Canine ParvoVirus

Canine ParvoVirus

Parvo – the most awful illness

 It seems like nearly 3 decades ago when I first saw a pup affected by parvoviral infection. The forlorn and sad face of a lethargic puppy, stricken by waves of nausea, vomiting & diarrhoea, I will never forget.

And 25 years later, I still treat puppies afflicted by this terrible illness. We can do better now, what with modern medicines and intensive care – but, the suffering occurs on our watch. It is heartbreaking to see these little pups simply waste away under the ravages of this nasty viral disease.

Parvovirus first surfaced in dogs around 1978, and it is thought to have jumped from a feline parvoviral infection. Now feline and canine virus are their own species, and although feline enteritis (or panleucopaenia) is uncommon, cases of canine parvovirus occur with too regular frequency.

This virus is a tough little nut. It survives in the environment, some say for up to 2 years. It can be carried on your shoes or clothing and remain infective to your pet. I have seen pets with infection that have never left their yard.

The virus enters the body through the mouth and localises in the lymph nodes initially. It then attacks rapidly growing cells, usually in the bowel, although in very young patients, the heart is also susceptible. The other main target organ is the bone marrow – responsible for production of red and white blood cells.

As it multiplies within cells, it bursts the cell open, stripping the cells away from the bowel. The small intestine wall is normally folded quite closely, forming little valleys (crypts) and mountains (villi). As the virus attacks, the crypt cells are damaged and the villi are denuded or lose their cells, allowing plasma and blood and fluids to enter the bowel, and allowing bacteria to march through the gut wall, and into the blood stream.

In addition to the fluid losses, which can be massive, now the bacteria attack. Because the bone marrow is harmed and there are no armies of white blood cells to fight back, the immune system is quickly overwhelmed and life threatening sepsis develops. If left untreated, the pet will succumb and die of dehydration and infection.

Treatments are intense and involve long hospital stays with many avenues of treatment, including fluid therapy, antibiotics, gut protectants, and in many cases, plasma or blood transfusions. Treatment aims to support the body while the medications fight off the disease. And with intensive (& often expensive) treatments, the results can appear miraculous – success rates of >90% are usual.

But while we could take this path, the more sensible and effective approach is to ensure our pets remain protected by vaccination. A series of vaccination starting at 6-8 weeks of age for puppies, and ensuring vaccination continues into adulthood, provides our best chance of success against this deadly disease.

Parvovirus infection and illness is a common and deadly consequence of lack of vaccination. Pet owners should be vigilant to ensure their pets are protected, and investigate fully the vaccination history of any potential new dogs coming into a household.