduce a new cat into the household with an already infected cat, as this may lead to increased stress and fighting and transfer of the disease.

How to prevent healthy cats from getting infected with FeLV?

The most important method to prevent infection is to keep cats indoors and not let them roam. There are also vaccinations available against FeLV. Before having your cat vaccinated, you have to have them tested for FeLV first. When introducing a new cat into the household, always have them tested for FeLV beforehand. When one of the cats in a multicat household is diagnosed with FeLV, have all the cats tested and vaccinate all the unaffected cats. There has been no benefit shown to vaccinate an already infected cat. If at all possible it will always be beneficial to separate an infected cat from other cats.

Feline Leukaemia may be a terrible disease but it is by no means an immediate death sentence when a cat is diagnosed with the disease. With modern advances in veterinary medicine and care, infected cats can live a good quality life for years after they were initially diagnosed.

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The Hype about Hyperadrenocortism

Hyperadrenocorticism, or Cushing’s Disease, is a condition whereby the level of cortisol in the body is too high.  It is a condition which is also found in humans and the name Cushing’s Disease or also commonly known as Cushing’s Syndrome comes from Harvey Cushing, who in 1912, was one of the first physicians to report a patient affected with excessive cortisol hormone also otherwise known as glucocorticoid.

Cortisol is a hormone that is present normally in the body and it usually increases to a small degree in response to stressors such as illness, environmental changes or fear.  Some people call it the “fight or flight” hormone. Cortisol is a catalyst for different events to occur, such as the release of cells which fight infection and a release of sugar from the muscles in case the animal needs to utilise these stores.  Cortisol helps the animal to cope with stressors and is necessary for normal function.  Its production is closely regulated by the body’s physiological processes, so that the animal can respond as needed and remain in balance with its environment.

The pharmaceutical industry has managed to produce drugs which are almost identical to the cortisol which is produced by the body naturally. The use of these drugs is very common, because patients respond so well to their positive effects. However as with everything in life, – too much of a good thing, is not a good thing anymore. Administration of these medications can actually lead to Cushing’s syndrome as well. This is known as an exogenous cause. We will not concentrate on this type of cause on this article but rather on the internal or endogenous cause of Cushing’s disease. Cushing’s disease is a disease that occurs fairly commonly in dogs but rarely in cats.  Female dogs are slightly more predisposed than males, and it usually occurs in animals older than six years of age.  It is seen most frequently in Poodles, Dachshunds, German Shepherds and terriers of different kinds.

Cushing’s Disease is a complex syndrome with a large range of symptoms.  To fully understand it, one must first understand the normal physiology of the animal.  In every dog and cat there is a series of events that occurs to produce cortisol.  One can imagine a factory line within the body, and it starts with an area in the brain called the hypothalamus.  This region of the brain produces neuro hormones which go to the next site in the line, the pituitary gland.  The pituitary gland is a tiny gland sitting at the base of the brain which has an amazing influence on many of the body’s normal functions or homeostasis. The pituitary gland is stimulated to produce another hormone which goes to the adrenal glands which are situated very close to the kidneys. The adrenals are the final stage of the factory line and they produce cortisol.  A problem can occur at any of the points along the line.   Unlike at a factory, the cells do not go on strike and stop working.  Usually the problem is that the cells overwork (for example if a tumour is formed) and so too much of the hormone produced at that site is released.   (Wouldn’t it be nice if this occurred on an industrial level?!)  The area that overworks increases the production of hormones further down the line.  It also decreases the hormones produced before it due to negative feedback (the manager of the factory phones to tell the workers to take a break, enough is being produced!)

The main signs of Cushing’s disease include an increase in appetite (polyphagia), as well as an increase in water consumption (polydipsia) and urination (polyuria).  Another common sign is an enlarged abdomen, giving the animal a potbellied appearance.  This is due to weakening of the abdominal muscles and the deposition of fat in this area, as well as an increase in size of the liver internally.  Cushingoid animals often have a symmetrical hair loss over the body and the skin can become quite dry and thin.  Other signs include lethargy, acne, weakness and a tendency to bruise easily.  Bitches can fail to cycle normally, and males may show a reduction in size of the testes.

Roughly speaking about 70% of tumours occur at the pituitary gland, and only about 30% at one of the adrenal glands.  It is important to establish where the tumour has occurred as it affects prognosis and treatment.  This can be done with a series of blood tests and also ultrasound scanning (the tumours cannot however always be seen).  The main tests performed are the Dexamethasone Suppression Test and the ACTH Stimulation Test.  These tests mimic the hormones produced by the body to assess which parts of the factory line are implicated.  Prognosis for pituitary-dependent Cushings is usually good, and for the adrenal-dependent form more guarded.

For both types of Cushings the treatment is lifelong oral medication, but it tends to be more effective in pituitary-dependent Cushings.  There are mainly two types of drugs being used to treat Cushing’s disease. The one drug acts by destroying the cells of the adrenal gland so that production of cortisol is reduced, thereby "taking workers out of the production line".  Once these cells have been destroyed they are gone forever, thus requiring cortisol replacement in the form of tablets, if too much of the adrenal glands are destroyed. The other drug acts by competing for the building block enzymes which are needed by the cells of the adrenal glands to produce cortisol thereby "reducing supplies of raw materials needed for manufacturing, resulting in less output". This drug tends to have less side effects but can be quite significantly more expensive. The choice of which drugs to use will depend on the condition of the animal, how advanced the state of the disease is and cost of medication.  Side effects  of medication may include vomiting, diarrhoea, lethargy weakness and loss of coordination.  Treatment for adrenal-dependent Cushings can also involve surgical removal of the cancerous gland.  There is a risk that the adrenal gland tumour will spread to other parts of the body before surgery takes place, which would markedly worsen prognosis. It is important to note that if the route of oral medication is chosen that it is considered chemotherapy similar to cancer treatment. The medication should be handled with care and preferably with latex gloves, because some of the medication may be absorbed through human skin and will have the same effect in humans as in animal that it will destroy the cells of the adrenal gland.

In certain cases patients who are diagnosed with Cushings are not very ill and if this is the case then the vet may decide that treatment can be optional.  However, some animals suffer more than others and all animals with Cushings are at an increased risk for developing Diabetes and bacterial infections.  When treatment is commenced it is important that the patient visits the vet frequently in the beginning to assess how effective the dosage is at controlling the syndrome. Over-medication can have serious side effects because of the destruction of the cells of the adrenal glands.   Medication may need to be adjusted over time to for the animal to cope optimally. Long term treatment may be expensive depending on the size of the dog.

The prognosis for Cushing’s disease when treated is good, especially if the tumour is of the most common type.  The average survival time for a dog after diagnosis is about two years.  This may not sound impressive but is important to note that most dogs are already middle aged or older at the time of diagnosis. 

As with the diagnosis of any serious lifelong condition in a pet, the owner must think about what he or she is prepared to commit to, in terms of costs and administration of medication.  Choices like these are highly personal and there are no “one size fits all” options for treatment with this condition.  The treatment of Cushing’s disease is however, usually very effective and rewarding.  Like a factory, if management is consistent and prepared to tweak points along the line, then production will be efficient and correct. In cases like these the factory will perform at optimal levels and the patient may continue to live a normal and happy life.  

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Diabetes Defined

The pancreas is an organ in the body which is closely associated with the segment of intestine that leaves the stomach.  The pancreas releases enzymes involved in digestion as well as hormones with specific functions.  One of these hormones is insulin.  Insulin is released from the pancreas in response to the intake of food, especially carbohydrates and to a lesser degree fats and protein.  Insulin circulates in the bloodstream and facilitates the uptake of the ingested nutrients into the body’s own stores of energy.  

Diabetes mellitus occurs either when the pancreas cannot secrete sufficient insulin; or when the body does not respond to the released insulin that is released by the pancreas.  This means that the sugars and nutrients consumed are not taken up by the body efficiently.  They remain in the blood for a longer period of time than is normal (hyperglycaemia) and are excreted in the urine (glucosuria).    

Diabetes mellitus is a disorder which is seen at a rate of roughly one in every two hundred and fifty dogs or cats.  There are large differences in the way that the disease is presented between these species.  Virtually all dogs suffer from the insulin-dependent form; whereby insulin is not produced and must be administered.  In contrast, about fifty percent of diabetic cats have the non-insulin dependent form, whereby the body is resistant to the insulin produced, so it does not produce the physiological effects that it should.

The cause of diabetes is multifactorial.  It is more common in older animals and often occurs in association with another disease or condition such as bacterial infections, pregnancy, Cushings syndrome, kidney or liver failure.  In dogs diabetes appears to have a genetic component, with some breeds being more predisposed than others.  These include Miniature Poodles, Dachshunds, Schnauzers and Beagles.  It can be immune-mediated in some cases, where the body attacks its own cells that are necessary for insulin production.  Pancreatitis (inflammation of the pancreas) is also commonly involved in the induction of the disease in both cats and dogs.  

Feline diabetes is very often associated with obesity.  The risk of diabetes is one of the main reasons that obesity in pets must be avoided.  Frequently, in cats, and more rarely in dogs, the diabetes that is diagnosed and treated is only a temporary condition.  A stressor can create a state of high blood glucose which then suppresses insulin release.  This can become a vicious cycle.  However, when insulin is administered and blood sugar levels return to normal, then further treatment is unnecessary.  This can only be determined retrospectively after treatment has been initiated.

