Canine distemper virus: Serious but preventable

Canine distemper virus causes a potentially deadly, multisystemic disease in canids and can be hard to distinguish from canine parvovirus and kennel cough, writes veterinarian Allison Dascoli. Testing can help differentiate between the illnesses, according to Dr. Dascoli, but she notes that canine distemper virus can be prevented with proper vaccination. Charleston Daily Mail (W.Va.)

Canine distemper virus is a severe, highly contagious multisystemic virus that can affect dogs and other carnivores worldwide. We can see the virus in any dog, but it is most commonly diagnosed in young, unvaccinated puppies. This is especially true of puppies and dogs that are kept in close contact in kennels or shelters.

In these situations, the virus is spread by infected animals in all body secretions and excretions. But the most common way it is spread is through respiratory droplets and aerosol spray. Once the virus enters the body, it travels to the lymph system and on into the blood. Once in the blood, it travels back to the respiratory tract, GI tract and nervous system, causing clinical signs of the disease. Animals can shed the virus for up to two weeks after recovery if they are able to mount a sufficient immune response. If they are unable to fight the virus due to a poor immune system, they will die quickly.

The clinical signs of the virus are variable. Generally, these dogs will have a fever, go off feed and be depressed. The respiratory signs include nasal discharge, running eyes, coughing and sneezing. Pneumonia is a secondary side effect and can be viral initially and then change to bacterial. GI signs will include vomiting and diarrhea. Neurologic signs also can occur with or without other signs. The encephalitis that we see can include seizures, pacing, circling, problems walking, paralysis, vision issues and twitches. Some dogs can succumb to neurologic signs weeks to months after an apparent recovery. Other signs you can see are enamel defects on their adult teeth and hardening of the footpads.

Diagnosis of distemper can be difficult. The lifestyle of the pet has to be taken into account.  Older, vaccinated pets do not get distemper. Blood work is needed to look at blood cells and organ function to assess involvement. Chest X-rays can show pneumonia. The virus is only detectable for a certain amount of time in different tissues so sometimes a spinal tap is needed to collect fluid for analysis as well. But one of the better tests is called a PCR assay. It can be run on a blood sample, a conjunctival swab or on urine. These are all very expensive tests and multiple tests should be run to ultimately get to a correct diagnosis.

There is no effective antiviral treatment for canine distemper. Therefore all treatment is aimed at controlling the secondary symptoms. This includes broad-spectrum antibiotics, humidifiers, bronchodilators and expectorants to treat the pneumonia. Vomiting and anti-diarrheal medicine for the GI effects are given sometimes as necessary. Medicine to control seizures and excellent nursing care with fluids, cleaning the air passageways and balanced nutrition all help to support these patients.

The prognosis for distemper dogs is guarded. Mortality rates are the highest in younger animals and in animals that start to show neurologic signs. Even mild cases can appear to recover initially only to become clinical again.

Vaccination is the cornerstone in preventing canine distemper. The current American Animal Hospital Association guidelines for vaccines start at 8 weeks of age with a modified live virus vaccine and booster every four weeks until they are 16 weeks old. After the initial series, a booster should be given one year later, then every three years for life.  If dogs are older than 16 weeks when vaccination is started, booster after four weeks, then one year later, then every three years to ensure protection for life.

The problem with distemper is that it can look like kennel cough and also like parvo, which are very common diseases we see in shelters. If you suspect distemper, immediately talk to your veterinarian. They will recommend testing to try to determine the disease. In all cases, you will need to isolate the pet and clean the environment well with disinfectants until you can get a diagnosis and a treatment plan started.

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