Common dog illnesses and how to know your dog is not well

Common dog illnesses and how to know your dog is not well

While some dogs live exceptionally healthy lives, the majority of our furry friends will experience an illness, allergic reaction, or some kind of system imbalance that requires veterinary treatment. Dogs are well-known stoics – they don’t want us to know they’re sick and will hide their symptoms; after all, in the wild wolf pack, the sick and the weak jeopardise the survival of the strong. By the time you notice the signs that your dog is not well, it’s very likely that they have felt unwell for much longer.

In this article, we’ll explore the most common dog illnesses, what symptoms your dog may experience and what to do about your sick dog.

What are the most common dog illnesses?

Every day, veterinarians see dogs that have become ill – whether due to exposure to pathogens in their everyday lives, a progressive illness or ageing, poor lifestyle, or a genetic predisposition or hereditary disease. These are some of the most common dog illnesses (in no particular order) that vets may diagnose:

  • diarrhoea & vomiting
  • skin allergies
  • dental disease
  • kennel cough
  • ear infection
  • arthritis/degenerative joint disease

Diarrhoea and vomiting in dogs

There are many, many causes of vomiting and diarrhoea in dogs, so it’s no wonder that this is one of the most common reasons why pet parents bring their dogs to see the vet. Since dogs explore the world with their mouths and noses, this is where they pick up pathogens – from parasites like worms, to bacteria and viruses, and even toxins from plants and poisons. Any one of these, as well as food allergies and even a stressful event can make your dog vomit or have a runny tummy. A single bout of vomiting or diarrhoea is quite normal for a dog to experience from time to time, but if your dog has voided their stomach and is vomiting up bile, or has had diarrhoea for more than 24 hours, it’s time to see the vet.

Symptoms of GI tract upset

Aside from the obvious vomiting and diarrhoea, your dog may also experience:

  • abdominal pain
  • lethargy
  • loss of appetite
  • blood in the stool
  • vomiting foamy bile
  • fever
  • dehydration

How is the cause of vomiting and diarrhoea diagnosed?

The vet will ask questions about your dog’s behaviour and diet in the lead-up to their episode/s of vomiting and diarrhoea. This questionnaire will focus on what your dog may have eaten (whether they’ve begun a new type of dog food, raided the rubbish bin or have been given them table scraps) or experienced (such as a new pet in the home, having boarded at kennels, or another stressful event). From poisonous plants to pancreatitis to cancer – the vet will try to rule out every condition. They may do a blood test, faecal test and/or urinalysis and/or abdominal ultrasound to test for parasites or even an intestinal obstruction.

How is vomiting and diarrhoea treated?

The vet will initially want to restore hydration levels (which may mean oral rehydration or even IV fluids) and blood electrolytes. If the GI tract upset is due to a bacterial infection, the vet will prescribe antibiotics and anti-emetics (to prevent nausea and vomiting). Whatever the underlying cause of the vomiting and diarrhoea, the vet will prescribe a treatment plan to address it. In the meantime, your dog will need a short period of fasting before being reintroduced to bland, easily digestible food. Always follow the vet’s advice and treatment plan.

Skin allergies in dogs

Skin allergies – also called allergic dermatitis – present as red, itchy, inflamed and sometimes painful areas on your dog’s skin. If the allergy has caused your dog to scratch, they can experience hair loss and even secondary infection from bacteria entering through broken skin. Allergic dermatitis can be caused by your dog’s allergic reaction to types of food proteins, a reaction to flea bites, or environmental (atopic) allergies.

Symptoms of skin allergies

Depending on the cause and severity of the skin allergies, dogs may experience:

  • itching, scratching and chewing own skin
  • red, inflamed skin
  • licking and rubbing skin
  • hair loss (alopecia)
  • thickening of affected skin
  • warm, red ears/ear infection
  • GI upset (especially when caused by food allergies)

How are skin allergies diagnosed?

Your dog’s constant scratching may be annoying to you, but to them, itchy skin can become unbearable. Don’t wait too long before taking your dog to the veterinarian for a diagnosis and treatment. Make a note of when the itching and scratching commenced: if the symptoms started when your dog changed from one brand of food to another, then there may be a correlation with their diet (i.e. a food allergy). Similarly, if your dog’s itchy skin started at the same time as your hay fever, it’s likely to be an environmental allergy related to a change of the season. If necessary, the vet will do a blood test and/or a skin scrape test to narrow down what may be causing the dermatitis.

How are skin allergies treated?