The main signs presented in the diabetic animal are an increased appetite for food and a greater than normal thirst for water; increased urination; and weight loss.  Cats usually are thin and their grooming is decreased so the coat appears rough and can seem to be shedding excessively. In severe cases cats may present with weakness, staggering and collapsed limbs.  Bladder infections are common due to the presence of glucose in the urine, which encourages the growth of bacteria.   Wound healing can be delayed.  With cases of prolonged disease animals may develop cataracts, which may lead to blindness
Treatment for diabetes is the administration of insulin.  Dogs generally respond better to insulin derived from pigs, and cats to insulin from cows.  An overdose of insulin leads to low blood sugar or hypoglycaemia, which causes weakness and shivering, and in extreme cases, seizures.  The dose of insulin required varies from animal to animal and the best way to ascertain the ideal dose is by performing a glucose curve.  This involves checking the blood glucose every two hours over the course of one day and putting the values into a graph format to assess the fluctuations.  The aim is to adjust the amount and frequency of feeds with insulin administration to avoid dips and crests in the curve as much as possible.  Initially, glucose curves should be made every two weeks until the glucose levels are effectively controlled by the dose of insulin given.  It can take up to six months to find the correct dose and timing of insulin administration.    

 Insulin can be given by the owner in a special insulin syringe.  Insulin must be kept in the fridge and must be given at the same time every day.  Routine is very important in the management of diabetes, with feeding times (the intake of calories) and the timing of treatment being kept constant as much as possible.  There is another drug available which helps to control diabetes and can be given orally to some cats, providing that they are otherwise healthy.  It is not given to dogs.

The management of diabetes involves other factors besides medical treatment.  Keeping the diabetic animal lean is a priority as obesity can lead to worsening of the condition.  A diet that is low in calories and high in fibre is ideal.  Complex carbohydrates slow down absorption of sugar, and minimize blood sugar fluctuations.  Veterinary prescription diets are readily available from the vet and assists greatly in the treatment and management of diabetes.

Routine exercise is also helpful in controlling blood sugar and keeping the diabetic animal healthy.  Exercise of the same duration and at the same time every day helps to maintain weight and to increase insulin sensitivity.  Taking the diabetic dog for a short walk every day is far preferable to a long walk once a week.  Strenuous exercise can lead to hypoglycaemia.  Unfortunately diet and exercise cannot be used alone to manage the diabetic patient.  Insulin administration is necessary and this treatment requires dedication and commitment on part of an owner of a diabetic animal, to be successful.

Prognosis depends on the presence of concurrent disease, response to treatment and the owner’s commitment.  Long term prognosis in cats is generally guarded, with the average survival time being two years.  Dogs can survive for a number of years after diagnosis, and similar to the treatment of diabetes in human beings, can live a relatively normal and happy life as long as the consistent treatment and management of the disease is maintained.  Once the disease has been properly diagnosed and a formal treatment and management routine has been implemented, the prognosis is quite good.  The most dangerous period is before the most efficient dosage of insulin has been found, when blood sugar is fluctuating.

Many diabetic pets respond well to therapy and with consistent and correct treatment, their quality of life is excellent.  The key to success generally lies in the hands of the owner, and how willing and able they are to give the time, effort, money and commitment needed to treat a diabetic pet.

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Cancer in pets – Part 2 of 2

The treatment of cancer in pets has become a significant part of the therapy provided by veterinarians to keep our pet population healthy and thriving. Depending on the modality used, the type and extent of cancer treated, and the size and the nature of the animal involved, cancer treatment can be very expensive. Therefore, as with any disease, the principle of prevention is better than cure holds true. Not all cancers can be prevented but there are certain types of cancers which can be prevented and others that, if treated early on, require much less invasive treatment and therapy, than cancers which are left to develop.

To understand the treatment and prevention of cancer better, one has to look at what causes cancer. Cancer is derived from the Latin and Greek word “carcinos” which means crab or crayfish. This name comes from the appearance of the cut surface of a solid malignant tumour, where the blood vessels that grow around the tumour looks like the legs of a crab which stretches out on all sides of the body of the crab. Cancer refers to an unregulated growth of cells of the body which can be brought about by a number of causes. These causes include well-known and described external causes like infections, exposure to certain chemical substances like tobacco and environmental pollutants, radiation like excessive exposure to sunlight which causes many skin cancers and poor and incorrect diet and obesity. Lesser known causes of cancer include internal causes and more poorly understood causes like hereditary proneness. External and internal causes agitate the cells of the body which can combine with existing genetic faults within cells that cause them to start growing uncontrollably. For a cell to transform from a normal cell to a cancer cell the genetic material inside the cell which regulates cell growth and differentiation is altered. External agents are often referred to as carcinogens or cancer inducing agents. These agents have the ability to change the DNA of the cells they come into contact with causing them to mutate and change character and nature, which in turn leads to these cells becoming cancerous and spread. A good example of such an agent is tobacco. Human doctors have for years warned people against the dangers of tobacco smoke because it is a well-known fact that it causes many types of cancers, most notably lung cancer. 

In most cases of cancer in animals it is very difficult to prove what caused the cancer in the first instance because there can be a combination of causes. Having said that, we know that with certain types of cancer the main culprits can be identified and, if avoided, can help to prevent cancer right from the start. A good example is cancer of the skin, like the ears of white cats or the unpigmented skin of the stomach area of dogs with short coats, called squamous cell carcinoma. This type of cancer can be prevented by daily applying sunscreen on the affected parts of the body (before any cancer starts), or alternatively putting a “sunbathing suit” on for dogs, or best of all, keeping them indoors during the part of the day when the sun causes the most harm (usually between 08h00 and 16h00). Any method used to prevent prolonged exposure to the harmful ultraviolet rays of the sun, will reduce these types of cancer.

Hormones have been proven to be significant contributors to cancer in humans and animals. Fortunately the cancers which come about as a result of reproductive hormones can be significantly reduced in animals by sterilisation. Bitches that aren’t sterilised produce extremely high levels of oestrogen and progesterone when they come on heat twice or three times a year. Over the years the body’s exposure to these high levels of hormones predisposes these animals to cancer of the mammary glands as well as severe, potentially life threatening, uterine infections. It is well documented that having an animal sterilised by removing the ovaries and uterus surgically (ovariohysterectomy commonly referred to as a spay) at a young age (before one year of age), significantly reduces the occurrence of mammary tumours later on in life. Similarly the incidence of prostatic growths and testicular cancer in male dogs are significantly reduced and even eliminated by castrating (surgically removing the testicles) of such animals at a young age.

The incidence of cancer in animals which are physically inactive and obese is also higher as a result of a weaker immune system and negative effects on the endocrine system. The endocrine system refers to many different glands in the body which ranges from small glands in the brain and abdomen like the adrenal gland, to larger glands like the pancreas. These glands secrete different kinds of hormones, which maintain the body’s different functions. Taking your dog for a regular walk or run, will not only have mental and physical health benefits for both of you, but may actually assist in preventing cancer. 

Diet forms such an important part of general health and well-being in pets that the prevention of cancer by feeding a properly formulated diet goes almost unnoticed. In humans the incidence of cancer from eating the wrong foods can be as high as 20%. For humans eating a regular helping of fresh fruits, vegetables and whole grains, reduces the incidence of cancers. Dogs are omnivores, unlike cats which are carnivores. Therefore, a properly formulated diet, which not only contains all the right nutrients in the correct proportions, but also includes added vitamins, minerals and anti-oxidants which help fight off carcinogens, can prevent cancer and help your pet live a happy healthy life.

So what do you do if you have taken all the known preventative measures and your animal still develops cancer? There are approximately 200 different types of cancer and the starting point will be to identify exactly what type of cancer your animal has and what stage that cancer is at. In nature, animals cannot afford to show symptoms of disease at an early stage because “the law of the jungle” determines that weaker animals will be “taken out” by stronger ones in the pack or by predators. This natural instinct also holds true for our domestic animals and therefore the initial symptoms of disease may go unnoticed until the disease has progressed so far that the signs can no longer be hidden. By such time the disease is usually far progressed and the prognosis becomes worse with every passing day. It is therefore absolutely vital that you have your animal checked out by the veterinarian as soon as you suspect something is wrong. Your observations and “gut-feel” about their animal is often the reason why the vet can make the diagnosis at an early stage and provide suitable treatment with a much better prognostic outcome.

External cancers which are the tumours or growth type can usually be seen with the naked eye and be attended to as soon as observed. Internal cancers which grow in organs may not be visible nor might their effects be visible until the majority of the organ is affected. It is therefore of paramount importance that your animal visits the vet at least once a year for a regular check-up and wellness examination during which the animal may also be vaccinated if needed. During this examination the vet should examine all the external structures of the body like the ears, eyes, nose and mouth, the skin and the superficial glands lying below the surface of the skin, as well as the internal organs by listening to the heart and lungs, and doing an abdominal palpation (using the hands to feel and touch the organs inside the abdomen). In certain cases a rectal exam may be needed, or certain routine laboratory tests may be performed like analysis of the urine or a stool sample examination. Many cancers have been picked up by vets during these routine yearly examinations and have been treated successfully before they blow up into full clinical disease which can either not be treated or treated at great expense with a guarded prognosis.  Not all internal cancers can be picked up during the annual wellness examination and therefore the owner’s observation of their animal’s health and well-being makes up an important part of the vet’s awareness to examine for signs of cancer.

Once the presence and type of a cancer has been confirmed and it has been staged (indicating the progression of the cancer), the vet will suggest treatment. In cases where the cancer is very far advanced, has spread to other organs, or where the prognosis even with extensive and expensive treatment may be poor, the vet may suggest euthanasia.

