Sick Dog Symptoms & Diagnosis

Updated July 19, 2017

Keeping a dog safe and healthy is the responsibility of all dog owners. Many health issues for dogs can be prevented with good care and a watchful eye. The most basic symptoms of illness include changes in behaviour such as lethargy, restlessness or aggression, anorexia, fever, whining, laboured breathing and excessive itching. There are common dog illnesses and symptoms to look for.

Internal Parasites

According to Purdue University, parasites can affect dogs at any age. Common symptoms of internal parasites include lethargy, poor growth in puppies, dull coat, pot belly, vomiting and diarrhoea. Severe infestations can cause seizures. The main diagnosis is through a fecal check for parasites and their eggs. Blood tests may also be required, especially if the dog is being checked for heartworms. Heartworm tests should be conducted regularly.

External Parasites

External parasites can be quite common in dogs, especially flea and tick infestations. Symptoms of external parasites include scratching and chewing at skin; scabs; skin discomfort; raw patches of skin; and hair loss throughout the coat and around the eyes. You might also be able to see the parasites. A veterinarian will diagnose your dog by examining its skin and coat.

Infectious Disease

Common infectious diseases in dogs include canine caronavirus, rabies, distemper, hepatitis, leptospirosis and kennel cough. Symptoms of these diseases include fever, vomiting, anorexia, diarrhoea (possibly with blood), jaundice, coughing, runny eyes, laboured breathing, tissue swelling, haemorrhage and behavioural changes. Your veterinarian will diagnose these diseases through physical exams and blood tests. Not all infectious diseases have an accurate test for diagnosis, however. Keep in mind that many of these diseases can be life-threatening.

Ear Infections

Any dog can get an ear infection, but those with a heavy ear flap are more prone to ear problems. Ear infections can be caused by bacteria, parasites or yeast. Symptoms of ear infections include scratching at ears, discharge from ears, pain, swelling or redness in the ear canal, head shaking and a strong odour from the ear. A veterinarian will examine the dog's ears for infection and may take a swab to collect discharge for analysis.

Dental Problems

Symptoms of dental problems include foul breath, drooling (possibly with blood), and attempts to eat that result in dropping food and crying in pain. The vet will diagnose dental issues through a physical examination of the mouth and possibly radiographs or culture swabs taken from the mouth to test for bacterial growth.


According to the University of North Carolina at Charlotte, bloat is a life-threatening emergency for dogs. Symptoms include pacing, restlessness, resting in unusual places, drooling, vomiting or retching, panting, whining, agitation and possibly abdominal bloating. Diagnosis may require a physical examination, radiographs and stomach aspiration.

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About the Author

Based in Colorado, Jacqueline Lerche has been writing alternative health, natural science and environment-related articles since 2009. Lerche holds a Bachelor of Science in biology and an Environmental Affairs Certification from Colorado State University.