Parvovirus causes perhaps the most severe gastroenteritis in dogs, with a high fatality rate. It can affect any dog but tragically is often seen in puppies, with devastating consequences.
Parvovirus kills dogs because of severe gastroenteritis with vomiting, bloody diarrhoea, severe dehydration, shock and secondary severe bacterial infection. It is highly contagious and the virus remains infective in the environment for up to a year.
The virus is highly infective, liberated in very large numbers from the gut, and long lasting. Infection is by contact with infected faecal material. The virus can survive in the environment for months to years, although it is inactivated by sunlight and some disinfectants (such as bleach). It is clearly impossible to effectively disinfect a contaminated house yard, and very difficult even with kennels. Dogs can even carry the virus on their coat for extended periods. And humans who have been in contact with an infected dog can carry the virus on hands or clothes.
The incubation period of the virus (the time from exposure to developing symptoms) is 4-14 days. Dogs start passing the virus about 3-4 days after exposure, generally before symptoms develop. They excrete the virus for 7-10 days – most dogs have stopped excreting the virus by the time they recover from the diarrhoea.
The initial symptom is generally vomiting, combined with lethargy and failure to eat; diarrhoea, which is usually bloody, rapidly follows. Untreated, most dogs die in a few days from dehydration and infection. They suffer with abdominal pain, and the constant vomiting and diarrhoea cause dehydration, then death.
Parvovirus causes much more severe and long-lasting diarrhoea than other viruses because it attacks the cells from which the lining of the gut grows. Most other viruses just attack the most superficial cells, and these are rapidly replaced. It takes a number of days for the gut to grow a new lining after damage by parvovirus.
If started early treatment is successful in most cases, and recovered dogs are generally normal and suffer no long-term effects. Treatment involves intensive care with intravenous fluids, antibiotics, anti-vomiting drugs, and sometimes plasma or a blood transfusion. Treatment is expensive, but it is certainly worthwhile for many dogs.
Writing this it sounds all doom and gloom doesn’t it? Well, not quite. There are fantastic vaccines available for protection against the virus. Vaccination is almost 100% effective - puppies need a course of vaccinations from 6 weeks of age and adult dogs need regular boosters. Vaccination is cheap protection against this horrible disease which causes terrible suffering for dogs and very expensive treatment for owners.
Vaccination is highly protective –almost all dogs which develop parvovirus are unvaccinated or inadequately vaccinated dogs. Puppies less than 6 weeks of age are protected by antibodies absorbed from their mother’s first milk (colostrum) in the first 24 hours of life. This protection interferes with vaccination, and wanes from around 6 to 16 weeks. This is why we vaccinate puppies a number of times starting at 6 weeks of age and finishing at 16 weeks. The vaccine doesn’t work until the immunity from the mother wears off which can be different in each pup, but up to 16 weeks of age. Protection after 16 weeks is excellent with the modern high-potency vaccines.
It is important that you protect your puppy from sources of the virus (walking in public areas where infected dogs may have been) while they are undergoing their initial course of vaccines and building their immunity. Talk to your vet about ways to socialise your dog without the risk of exposing them to Parvovirus. Adult dogs only need to be vaccinated for Parvovirus every 3 years after they’ve had that initial puppy course.