Treatment

In cases where the prognosis is good several types of treatment may be suggested depending on the type and stage of cancer.

Surgery still remains one of the most successful treatments for cancer. This may range from minor surgery like the removal of a small tumour under local anaesthetic to major and extensive surgery like the removal of an organ or body part. In many types of cancer surgical treatment will be combined with other modalities from radiation therapy (to “shrink” a tumour before surgery) to chemotherapy after surgery (to prevent further spread).

Even though most practices have diagnostic X-ray machines which may theoretically be used for radiation therapy, it is not a service which is available in most veterinary practices and will require you to take your animal to a specialist facility. The most common form of radiation therapy is external beam radiotherapy. Your animal will sit or lie on a couch or surface where an external source of radiation is pointed at the particular part of the body which is affected. As most animals do not sit still for extended periods of time your animal will most likely be sedated). Kilo voltage ("superficial") X-rays are used for treating skin cancer and superficial structures. Megavoltage ("deep") X-rays are used to treat deep-seated tumours (e.g. bladder, bowel, prostate, lung, or brain). Superficial X-rays can be provided through the same machines used for diagnostic purposes and the deep X-rays are provided by linear accelerators or the older type Cobalt units.

Chemotherapy refers to the use of chemical compounds or drugs to fight and kill cancer cells. Unfortunately it is very difficult for these drugs to target cancer cells only and therefore normal healthy cells of the body may also be affected, leading to significant side effects.

Chemotherapeutic drugs are available in injectable as well as tablet form. Commonly when cancer is treated with chemotherapy, a combination of both is used. The drugs given intravenously are usually injected with the aid of a drip line. As these drugs tend to be very cytotoxic (toxic to cells) they can cause significant damage to healthy tissue if not administered with great care. Therefore your animal will likely be admitted to the veterinary hospital as an in-patient for this procedure. Chemotherapy medications which are administered per mouth may require you to handle the medication with latex gloves to prevent uptake of the medication through your own skin.

Immunotherapy is where immunostimulants (drugs which boost your animals internal defence systems) are administered in certain types of cancer to stimulate the immune system to reject and destroy certain types of cancer.

Photodynamic therapy (PDT) is a form of phototherapy (exposure to specific wavelengths of light using specialised light sources) which use nontoxic light-sensitive compounds that, upon exposure to this light become toxic to targeted malignant and other diseased cells.

Complementary and alternative cancer treatments are a diverse group of health care systems, practices, and products that are not part of conventional medicine. "Complementary medicine" refers to methods and substances used along with conventional medicine, while "alternative medicine" refers to compounds used instead of conventional medicine. Most complementary and alternative medicines for cancer have not been rigorously studied or tested. Some alternative treatments have been investigated and shown to be ineffective but still continue to be marketed and promoted. It is considered to be a specialised discipline and as such may not be something you should expose your animal to unless done through a veterinarian specialising in this field.

Cancer CAN be beaten. As long as your vet has the opportunity to diagnose cancer early and treat it appropriately, your animal has the chance of living a long and healthy life.

© 2018 Vetwebsites – The Code Company Trading (Pty.) Ltd.

 

Cancer in pets – Part 1 of 2

The battle against cancer in humans is as old as mankind itself. Since veterinary medicine became a fully-fledged discipline in the previous century, this battle has been extended to animals, and more so than any other area of veterinary medicine, to our pets. Many animal owners who are confronted with cancer in their pet for the first time, are somewhat surprised to find out that cancer is as prevalent in animals as it is in humans. Once they have overcome the initial shock, they find it even more surprising that cancer in animals is treated very much the same way in animals as in humans.

As vets we often get asked if there is a higher incidence of cancer in animals than in the past. The answer is difficult to verify 100% because extensive studies need to be done to confirm such a suspicion. However two reasons why there is a heightened awareness of cancer, and why it may seem like cancer has become more prevalent, is because animals have grown older in recent decades than in the past. This is because of advancements in modern veterinary medicine, preventative medicine like vaccinating and parasite control, high-quality nutrition, as well as being protected against predators, disease and other external influences. Our domestic pets live a very protected life in our modern homes where they cannot get out and fight with other animals or get run over by motor vehicles. The other reason is because modern veterinary medicine has given us the tools to become better at diagnosing and treating cancer at an early stage. A century ago we did not have the diagnostic tools we have today, which can clearly identify all different types of cancer and determine how invasive or extensive they are at the time of making the diagnosis.

Depending on the type of cancer, the treatment modalities for cancer include surgery, chemotherapy (using medicines to fight the cancer), radiation therapy (using X-rays to treat the cancer) and alternative remedies.  The treatment modality chosen depends on a number of factors such as the type of cancer, where it is situated, how invasive it is, how far advanced it is, and what the cost of the treatment involves. In our next article we will look more into the treatment of a cancer.

Cancer can either be very visible like a lump somewhere on, or inside the body, often referred to as a tumour (which is derived from the Latin word for swelling), or can be completely invisible such as cancers of the blood.

Cancer can broadly be divided into “not so serious” or benign cancer and “serious” or malignant cancer. The differentiation depends largely on how invasive the cancer is and whether it has the ability to spread to the rest of the body and affect all the body’s systems and organs. A benign cancer is usually a cancer which grows locally, is well confined or encapsulated, can easily be removed and does not have the risk of spreading to other organs. An example of such a cancer is a lipoma, which is a cancer of fatty tissue, which can usually be surgically removed without the risk of spreading to the rest of the body. Another example is a benign adenoma, which is similar to a wart and usually appears as a small lump which grows on the skin, and which can be surgically removed without ever growing back. One thing to remember though is that even if a cancer is benign, it cannot be left without attending to it. Lipomas which are left to grow into huge tumours can become quite complex to remove surgically, and many times distort the blood supply to the area where it is growing significantly, making surgery more risky and complex. A benign adenoma which is left to grow can become a physical impairment and get damaged and bleed. Continuous irritation and damage may in certain cases lead to a benign tumour becoming aggressive or malignant.

Malignant cancer may not necessarily form a big lumpy tumour, but may start as a small almost invisible spot. A good example of such a tumour is a malignant melanoma. This cancer usually starts as a small black spot and can either grow larger in the localised area where it occurs, or may stay small but start spreading to other organs. Once it has started spreading, it is virtually impossible to stop and invariable ends up with severe generalised cancer and death. The difficulty is that outwardly a benign adenoma growing on an animal with dark skin may look very similar to a melanoma on the same animal. It is therefore imperative that a proper diagnosis needs to be made by a properly qualified veterinarian whenever you notice any growth or discolouration which is abnormal.

Diagnostic methods for cancer in pets include the following:

The location and appearance of the cancer. Certain cancers occur very typically in certain species or on certain parts of the body. A good example is squamous cell carcinoma on the tips of the ears or nose in white cats. When a vet sees a white cat where the tips of the ears or tip of the nose has an ulcerated or raw appearance which the owner says has been coming on over a period of time, the chances are 99% that it is a squamous cell carcinoma which is a malignant locally invasive type of cancer.

Cytology – Cytology refers to the examination and studying of cells (cyto means cell). These cells are usually obtained through a fine needle aspirate, where the vet will stick a small needled attached to a syringe into the tumour or suspicious area, and squirt the content onto a glass slide, which is then examined under a microscope. Many general practitioners are competent enough to make a diagnosis there and then, however in certain cases where the diagnosis may not be simple and straight forward, your vet will send the slide off to a specialist who will then examine and come back to your vet with a diagnosis. Cells for cytology may also be obtained through scrapes, cytobrushes (a small specialised brush which picks up the cells, when rolled over it), swabs or impression smears where is slide is dabbed onto the affected area and fixed and stained with special chemicals to assist in the preservation and diagnosis.

Histopathology – Histopathology refers to the microscopic examination of tissue to look for disease (Histo is derived from the Greek word for tissue, and pathology from pathos which means suffering from disease). The vet can obtain tissue samples for histopathology in various ways but the most common is a biopsy, which is the surgical removal of some tissue (either a small part of, or alternatively the whole cancer) and sending it to a pathology laboratory where the sample is specially prepared and looked at by a specialist pathologist vet, who will then assist in making the diagnosis. A local or general anaesthetic is usually required to do a biopsy and is in most cases considered to be the definitive diagnosis for cancer. Even though a vet may have a very strong suspicion of the type of cancer (like squamous cell carcinoma’s of the tips of the ears in white cats), he or she may still send the tissue removed off for histopathology, after the cancer has been removed to confirm the diagnosis and/or to establish whether a sufficient border of healthy tissue is found around the cancer which indicates that full and proper surgical removal occurred.

Imaging technology – Imaging technology like X-rays, Ultrasound, computer assisted tomography (CAT scans), nuclear medicine, positron emission tomography (PET scans) and magnetic resonance imaging (MRS scans) are employed to assist in the diagnosis of cancer. (PET and CAT scans sound very appropriate for animals, but as the unabbreviated names indicate, have nothing to do with animals). The imaging technology does not only assist in visualising the cancer, but in many cases play a vital role in establishing the extent and invasiveness of the cancer. Most veterinary practices have X- ray or ultrasound equipment but the other modalities mentioned are very expensive, and are usually only found at referral hospitals or academic training institutions. 

No cancer or growth should ever be considered not to be serious. Rather let the vet do a thorough investigation and diagnosis, and establish a prognosis and treatment plan for your pet as soon as you notice any lump or bump or change in the behaviour of your pet.

