Parvovirus disease in your dog

Parvovirus enteritis is a serious viral infection of the gastrointestinal tract mainly affecting young dogs. The virus attacks the cells of the gut resulting in vomiting and profuse diarrhea. Parvovirus also suppresses the immune system and causes a profound decrease in the white blood cell numbers circulating in the blood. For severe cases, severe inflammation and clotting issues can progress into organ failure.

The management of parvoviral enteritis includes intravenous fluids and supportive treatment.

©Douglas McCallum

Parvovirus is a small virus that attacks young dogs and infects their intestines. It destroys the cells that line the intestinal lumen and causes vomiting and very severe diarrhea that is often bloody. Large numbers of virus particles are shed in the feces of infected dogs and may infect pups, especially those that have not been vaccinated or have not completed their vaccine course. The virus can be resistant in the environment and transmission of the virus can occur if no preventive action is implemented.

Dogs that are infected usually develop signs of the disease 4-7 days after they are exposed to the infecting virus. Infection is usually a result of eating infected material, mostly excretions from infected dogs. The initial signs of infection are listlessness, anorexia (failure to eat) and vomiting. The disease progresses to dehydration, diarrhea and severe lethargy. Infected dogs may develop a state of shock due to dehydration or secondary bacterial infection and eventually die.

Your veterinarian will probably suspect that your dog might have parvoviral enteritis from the symptoms that you describe, the dog’s vaccination history and the findings on physical examination. A blood test may show a severe decrease in the white blood cell number and diagnosis can be confirmed by tests that detect the presence of parvovirus in the feces.

In the United States there is a monoclonal antibody treatment available, but in many localities there not yet a direct treatment against the virus. Therapy is “supportive” and consists mainly of injecting the dog with fluids and electrolytes via a vein in order to compensate for dehydration and correct for on-going losses of fluid by vomiting, diarrhea and the refusal to drink during the disease. In addition, dogs are often also treated with drugs to stop vomiting, prevent gastric ulceration, and with antibiotics, to prevent secondary infection with bacteria. Fecal matter transplant may help some dogs recover quicker.

There are some human drugs that have been used in dogs with parvovirus. These are often very expensive and, in many cases, there is not much good information on their benefits. If your dog has parvovirus your vet may want to discuss these treatments with you.

If disease is diagnosed early (before your dog deteriorates severely) and appropriate medical treatment is given, your dog has a good chance of survival. However, some dogs do not survive despite proper medical care and early diagnosis. The disease appears to be more severe in young pups and in those that have had no vaccination against parvovirus or have only just begun their vaccination course.

It is essential to vaccinate your dog according to your veterinarian’s recommendations. Pups that are born to vaccinated dams usually have antibodies from their mothers (maternal antibodies) that protect them against infection during the first few weeks of their lives. The pup is in danger after the level of maternal antibodies declines in his blood and that is when he should be vaccinated. Maternal antibodies prevent active vaccination, therefore a vaccine should be injected when the maternal antibodies are no longer protective and that time differs between pups. The vaccination is repeated in order to make sure that the dog has had an effective vaccine dose and to boost this effect. Additionally, dams can be vaccinated before they become pregnant.

To prevent the spread of infection, sick dogs should be isolated from other dogs and cages and pens should be properly disinfected and cleaned. Pups who have not completed their vaccination schedule should be prevented from any exposure to potentially infected animals or their environment.

Some breeds of dog may need different vaccination protocols. Your veterinarian will be able to advise you on which vaccinations your dog needs.