The symptoms of the skin allergies will be treated to reduce the redness and inflammation, treat any infection, soothe the itching and restore skin health. If the cause of the dermatitis has been identified, this will be treated to prevent a recurrence of the symptoms. If it’s a food allergy, the vet will prescribe a hypoallergenic diet; if the itchy skin is the result of a flea bite allergy, the vet will prescribe a topical treatment and an anti-parasite regimen. Environmental allergens are more difficult to control, but follow the vet’s advice to ensure your dog’s symptoms can be adequately managed.

Dental disease in dogs

It is scary how many dogs (80%) will develop dental disease by the time they are two years old. Periodontal disease is characterised by damaged teeth, gums and bone due to oral bacteria that make themselves right at home in your dog’s mouth. Dental disease starts with gum inflammation (gingivitis) as the bacteria settle and tartar develops at or below the gumline. It’s not always obvious that your dog has a dental problem until the advanced stages of periodontal disease, when the tooth and gum damage become visible above the gumline. This is why it’s crucial to start a dental cleaning regimen with your dog as soon as possible – from puppyhood (to get them used to daily teeth brushing) or from today. Dogs can be positively conditioned to accept toothbrushing, but the next best thing is dog food that’s formulated to support dental health, dental chews, oral rinses and water additives that can help to keep your dog’s mouth clean. Speak to the vet about the best oral health support for your dog.

Symptoms of dental disease in dogs

  • bad breath (halitosis)
  • gum inflammation (gingivitis)
  • bleeding gums
  • receding gums, which indicate a loss of supportive structure around the teeth
  • loose teeth
  • tooth loss
  • reluctance to engage with chew toys
  • different eating behaviours – reluctance to chew kibble or preferring softer foods
  • unable to tolerate teeth being brushed

Where dental disease has reached an advanced stage, the oral bacteria can get into your dog’s bloodstream and begin to affect them systemically, attacking major organs like the heart and kidneys. This highlights the importance of good dental health for your dog.

How is dental disease diagnosed?

Ideally you should take your dog for an annual dental check-up. The vet will know what signs to look for, for the presence of gingivitis or periodontal disease. It is recommended that dogs have regular dental descaling and thorough teeth-cleaning procedures performed to protect them against the development of dental disease. The dog is placed under anaesthetic, which gives the vet the opportunity to look below the gumline for any tartar and to remove it before it causes damage to the dog’s teeth and gums. Dental disease can only be properly assessed and diagnosed during this anaesthetised procedure.

How is dental disease treated?

During a dental descaling and cleaning procedure, the vet will remove any tartar above and below the gumline and assess the health of your dog’s teeth. Loose and damaged teeth may need to be removed, and the remaining teeth will be polished to prevent bacteria from easily adhering to the teeth. Depending on the extent of infection, the vet may prescribe antibiotics and will recommend an at-home dental management routine for your dog.

Kennel cough

Kennel cough is the colloquial name for canine infectious respiratory disease (CIRD) or canine infectious tracheobronchitis. It is characterised by a hacking cough due to inflammation of the trachea (windpipe) and is highly contagious. It’s called kennel cough because the illness is usually contracted in an environment where there is a population of dogs in close quarters, such as at boarding kennels, the dog park, puppy school or an animal rescue organisation. If you suspect your dog has kennel cough, it’s best to confine them while you make an appointment with the veterinarian. While the disease (which can be viral or bacterial) usually resolves on its own, dogs with compromised immunity can develop pneumonia, so it’s best to see the vet, especially if your dog has a fever, becomes lethargic or experiences laboured breathing.

Symptoms of kennel cough

The symptoms of kennel cough can include:

  • a distinct hacking cough, as though something is stuck in their throat
  • runny nose
  • eye discharge
  • sneezing
  • fever
  • decreased appetite

How is kennel cough diagnosed?

The vet will perform a physical examination and ask about the history of your dog’s symptoms. Diagnosis can be based on a process of elimination – once the vet has ruled out more serious conditions like collapsed trachea, cancers, heart disease and other upper respiratory illnesses, they will recommend a treatment plan for kennel cough. It is not always necessary to perform diagnostic testing, except when the kennel cough may have progressed to pneumonia or if the dog has not responded to the treatment of the initial symptoms.

How is kennel cough treated?

Usually kennel cough will go away on its own after 10 to 20 days. During this time, the dog must be kept separate from other pets, and allowed to rest while you keep an eye on them. If the vet is concerned about secondary infection or the kennel cough progressing to something worse, they may prescribe antibiotics as well as medication to stop your dog from coughing. Keep your dog’s 5-in-1 vaccination up to date to protect them from kennel cough.