© 2018 Vetwebsites – The Code Company Trading (Pty.) Ltd.

Pregnant women have to watch out for this bug carried by cats

Introduction

Toxoplasma gondii is a tiny organism, slightly bigger than a bacterium, called a protozoa. This parasite has a worldwide distribution, except in the absence of cats. Cats are the only animals capable of completing the life cycle of this organism. Other warm blooded animals, including cats can serve as intermediate hosts for the parasite. The organism has a very high prevalence, but rarely causes clinical disease in dogs and cats. This is an important parasite to be aware of due to the fact that it is an important zoonosis, meaning it is an animal disease that can be transmitted to humans.

Life Cycle

Cats are the only hosts capable of passing oocysts, or eggs, of the Toxoplasma parasite in their stool. These eggs are environmentally resistant and can stay in the environment for an extended period of time. They are even resistant to multiple disinfectants. Once these eggs are ingested by a cat, they penetrate the gut lining and start replicating inside cells. More eggs will form and be released into the cat’s stool. Sometimes the eggs will penetrate deeper into the gut wall and develop into a more active form called tachyzoites that replicates quickly and may cause a slight small intestinal diarrhoea. In other animals like the dog, eggs will not be excreted, and the active parasite will form tissue cysts inside cells of the body. The active parasites replicate rapidly in the cells of the liver, lungs, pancreas and nervous system. These cells are destroyed by the rapid replication and this leads to clinical disease and even death of the host animal.

When the immune response is adequate it slows down parasite replication and they go into a dormant, or resting phase by forming cysts inside tissues of the host’s body. Parasites inside the cysts divide slowly. These cysts usually form in tissue of the central nervous system or muscle. Animals either get infected by ingesting eggs shed in stool of cats or by ingesting cysts in the tissues of infected animals. Cats do not commonly eat their own stool (called coprophagia), and are usually infected through ingestion of tissue cysts of infected animals when they hunt. It has been noted that mice infected with tissue cysts become fearless of cats and therefore become easy prey. Kittens can be infected through the placenta or through the milk when they are suckling from the infected mother. The infection in kittens is often severe and they can die acutely from infection involving the liver or lungs.

Symptoms of Toxoplasma

Most cats infected with Toxoplasma will not show any signs of the disease. Cats that do show signs of disease often suffer with underlying infections of other viruses like feline leukaemia virus, feline immunodeficiency virus or feline infectious peritonitis. These infections impair their immune systems and prevents it from controlling the disease in the early stages. This is also true for immuno-compromised dogs such as those infected with canine distemper. The first clinical signs or symptoms that cats will show include depression, loss of appetite and fever. Later on as the disease progresses and depending on where the organisms are located they can become hypothermic (low body temperature), the abdomen can fill with fluid, they can become jaundiced (yellow) and may battle to breath.. Dogs and cats can become chronically infected and will show signs of eye infections (uveitis), muscle twitching, balance problems with swerving of the hindquarters (ataxia), seizures, pancreatitis and jaundice otherwise known as icterus. The neurological signs depend on where the tissue cysts form and how big they get. Muscles may also be affected together with the central nervous system and can lead to a stiff gait, weakness of voluntary movement (paresis), total loss of muscle function (paralysis), and seizures.

Diagnosis of Toxoplasma

Toxoplasma is difficult to diagnose due to infected animals often now showing any signs of the disease and because of the non-specific symptoms infected animals that do show signs have. Basic laboratory tests of the blood will give non-specific results like low red blood cell count or anaemia, increased or decreased white blood cells counts, protein in urine, increased liver and kidney enzymes. None of these results are specific to this disease. The only way a definite diagnosis can be made is by detecting the antibodies to the organism in tissue fluids like lung fluids and cerebrospinal fluid. Sometimes the eggs can be found in a cat’s stool, but this is not a very reliable way to make a diagnosis as the eggs cannot easily be distinguished from worm eggs and a cat will not always be shedding eggs at the same time he or she is showing clinical signs. Measurement of antibodies called IgG and IgM in the blood can help support the diagnoses of Toxoplasma when the patient is showing clinical signs related to Toxoplasma infection but due to the fact that healthy cats can also show high levels of both IgG and IgM, it is not a reliable method of diagnosis.

The most reliable method to make a diagnosis currently is to show high levels of IgM in cerebrospinal fluid of a patient showing related clinical signs.

Treatment of Toxoplasma

Supportive care for very ill patients is important and treatment should be started as soon as possible. The treatment of choice is an antibiotic called clindamycin but there are other combinations of antibiotics that can be used as well. Patients usually respond quickly to treatment, and failure of improvement of clinical signs within a few days usually means the diagnosis should be questioned.

Spread to humans

The most common way humans get infected is through contaminated soil. Unwashed fruit and vegetables can play a big role, as well as eating uncooked meat, especially lamb and pork. Another way of getting infected is by ingesting unpasteurised dairy products, especially goat’s milk. Mothers infected with Toxoplasma while pregnant can lead to clinical Toxoplasmosis in the foetus through transplacental infection. This can cause stillbirths, central nervous system disease and eye disease. Pregnant woman should not clean cat litter boxes or do gardening or if they have to, always wear rubber gloves. They should only eat cooked meat and wash fruit and vegetables well before use. It is also useful to keep children’s sandboxes covered to prevent cats soiling it. Due to the high prevalence of the disease it is difficult to prevent infection in cats. The only way will be to prevent cats from roaming and hunting, which is an almost impossible task! Clinical disease is also noted in immuno-compromised patients such as those with HIV and cancer. In these patients nervous system may be affected and people can die from an infection with Toxoplasma.

As with all matters related to pets, the general principles of hygiene must always be observed and regular visits to the vet for annual health check-ups and vaccinations where and when relevant, will help detect potential problems early on, so one can act pro-actively if need be.

© 2018 Vetwebsites – The Code Company Trading (Pty.) Ltd.

Frequently Asked Questions about Rabies

Aggressive Cat with RabiesHow often must I vaccinate my dog?
Puppies should be vaccinated at 3 months old with a booster vaccination required a month later and a booster given within 12 months of original vaccination. Thereafter animals who live in Rabies endemic areas like KwaZulu Natal should be given a rabies vaccination every year and animals living in non-Rabies endemic areas every 3 years by law,  but preferably also yearly, because in places like Johannesburg which is non-Rabies endemic there have been several outbreaks of Rabies in the past few years.

My child was bitten by a mouse (shrew, rat or monkey). Must he or she receive anti-rabies treatment?
If bitten by shrew or rat then contracting rabies is not likely, however, seek medical attention to treat bite wound as they can become infected. If bitten by a monkey, depending on the behaviour of the animal, anti-rabies treatment may be indicated, seek medical attention.

Must I have my cat vaccinated against rabies?
Yes. Rabies vaccination is required by law every 3 years, however preferably should be done annually.

I have been bitten by a dog. The dog is very aggressive and frequently bites people. What must I do?
Treat the wound immediately by flushing the wound for 5 – 10 minutes. Seek medical attention immediately where the doctor will determine whether vaccination and RIG therapy is required. Whereabouts and description of the aggressive dog should be reported to the authorities as a dog has bitten many people and is a risk to the population.  

I was bitten by a rabid dog four days ago and I was given rabies vaccine within a day of the incident but no RIG was administered. What must I do now?
RIG therapy is required. It can be given up to 7 days after the 1st vaccination. A person that has received RIG therapy should be observed afterwards for an hour for any harmful side effects

My farm staff dug up the carcass of a rabies-positive cow that had been buried a day ago. The staff then consumed the meat of this carcass. What must be done now?
Seek medical attention IMMEDIATELY. The farm staff will probably require vaccinations and RIG therapy. Destroy the remaining meat from the rabies positive cow by either burning or burying.

We have been drinking the milk of a rabid cow up to the day she was destroyed. What should be done?
Seek medical attention IMMEDIATELY.  Vaccination and RIG will post probably be indicated. Bury the remaining milk from the rabies positive cow.

What is the earliest age that I may vaccinate my puppy or kitten of rabies?
3 months

Is it safe to give rabies vaccine at the same time as other dog vaccines, e.g. distemper, parvo and hepatitis?
Yes

What side-effects will rabies vaccination have on my animal?
Animals may vomit,  have facial swelling, fever or lethargy. In rare instances, animals may experience anaphylactic shock, paralysis or death. However, the side effects of the rabies vaccine rarely occur and should not prevent you from getting your animals vaccinated regularly.

One of my dogs is positive for rabies. What should I do about my other animals?
It depends on your remaining dogs’ vaccination history. If your dogs have had no vaccinations then they will be humanely destroyed. If they have had rabies vaccinations by a registered veterinarian or authorised official and you have proof of these vaccinations, then the dogs will receive a rabies vaccination booster on day 0 and day 3, the dogs will be placed in quarantine for 6 months, and if there is no change in behaviour, then the dogs can be released from quarantine.

How soon after vaccination are my dogs protected against rabies?
7 – 10 days

Should wild animals which are kept as pets be vaccinated against rabies?
Wild animals should be vaccinated against rabies however the immune response would be unknown as current rabies vaccine is tested for domestic animals.

My cow was positive for rabies. What must I do about this cow’s calf and the other cattle that were in contact with this cow?
Contact your state veterinarian. He/she will decide if humane slaughter or isolation and vaccination is necessary.

