Introduction
When an owner notices weepy eyes, nasal discharge, coughing, vomiting, diarrhea, lethargy, weakness and/or lack of appetite and weight loss in a young dog – especially in one who is unvaccinated or has not completed its puppy series of vaccinations – distemper should be fairly high on the list of differentials, and the dog should be taken to the veterinarian as soon as possible. It is not especially difficult to diagnose distemper in domestic dogs, although it does require a series of tests, because several other disorders can mimic the signs of distemper, including canine parvoviral infection, canine infectious tracheobronchitis and other infectious or inflammatory diseases.
How Canine Distemper is Diagnosed
Most veterinarians presented with a sick puppy will draw blood for a complete blood count (CBC) and serum biochemistry panel, which can provide a great deal of information about infection, organ function and overall health. A urinalysis is also routinely performed. Thoracic radiographs (chest x-rays) may be taken and may reveal early stages of distemper and associated pneumonia. There are advanced blood tests that can identify antibodies to the distemper virus. However, these may not be particularly helpful, because they cannot distinguish between recent or current infection with the distemper virus and antibodies that developed from vaccinations.
The best way to definitively diagnose canine distemper while the dog is alive is a fluorescent antibody test. This can be performed on a number of samples, including blood, respiratory or tonsil samples, cerebrospinal fluid, bone marrow or urine. If caught early enough, samples taken from the conjunctiva of the eye early in the disease can be diagnostic using a fluorescent antibody test. Some veterinary teaching hospitals and other laboratories offer what is called a polymerase chain reaction test, or “PCR” test, for distemper virus in blood samples taken from domestic dogs. These tests are quite reliable. The absolutely most reliable way to diagnose canine distemper is done postmortem via a necropsy (which essentially is an autopsy conducted to examine the body and determine the actual cause of death.
Special Notes
Routine “puppy vaccination series” have gone a long way in the United States and elsewhere towards decreasing the incidence of distemper. Canine distemper is a particularly nasty disease: it is highly contagious, causes severe symptoms and can kill affected animals, especially puppies, within a matter of weeks. It is important for owners of new puppies to consult with their veterinarian about proper vaccinations for their new family member, and to follow through with their veterinarian’s recommendations. No one wants their pet to get distemper, or to spread it to other animals. The vaccination against this disease is very effective and is routinely given as part of the standard recommended puppy vaccination protocol.