Ear infection in dogs

Dogs can develop ear infections for a range of reasons – from allergic reactions, to a build-up of ear wax and debris, to ear mites, and the dog’s ear/s not drying out after swimming. Hypothyroidism can also cause ear infections, as well as the growth of ear polyps and cancer. Ear infections can develop in the inner ear (otitis interna), the middle ear (otitis media) or in the outer ear (otitis externa). This segment refers to otitis externa – the part of the ear canal before the ear drum.

Symptoms of ear infection in dogs

An ear infection involves an inflamed, itchy ear canal, so the symptoms include:

  • itchiness in the ear canal
  • scratching and pawing around the ears and face
  • pain and redness in the ear (they may cry or whine if you touch their ears or head)
  • heat around the ear
  • yeasty odour
  • dark(ish) ear discharge
  • head-shaking
  • tilting the head

How is an ear infection in dogs diagnosed?

The longer an ear infection is left, the worse it can get and the more painful it may be for your dog, especially if an ear infection of the outer ear spreads deeper into the ear canal. If your dog shows any signs of their ears bothering them, make an appointment with the vet as soon as possible. The vet will take a look inside your dog’s ears – also employing the use of an otoscope if necessary – and take an ear swab and culture to look at the types of bacteria inside the ear canal. If the ear infection is severe, the dog may be sedated before the examination takes place.

How is ear infection in dogs treated?

The medications required to treat your dog’s ear infection will depend on the type of bacteria or fungus populating your dog’s ear canal (which is why it’s important to see the vet and not to try to treat the infection at home). Before sending you home with the right medication and pain medication, the veterinarian will attempt to remove as much of the debris, wax and/or parasitic residue in your dog’s ear. Part of the treatment will involve flushing the ear and a thorough cleaning of the ear canal. If your dog is in a lot of pain, they will be placed under anaesthetic in order for the cleaning procedure to be done comfortably for the vet and your dog. Follow all veterinary advice on at-home care for your dog’s ear infection.

Arthritis or degenerative joint disease (DJD)

Osteoarthritis or degenerative joint disease presents as stiff, swollen and inflamed joints where a dog’s joint cartilage has worn away. The dog experiences pain in their joints because of an absence of cushioning, the development of bone spurs, and friction between their bones. It is a progressive disease that gets worse as the soft tissue of the cartilage deteriorates and the joint becomes more inflamed. It cannot be reversed, but the progression can be slowed with supplementation and lifestyle management.

It is not only old dogs that develop osteoarthritis – sometimes younger dogs with other predisposing factors can also develop the condition. These include:

  • large or giant breed dogs
  • athletic dogs who participate in competitive dog sports (with the added risk of stress fractures and damaged ligaments)
  • dogs with genetically inherited dysplasia
  • overweight dogs with a lot more compression on their joints

Symptoms of osteoarthritis/DJD

Dogs will experience symptoms associated with less cushioning in their joints. These include:

  • joint pain and stiffness
  • joint swelling
  • difficulty getting up and lying down
  • more sleeping
  • reluctance to climb and descend stairs
  • muscle wasting
  • flinching at touch or brushing near or around the affected joints
  • inappropriate urination or defecation (i.e. inside the house)

How is osteoarthritis diagnosed?

Since most cases of osteoarthritis occur in older dogs, it’s important to take your middle-aged and senior dogs for an annual vet check-up. It’s during these appointments that the vet will begin to check for the early signs of arthritis and suggest the use of supplements like glucosamine, chondroitin and green-lipped mussel extract to slow the rate of degeneration of joint cartilage.

How is osteoarthritis treated?

As a progressive disease, osteoarthritis or degenerative joint disease cannot be reversed or cured, but the destruction of the joint cartilage can be slowed and the associated pain can be managed to ensure a good quality of life. The vet will recommend dietary changes for overweight dogs – they must lose weight to take the additional pressure off the joints and prevent rapid degeneration of the joint cartilage. It seems counterintuitive for a dog with joint pain, but dogs with osteoarthritis need daily moderate exercise. This will help to keep their joints mobile and to slow the muscle wasting that comes from reduced movement. A high-quality memory foam mattress will help to cushion the dog’s sore joints, and they must be kept nice and warm in winter to minimise pain and stiffness in the joints.


We may miss the initial signs and symptoms of dog illnesses, but as soon as your dog’s behaviour changes or they don’t act like their normal selves, it’s time to investigate. Thanks to an evolutionary survival tactic, dogs won’t show that they are feeling weak or sick until they just can’t help it, so it’s up to you to spot any signs that they’re unwell. With this in mind, it’s best to approach your dog’s health with a preventative mindset: keep their vaccinations up to date, maintain their tick and flea treatment and deworming schedules, and visit the vet annually for a general health check-up.