My dog and cat were vaccinated during a rabies campaign. However, I do not have any documentary proof that vaccination was done. Should there be contact with rabid animals, what is their vaccination status?
Your dogs’ and cats’ vaccination history is considered unknown and would, therefore, be considered not up to date. Blood can be taken and a rabies titre determined. If greater then 0.5iu/ml then this indicates that the animal has adequate protection against rabies, and should be kept isolated from other animals for 6 months, if there is no change in behaviour then the animal can be released.  If the titre is less then 0.5iu/ml, contact your State Veterinarian to find out the next step as there was the only contact between your pets and a rabid animal and no report of a bite. The next step could be quarantine or humane destruction.  Getting and keeping a formal record of Rabies vaccination is critically important and as it is governed by law it is like driving without a driver’s licence.

Can rabies be transmitted between people?
Yes but only if a rabid human bites another person or receives an organ/blood transfusion from a rabid human.

I was bitten by a mongoose two weeks ago. What should I do?
Seek medical attention immediately even 2 weeks after the bite. Wound treatment, vaccination and RIG therapy can be started.

Can birds contract rabies?
No

What part do bats play in rabies transmission in South Africa?
The risk of rabies transmission is highest in bats that feed on blood. Vampire bats are not found in South Africa. It is unlikely that a bat that usually feeds on fruit, insects or pollen would contract rabies. However, bats are mammals and can, therefore, contract Rabies and an accidental scratch or bite from infected bats could potentially cause rabies in a person.  Rabid animals lose their fear of humans and as unsolicited aggression is a known symptom of Rabies, it should always be considered a possibility if a human is bitten by a bat.

Can clinical rabies in humans be treated?
The treatment for clinical rabies involves sedation, pain management, and the maintenance of fluid and electrolyte balance. There is no cure for clinical rabies in humans and in most cases the disease is fatal. Family members should be informed of the poor prognosis and receive the necessary counselling and support that they need.

© 2018 Vetwebsites – The Code Company Trading (Pty.) Ltd.

Rabies

Rabies, a fatal disease of humans and all other mammals, is caused by a virus which has been associated with animal bites for more than 3 000 years and it is the oldest infectious disease known to medical science. Dogs have long been recognised as the main transmitters of the disease to people. When compared with other formidable human diseases such as Bubonic Plague and Smallpox, and animal diseases such as Rinderpest and Anthrax, Rabies has probably never caused comparably high numbers of deaths in humans and animals. However, the horrendous manner in which Rabies manifests itself in its victims continues to attract the attention of scientists, health and veterinary workers. The true scale of Rabies in South Africa remains clouded by the many thousands of people protected by post-exposure treatment each year after Rabies exposure and the undiagnosed human and animal Rabies cases not reflected in official statistics.

Animal Rabies is endemic throughout South Africa and the disease is currently responsible for the laboratory confirmed deaths of between 10 and 30 people each year. Tragically, with very few exceptions, those who succumbed to the disease over the past decade did not receive the correct post-exposure prophylaxis and died following bites by rabid dogs.

There have been several new and exciting developments in our knowledge of the disease and in measures used to control Rabies in South African animals. The use of monoclonal antibody typing, together with gene sequencing technology, have revealed several different strains of the Rabies virus, some of which appear to show clear host preferences. The entire country was declared Rabies-endemic during 1999 and it is now compulsory for all dogs and cats to be vaccinated at least once every three years.

Shedding of virus in saliva usually occurs simultaneously with, or soon after, the appearance of clinical signs and progressive with death usually within 10 days in animals and five days or less of the onset of Rabies symptoms in humans (J.D Godlonton, personal communication).

Following central nervous system infection, the virus is transported centrifugally along cranial nerves and along motor and sensory pathways as well as the spinal cord. This results in the presence of viral particles in peripheral nerve tracts in many tissues, particularly those of the head. Therefore, a diagnosis of Rabies may sometimes be possible by examination of skin sections, where antigen can be detected within nerve tracts, or corneal smears.

In all mammalian species the host is not infectious for most of the incubation period. Rabies infection is fatal in all species and no species is known to have a carrier state where virus is shed in the absence of clinical signs or imminent clinical signs. Exceptional and rare cases of human survivors have been recorded in a handful of cases where the patients did receive some prophylaxis but had severe residual neurological sequelae. To date only one case of a human survivor has been recorded in a patient who did not have any history of prophylaxis. The reason for the patient’s recovery is still being investigated and disputed.

Animal and human Rabies vaccines consist of inactivated whole-virus antigens on a cell culture or neural tissue substrate and, in the case of more modern cell-culture vaccines, partially purified to remove unnecessary proteins. Generally, veterinary pre-exposure vaccination, while human vaccines, which are considerably more expensive to produce, are used post-exposure. Pre-exposure vaccination may be recommended in people at high risk. There are no records of human Rabies cases that have occurred in people fully vaccinated according to World Health Organisation (WHO) recommendations.

Post-exposure prophylaxis of humans, using vaccine and immunoglobulin according to WHO recommendations, provides rapid and effective protection if administered soon after exposure. The most frequent causes of failure of post-exposure prophylaxis are delays in administering the first failure vaccine dose or immunoglobulin, failure to complete the vaccine course and failure correct wound management. Infiltration of the wound with immunoglobulin does not interfere with stimulation of the immune system by vaccine, which is administered at a site distant from the wound.

Rabies appears to spread fairly well within bat-eared fox populations, yet transmission of infections to other species is relatively rare. The underlying reasons for this are still to be elucidated. Population dynamics (including population turnover) and the distribution of susceptible animals are extremely important factors determining the prevalence of Rabies in other species, and the bat-eard fox is no exception.

The most important maintenance host of mongoose Rabies is the yellow mongoose, Cynictis penicillata, a diurnal animal that lives in colonies of 10 or more individuals. The disease has been endemic in yellow mongoose populations for decades and possibly centuries. Attempts by veterinary authorities to control the disease by depopulation, for example by gassing burrows and trapping, have only had a transient effect. These measures may ultimately have accelerated the spread of the disease by increasing the territories of yellow mongoose colonies with concomitant increase movement. Spreading infection to suricates, which are migratory herpestids living in groups of up to 30 individuals, and ground-squirrel populations are fairly common, because these species often share warrens or live in close proximity to yellow mongoose colonies.

Humans and domestic animals such as sheep, cattle and dogs have been infected and succumbed to mongoose Rabies virus but are regarded as dead-end hosts because spread within these species is rare.

Clinical signs

Apart from behavioural changes, there are no definitive, species specific clinical signs of Rabies. Although certain clinical signs are more frequent than others, even the most experienced diagnostician may make an incorrect diagnosis when presented with an unusual case. Rabies can mimic many other diseases but it always has a neurological component.

Because Rabies affects the central nervous system, it is nearly always associated with behavioural changes that may manifest in many different ways. Classically, Rabies has been described as having a prodromal phase followed by either an excitive furious form, or a paralytic dumb form.

The veterinarian is, however, rarely afforded the opportunity to observe an animal throughout the clinical course of disease and diagnosis is often made after minimal observation, especially in endemic areas where Rabies awareness is heightened.

Dogs:

Change in temperament, attacking and biting anything (often injuring mouth and breaking teeth), exaggerated responses to sound and light, restlessness, nervousness, snapping at imaginary flying insects, disorientation, wandering aimlessly, a fixed stare, drooling saliva, hoarse howling, choking sounds, “bone in throat” syndrome, a febrile reaction, uncoordinated actions and progressive paralysis, dilated pupils, irritability, photophobia, infliction of self-injury, convulsions, and muscle spasms.

Cats:

Generally aggressive, uncoordinated , frothing, muscular tremors, dilated pupils, staring, a threatening posture, abnormal vocalisation, lack of response to owners, unprovoked attacks, biting (sometimes without releasing grip), convulsions, paralysis, coma, hiding away, some cats appear unusually affectionate and purr, or extend and retract their claws.

Cattle:

Several animals may have clinical signs at the same time, a typical hoarse bellow, aggressive particularly on provocation, vicious attacks on inanimate objects, butting other cattle, attacking humans, wind-sucking, “bone in throat” syndrome, separate themselves from rest of herd, anorexia, knuckling of fetlocks especially hind limbs, swaying gait, tail and posterior limb paralysis, jaw and tongue paralysis, profuse salivation, dragging hooves, pseudo-oestrous, hypersexual behaviour, decreased milk production, dilated pupils, fixed stare, grinding teeth, pica, tenesmus with diarrhoea, frequent urination, loss of condition, and emphysema.

Sheep / goats:

Symptoms resemble those of cattle but hypersexual behaviour, sexual excitement, incessant bleating, aggression, aimless running, pawing and paddling, and grinding of teeth are prominent.

Horses:

Febrile reactions, altered behaviour, biting of wound site, aggression, thrashing, paralysis, and inability to swallow.

Pigs:

Hiding in corners of pen, hypersexual behaviour, aggression, biting, and may kill off springs.

Wild animals:

Often lose fear of humans.

Yellow mongooses generally demonstrate tame behaviour, but some are very aggressive.

Jackal are usually aggressive, and lose fear of humans.

Wild cats display similar behaviour or domestic cats. Badgets are usually victim and fierce.

Kudu salivate profusely, may be paralysed, docile, tame, even entering houses. Duiker are sometimes very aggressive.

Diagnosis

Confirmation of a clinical diagnosis of Rabies cannot be made by gross pathology or histology. Specific test must demonstrate the presence of Rabies antigen. Animals displaying signs of neurological disease, and all stray and wild animals suspected of exposing humans to Rabies infection, should be euthanized for examination. The Directorate Veterinary Services may hold suspected cats and dogs in quarantine for observation by a veterinarian for a period of at least 10 days. Animals displaying signs of illness during the period of observation are euthanased for laboratory examination. A vaccination history may be of some assistance during the assessment but greater reliance should be placed on the animal’s clinical picture. Although the inactivated veterinary vaccines used in South Africa are known to be extremely effective for periods exceeding three years following vaccination, there are compelling reasons for avoiding undue reliance on vaccination history alone.

These include:

  • The incorrect vaccine may have been administered
  • The incorrect dosage and route may have been used
  • The vaccine may have been incorrectly handled or stored
  • The animal may have been misidentified
  • Vaccination may have been performed after infection had already occurred
  • The animal may have been immuno-suppressed
  • The animal may have been diseased or in poor condition when vaccinated
  • The animal may have been diseased or in poor condition when vaccinated
  • The animal may have been very young at vaccination and nod boosted at three months.

Prevention of Rabies

Pre-exposure vaccination

A number of recently developed, highly effective, thermo stable, inactivated vaccines are available in South Africa for veterinary use. The duration of immunity conferred varies from one to three years. Most veterinary vaccines are only registered for use in specific species, for example dogs. Although there are no safety limitations to their use, their efficiency in other species, for example mongoose, is not guaranteed. All Rabies vaccines registered for human and animal use must conform to established potency standards. A minimum antigenic potency of 2,5 IU per dose is mandatory.

The vaccines may be used in young pups, but they must be boosted at three months of age and again within the following year. Revaccination must be carried out every three years thereafter. Cattle and sheep may be vaccinated annually or every two to three years, depending on the vaccine manufacturer’s instructions. Some farmers inoculate their herds every year in jackal and dog Rabies endemic areas with these inexpensive vaccines as they consider this practice to be economically sound.

Following an outbreak in domestic livestock, vaccination of animals without visible bite wounds is strongly recommended. In cases where bite wounds are visible, or there is direct evidence that an animal was bitten, the animal should immediately be isolated and destroyed.

Post-exposure prophylaxis

Post-exposure prophylaxis (PEP) of bite-contact unvaccinated carnivores, including dogs and cats, is not recommended in South Africa. Preliminary reports indicate that antibodies in the form of anti-Rabies immunoglobulin (RIG) in combination with vaccine yielded poor results. The use of PEP in animals is not without risk and is not recommended for use in animals in South Africa.

Rabies in Humans

Epidemiology of human Rabies

Rabies is an ongoing scourge exacting an unnecessarily large toll on human life. The World Health Organization estimates about 55 000 human deaths in canine Rabies endemic areas (31 000 in Asian countries and 24 000 in African countries) annually. Rabies virus is transmitted via the saliva of infected animals and has the highest case fatality rate of any known human infection if the disease has manifested. Once the virus has entered the central nervous system of the host, the resulting encephalomyelitis is fatal. Fortunately the availability has prevented many fatalities and almost 10 million people receive post-exposure prophylaxis annually after potential Rabies exposure, mostly following dog bites.

Distribution in South Africa

During the first half of the 20th century most human Rabies cases in South Africa resulted from herpestid, particularly yellow mongoose, bites in the central plateau areas. However, following the introduction of canid virus into Limpopo Province in the late 1940s, and later into KwaZulu-Natal in 1961, dogs became the most important source of human infection. In recent years the last majority of South African human Rabies cases have followed bites from infected dogs in KwaZulu-Natal. An outbreak of Rabies in dogs coincided with a dramatic increase in the number of human cases in the Limpopo Province in 2006.

Most victims have been children under the age of 10 years. Children are particularly vulnerable because of their height, inquisitive nature, interest in animals and inability to protect themselves. Surveillance of human Rabies is poor in many parts of South Africa and it is likely that the situation may be worse than that reflected by official notifications. A careful history taken from a victim’s family has demonstrated a high sensitivity for diagnosing Rabies in other African settings and may prove a useful approach in areas suspected of having Rabies cases that have not been notified.

Canine vaccine delivery targeted to highest risk populations and broad intersectoral collaboration are believed to have contributed to the marked reduction in human Rabies in KwaZulu-Natal during the latter part of the 1990s.

Transmission to humans

Human Rabies cases result from viral introduction through broken skin or mucosa through encounters with rabid animals, particularly bites, but also scratches and nicks. Virus is usually present in the saliva of the affected animal during clinical disease but secretion may be intermittent. Experimental demonstration of virus in salivary glands or saliva several days before risk of transmission during slaughtering, these cases are usually classified as category 2 exposures and require the administration of vaccine, or when physical injuries have been acquired during slaughtering as category 3 exposures.

As all mammals are susceptible to Rabies, any infected mammal could potentially transmit Rabies to humans. However mice, rats, shrews and monkeys have yet to be incriminated as vectors of Rabies in South Africa. Rats and mice, particularly those kept as pets, frequently inflict retaliatory bites on children when cornered and caught. Rabies infection has never been shown to transmit Rabies virus in South Africa, they are however vectors of Rabies related viruses such as Duvenhage virus and Lagos bat virus.

Preventing human Rabies

Rabies is one of the top 10 global infectious causes of mortality and one of the most amenable to available preventative measures. Primary care providers can play a crucial role in preventing Rabies, by providing accurate prevention messages including the avoidance of suspicious animals, immunising people at high risk of Rabies exposure, ensuring optimal wound management, and correctly administering immunoglobulin and Rabies vaccine after suspected exposure to Rabies virus.

Pre-exposure prophylaxis

A recent review found that at current Rabies vaccine prices, routine use of pre-exposure vaccinations is generally not cost-effective. There are, however, particular high-risk situations where pre-exposure vaccination is cost-effective and it would ne negligent not to recommend it. In South Africa the cost of pre-exposure prophylaxis is borne by vaccine recipients or their employers.

Pre-exposure vaccinations involves administration of Rabies vaccine on days 0, 7 and 28 (or day 21). Variation of a few days in the timing of second and third doses does not, however, affect the immune response. Currently, two vaccines are licensed for use in South Africa, the purified chick embryo cell culture vaccine and the purified vero-cell culture vaccine. These vaccines are considered safe and effective when administered according to the guidelines put forward by the World Health Organization.

Practically all human Rabies cases result from introduction of virus through broken skin by the bite of a Rabies infected mammal

Rabies vaccine induces an active immune response that includes the production of neutralising antibodies. The antibody response requires approximately seven to 10 days develop. The duration of persistence of this booster vaccinations. Routine serological measurements of the vaccine recipient’s blood can indicate the presence of levels considered adequate for protection. Virus neutralizing antibody levels of greater than 0.5 IU/ml are considered to be protective by the World Health Organization. A small study confirmed rapid boosting of antibodies up to 19 years after a previous vaccine course.

As it has repeatedly been found that people with intact immune systems experience a satisfactory response to approved vaccines, it is only necessary to demonstrate an adequate serological response in immunocompromised individuals or those working with live virus and those who are blood donors for Rabies vaccines products. Rabies-neutralising antibodies are analysed by a neutralisation test. Two booster vaccinations (day 0 and day 3) should be administered to all vaccinated individuals that has had risk of exposure to rabid animals irrespective of their antibody titres and they should not receive immunoglobulin.

Although a two-dose schedule (days 0 and 28) has also been investigated, results have confirmed the superior long-term immunogenicity of the three-dose approach for pre-exposure prophylaxis.

High-risk occupational groups

People with increased occupational risk of exposure to infection, such as veterinary staff, wildlife handlers, laboratory personnel working with Rabies virus or animal welfare staff, should receive pre-exposure prophylaxis. This should preferably be by administration of three doses vaccine into the deltoid muscle on days 0, 7 and 28 (or day 21).

Because the virus may be present in the saliva of patients with Rabies, there is a potential risk of health worker exposure.

Human to human transmission has however never been reported under these circumstances. Infection control measures to protect health workers caring for patients with Rabies should be instituted to protect against bites and exposure to infected saliva: gowns, gloves and goggles. Post-exposure prophylaxis with Rabies vaccine may be considered in selected cases if there has been significant exposure i.e. bite from an infected patient. Surveillance staff responsible for bleeding dogs as a plague indicator species in Rabies endemic areas are another occupational group that clearly merit pre-exposure vaccination.

Children in Rabies-endemic areas

Routine vaccination could be beneficial for children in countries where Rabies is enzootic. As children are particularly vulnerable and experience a higher frequency of bites to the head and neck as a result of their inclination of Rabies vaccine in the Childhood Expanded Programme on Immunisation in Rabies Vero cell vaccine with diphtheria, tetanus, whole-cell pertussis and inactivated poliomyelitis vaccine and administering these vaccines at two, three and four months, or alternatively at two and four months, resulted in all infants developing protective antibody concentrations against all five diseases with no serious adverse events. A larger trial, also in Vietnamese infants, comparing intramuscular and intradermal vaccine administration demonstrated that both routes provided acceptable antibody titres (0.5 IU/ml).

Unfortunately current vaccine costs prohibit routine childhood vaccination against Rabies. There is, however, a clear mandate for children to be formally educated on Rabies transmission, the disease and prevention, particularly as educational interventions have proven effective in reducing the number of dog bites in children.

Rabies and travellers

Rabies in an important disease for the burgeoning travelling community. In the United States, for example, 37% of people dying from Rabies are infected in foreign countries. Canine Rabies is endemic in some of the developing countries of Asia, Africa and South America. This poses a risk to travellers, particularly in the backpacking or adventure category. Unfortunately discussion on reducing Rabies risk is one of the topics often neglected by travel medicine advisors during pre-travel consultations. Travelling to these areas must be educated concerning their risk of Rabies exposure and informed regarding local reservoir species so that they can avoid contact with potentially rabid animals. They should also receive instruction on correct wound cleaning, the importance of correct post-exposure prophylaxis with vaccine and immunoglobulin, and their availability at the traveller’s destination.

Travellers with potential occupational exposure should certainly receive appropriate three-dose pre-exposure vaccination and this should also be considered for all long-term expatriate residents in high-risk areas, particularly those living in close proximity to the local population and their dogs.

Debate continues over the merit of administering routine pre-exposure vaccination for other categories of international travellers to Rabies-endemic countries. The rate of animal bite exposure in international travellers has been estimated to be two to four people per thousand and in the majority of these cases there is some concern about Rabies infection. However, where correct post-exposure prophylaxis is available, this is effective in preventing Rabies and pre-exposure vaccination is of less importance. Although local reactions, such as pain, swelling and itching, occur in most vaccine recipients and mild systemic reactions, such as headaches, nausea, muscle aches, abdominal pain and dizziness are reported by 5 to 40% of people vaccinated, serious adverse events are rare. The major constraint against routine administration remains the cost of pre-exposure vaccination. The cost, for example, of preventing Rabies in United States tourists to Thailand by routine pre-exposure vaccination was estimated at between US$ to 50 million per Rabies death prevented.

The death of a human from Rabies should be viewed as a health failure

On the other hand, areas where stray dogs are a problem are often the specific areas where canine Rabies is endemic, and efficacious vaccines and immunoglobulin are not available.

Fraudulent vaccines, nerve-tissue derived vaccines and equine immunoglobulin commonly associated with severe adverse reactions may be used in these countries. In certain areas tourists are frequently exposed to dogs, for example a survey of European travellers in Thailand found that in less than a three week period 1.3% of tourists experienced dog bites and 8,9% dog licks. Advantages of pre-exposure Rabies vaccination include requiring only two boosters, on day 0 and 3, if there is an exposure, no need for immunoglobulin, and diminished concern about inadequate therapy and vaccine failure.

Advice and vaccination should be adapted to the individual needs and exposure risks of traveller, taking into account the area visited, local Rabies epidemiology, mode of travel, and underlying medical conditions and medication. Travellers who are immunocompromised by disease or selected medications are a group deserving particular attention as immune response to vaccine for which Rabies pre-exposed vaccination is indicted. When this is not possible, immunocompromised individuals who are their antibody titres checked post-vaccination.

Management of humans exposed to Rabies

The death of a person from Rabies should be viewed as a health system failure. This contention is supported by e review of failure post-exposure prophylaxis in Thailand, which found that delays, failure to provide post-exposure prophylaxis or deviations from the recommended regimen contributed directly to the deaths of young children.

Findings from studies in South Africa and Thailand have highlighted deficiencies in health workers’ knowledge on managing suspected Rabies exposures.

It is therefore recommended that a confidential enquiry routinely be conducted to establish avoidable factors which may have contributed to the death.

Although no controlled human trial of Rabies post-exposure prophylaxis utilising wound treatment, immunoglobulin and vaccination has been conducted and such a study would be unethical, extensive global experience provides convincing support for this approach.

There is a critical need for veterinary and health workers to be adequately trained on assessing Rabies risk and appropriate response. It is also imperative that health and veterinary workers involved in managing human cases with potential exposure to Rabies virus remain in close communication so that patient management can be modified by data about the source animal. The health worker is obligated to make contact with the responsible state veterinarian. Laboratory-confirmed human Rabies and exposure to proven rabid animals is notifiable in South Africa.

Assessing risk after exposure

Important factors that assist decisions on prophylaxis, include details of the nature of the contact and the implicated animal’s behaviour. It is imperative that prophylaxis be instituted as soon as possible after exposure to Rabies in the animal. Ideally post-exposure prophylaxis should be administered to all bite victims, but availability and costs of the biological is a problem. The approach adopted in South Africa on providing prophylaxis to those individuals at high risk of Rabies infection.

To reduce the risk of Rabies, it is important that thorough cleaning of the bite wound is initiated as soon as possible

Judgement on whether to initiate post-exposure prophylaxis is assisted by an estimation of risk based on the following criteria, with a high risk of exposure necessitating vaccination:

  • Type of contact. Bats may be involved in transmitting Rabies-related viruses, i.e. Duvenhage and Lagos Bat virus, and any encounters should be considered. Small rodents e.g. Mice rats commonly found in an around dwellings are not typically associated with Rabies. To date in South Africa there has only been one transmission of Rabies associated with a bite from a baboon.
  • Incidence of Rabies in the animal’s district of origin
  • Animal’s behaviour (any abnormal behaviour could indicate Rabies)
  • Species of animal involved
  • Vaccination status of animal (if not vaccinated, then higher risk)*
  • Results of Rabies laboratory testing (a negative result from an approved Rabies veterinary laboratory indicates a lower risk)
  • When the biting animal cannot be traced, caught or identified, or the brain is not available for laboratory examination, it should be assumed that the animal was rabid.
  • An animal vaccinated before 3 months of age with no booster may not be protected from Rabies.

There is no blood test for the human victim that can confirm or exclude transmission of Rabies virus from an infected animal.

Any decision to provide post-exposure prophylaxis is made on the risks of the exposure to the human victim. Post-exposure prophylaxis should not be delayed pending the results of Rabies laboratory tests in the animal.

The most important criteria are the non-availability for assessment of the biting animal in an endemic area, abnormal behaviour in the animal and type of contact. If in doubt, it is preferable to vaccine.

In the case of AIDS patients (or otherwise immunosuppressed patients) it is particularly important to focus on thorough wound care when a Rabies virus exposure is suspected. The immune response to Rabies vaccine has been shown to be decreased in HIV infected persons. It is therefore advised that human Rabies immunoglobulin be administered together with vaccine not only for category 3, but also for all category 2 exposures for these patients. No other administration is currently advised.

Management of the wound

To reduce the risk of Rabies, it is important that thorough cleaning of the bite wound in initiated as soon as possible. The bite wound should ne copiously flushed immediately for 5 to 10 minutes with water or soap and water, while irrigation of deep puncture wound, for example following a feline bite, should be performed using a syringe. If antiseptic is available, for example a 1 in 20 dilution of 5% chlorhexidine in water, then this may be added to the water. Bleeding should be encouraged and wound suturing should preferably be avoided or delayed. Applying an iodine-based disinfectant or 70% alcohol to the wound after flushing is also indicated, as these chemicals inactivate Rabies virus.

To lessen the risk of bacterial infection, antibiotic therapy should be considered. As most infections following mammalian bites comprise multiple pathogens, with mixed aerobic and aerobic species, it is essential that therapy should be selected appropriately. In addition to the usual aerobic and anaerobic Pasteurella multocida, which is isolated in 20 to 30% of dog-bite wounds, and is particularly associated with cat bites, and a cause serious infection with severe complications, and Capnocytophaga canimorsus, which can induce sepsis following apparently minor bites particularly in immunocompromised individuals particularly those without a functioning spleen.

Antibiotic therapy is modified in line with laboratory culture susceptibility results when a patient requires hospitalisation as a result of severe local or systemic sepsis. Additional indications for hospitalisations include penetrating injuries of tendons, joints or the central nervous system, severe bites to hands or head and neck, patients requiring reconstructive plastic surgery with certain high-risk medical conditions, for example diabetes, asplenia, and peripheral vascular disease.

The administration of anti Rabies immunoglobulin complements Rabies vaccination in situations where viral transmission may have occurred

To prevent tetanus, a booster dose of tetanus toxoid (TT) absorbed vaccine (0.5 ml intramuscular) should be given at the time of wound treatment in individuals who have completed a primary course of tetanus vaccination. Most adult tetanus cases occur in people who do not have a vaccination history. However, the benefits of regular tetanus boosting throughout adult life are sufficient to justify the costs of an administration programme and potential sensitivity reactions.

Human anti Rrabies immunoglobulin

The administration of anti Rabies immunoglobulin (RIG) complements Rabies vaccination in situations where viral transmission may have occurred, as production of vaccine-induced neutralising antibodies take seven to 10 days after vaccination. RIG is safe and provides rapid passive immunity that persists with a half-life of approximately three weeks.

The human RIG currently used in South Africa is produced by fractionation of pooled serum from immunised persons. The introduction of human RIG proved a valuable replacement to the previously used anti-Rabies serum prepared in horses. Although the latter was effective and is still used in many developing countries, it may induce serum sickness. To ensure between 2 and 8°C during handling and storage. All patients who have received RIG should be observed for an hour thereafter. An emergency pack for treating anaphylaxis should be available.

The dosage of human RIG currently available in South Africa is 20 International Units (IO) per kg body-mass. RIG is supplied in 2 ml ampoules with a virus-neutralising antibody content of 300IU. Preferably the complete dose of RIG should be infiltrated into the depth of the wound or tissue immediately adjacent to the wound. Where this is not anatomically possible, the remaining RIG may be injected intramuscularly into the deltoid muscle. RIG was traditionally administered into the buttocks, but there is evidence of low circulating Rabies neutralising anti-Rabies following RIG injection into gluteal fat. With multiple wounds, where the dose of RIG based on body mass is insufficient to infiltrate all wounds, the dose must be diluted up to 50% in saline to allow infiltration of all wounds. Failure to infiltrate all wounds is believed to have contributed to the deaths of a number of children. Local anaesthetic agents should not be used to facilitate RIG administration.

RIG is administered on the day of initial patient presentation, traditionally referred to as a day 0, with the first dose of vaccine but at separate injection sites. This is irrespective of the time elapsed since exposure, which represents a departure from the previous recommendation that RIG should only be given to patients presenting within a week of exposure. If RIG is not available when vaccination is initiated, it may be administered up to day 7 after the administration of the first vaccine. RIG administration is not recommended prior to vaccination, nor is it currently recommended for individuals who have received pre-exposure vaccination as it is believed that RIG may interfere with the rapid anamnestic response to vaccine.

Rabies vaccines

Rabies vaccine, when given post-exposure, induces immunity within seven to 10 days. Two cell-culture vaccines are currently registered for use in South Africa, i.e. purified chick embryo cell culture vaccine (PCECV) and purified Vero-cell Rabies vaccine (PRVR), and are highly purified and inactivated vaccines that meet the WHO potency standard of greater or equal to 2,5 IU per dose.

All persons judged to be at high risk for Rabies exposure should be vaccinated, with treatment being initiated as soon as possible even if there has been a delay in presentation to the health service. The treatment/prophylaxis schedules presented here are based on the most recent WHO recommendations, and are valid for the cell-culture vaccines registered in South Africa. However, it must be emphasized that the Essen intramuscular regimen is the only recommended schedule and administration route for South Africa, and expert advice should be sought before using an alternative regimen. The vaccination schedule may be discontinued if the suspected source animal remains healthy for 10 days after the exposure or if an approved veterinary laboraoty reports the brain specimen from the animal as negative.

Rabies Legislation

Human Rabies and the law

There are a number of important legal considerations relating to the diagnosis, management reporting of Rabies in humans in South Africa.

Negligence

When deciding whether a doctor has been negligent the court issues whether the doctor concerned acted as a “reasonable medical practitioner would have done under the same circumstances”. Four questions are usually considered; if the first two are satisfied then the accused person is said to have owed the injured person a “duty of care”. Whether this has been breached is determined by answering the next questions.

The questions are:

  • Would a reasonable medical practitioner in the same position have foreseen harm?
  • Would a reasonable medical practitioner have taken steps to guard against occurrence of harm?
  • What steps would a reasonable medical practitioner have taken to prevent the harm?
  • Did the accused take these steps?

The more serious the potential results, and the greater the likelihood that harm will occur, the greater the possibility that the courts will impose a duty of care.

Therefore, with the existence of national guideline on the management of persons potentially exposed to Rabies in South Africa, breach of these guidelines, for example failure to adequately treat the wound, failure to notify a state veterinarian or police officer about the existence of a potentially rabid animal, failure to complete the correct regimen of post-exposure prophylaxis, would most likely be considered unreasonable care and therefore negligence.

The Health Act (Act No. 63 of 1977)

In terms of section 45 of the Health Act (Act No. 63 of 1977) Rabies is a notifiable disease. It is therefore required that the responsible local or provincial authority and state veterinarian be informed of any human tabbies case, death or contact on the prescribed form, GW17/5/ Rabies is unique as it is the ONLY notifiable disease where contact by a person with an infected animal is also notifiable.

Post mortem

A suspected Rabies should be considered as due to an unnatural cause. A definitive diagnosis is of particular importance where an animal owner may be liable for not ensuring that his/her dog or cat was vaccinated according to legal requirements. A post-mortem should be requested and although relatives should be counselled, consent to conduct the post-mortem is not necessary.

Animal Rabies and the law

The Animal Diseases Act (Act No. 35 of 1984) provides for the control of specific animal diseases and for measures to promote animal health. The Minister of Agriculture may make regulations for accomplishing the purposes of the Act and has determined that Rabies control measures should be applied throughout the country. The decision was based on the geographical distribution of animal Rabies cases diagnosed over a five year period from 1995 to 1999.

The Animal Disease Regulations identify Rabies as a controlled animal disease.

The information in this article comes from The Guide for the Medical, Veterinary and Allied Professions compiled by the Department of Agriculture, Forestry and Fisheries, Republic of South Africa.

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A killer disease with a misleading name

The name of a particular disease is often influenced by the circumstances around the original occurrence of such a disease. For example “sleeping disease” in humans was originally associated with the green fever trees found in low lying areas around South Africa. As time went by and a better understanding of the disease became apparent, it became clear that the disease was transmitted by Tsetse flies and had nothing to do with the trees. Similarly there is a killer disease in dogs with a misleading name – CATFLU. When the disease was first diagnosed in the late 1970’s, it was thought to be a disease transmitted from cats to dogs. Later it was discovered that cats did not harbour the offending organism causing the disease, but an extremely small yet resilient virus called, Parvo virus in actual fact is responsible for the disease.

The good news is that Catflu in dogs can be prevented with vaccinations and therefor vets recommend that all puppies start on a vaccination program from 6 weeks of age. If the puppies managed to take in the first milk (also known as colostrum) from the mother, in the hours after they were born, and the mother had been previously vaccinated or contracted the disease and survived, then antibodies or “soldier cells” will be transferred from the mother to the pups via the mother’s milk, which will offer the puppy some initial protection. This protection wanes over time and usually the levels are too low between the ages of 4 and 8 weeks to offer protection on its own, should the puppy be exposed to the Parvo virus. The first vaccination is therefore usually given around 6 weeks of age. This vaccination needs to be repeated monthly (also called booster vaccinations) for two to three months, to make sure that the puppys’ antibodies or “soldier cells”, which it got after birth from the mother’s milk, does not kill the vaccine and render it ineffective.

Parvo virus is a really small virus compared to other viruses but it has a strong capsule around it, which protects it from the environment and which makes it incredibly tough to destroy. It can survive in the environment for up to six months to a year in a moist humid environment. The main source of infection comes from the stool of infected dogs. The virus is quite resistant to many cleaning agents but fortunately there are some commonly used household cleaning agents like bleach as well as swimming pool chlorine which work well to destroy it. If one suspects at any time that there may be some parvo viruses in an environment in which dogs are kept, it will be a good idea to disinfect the area with swimming pool chlorine.

The parvo virus loves to attack the fast dividing cells in the body, and therefore symptoms of the disease are associated with the systems which are affected by the destruction of cells in these systems. The cells most commonly targeted are the intestinal lining cells (which in the normal course of events gets replaced by new cells every twenty four to forty eight hours), the lymphnode cells (which are like remote army bases around the body and assist in fighting local infection) and the bone marrow cells (which produce red and white blood cells and assist the body in fighting general infection and provides the body with its best defence system). The symptoms seen because of the virus attaching the intestinal lining cells are usually vomiting and diarrhoea (often bloody), which goes hand in hand with a loss of appetite and a rapid deterioration of the dog’s general habitus or status of well being leading to lethargy (sluggishness) and weakness. Damage to the intestineal lining prevents nutrients from being absorbed properly. Because the defence mechanisms of the body are being affected by the virus attacking the other fast dividing cells in the body as well, the disease usually progresses fast and dogs contracting catflu can die of dehydration and severe infection within 24 to 48 hours. As with many other types of infections, a fever can often be present with catflu. The incubation period (the period from when the dog is first exposed to the virus and contracts it, to the time it starts showing symptoms) is usually between three to seven days.

The challenge with treating dogs which have contracted catflu are that unlike bacterial infections, where antibiotics are very effective in killing bacteria, there are no systemic antiviral remedies which are effective enough to actively kill the virus. Therefore the killing of the virus (“enemy”) has to be done by the body’s own defence mechanisms – antibodies (“soldier cells”), which are produced in reaction to the virus attacking the body. This may take a few days and the only way to assist the body in this process is by giving supportive treatment like intravenous fluids replacing essential electrolyte losses, administering medication via injections which supports symptomatic treatment of the nausea (preventing vomiting and loss of body fluids), diarrhoea (preventing dehydration and loss of fluids via an overactive intestinal tract), and treatment with antibiotics to prevent secondary bacterial infection.

Once treatment has started it can take anywhere between 1 and 10 days, to establish whether the animal will survive, often with a bitter life and death battle. If an animal presents to the vet in a dehydrated state to start off with, the chances are likely that the animal may not survive, even with aggressive supportive treatment. Treating the dehydration is only one part of fighting the disease. Because the virus attacks the bone marrow and destroys immune system cells, there is usually a decrease in white blood cells which means the body is almost defenceless. Add to that the destruction of the intestinal barrier (the cell lining of the intestines), which allows bacteria, which normally live in the gut, to freely access the bloodstream, leading to septicaemia and overwhelming infection,  and you have a recipe for disaster.

Some breeds of dogs seem to be more adversely affected than others and for some reason black and tan breeds like Rottweilers, Dobermans, German Shepherds and Miniature Pinchers are more likely to die than other breeds as a result of contracting catflu. Having said that, other breeds are by no means safe when contracting catflu, and the quicker you can get your dog to the vet once it shows any sign of disease, the better.

The most important means of fighting the disease is prevention by vaccination. Effective vaccines which cover a wide range of virus strains have been developed and having your puppy and older dogs vaccinated at the correct times and intervals, can prevent this disease.

Even though cats and dogs have been traditionally pitched against each other as arch rivals, catflu is one instance where the cats are innocent, and have been blamed for a killer disease they are not responsible for.

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