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July 17, 2019 – In 1978, fear gripped dog owners around the globe. A deadly disease was spreading like wildfire among dogs, regardless of age, breed or sex. The disease, characterized by bloody diarrhea, vomiting, dehydration and shock, caused widespread illness and death, especially in puppies. Veterinary researchers quickly mobilized to look for a cause and they soon identified the culprit - a tiny intestinal virus that likely arose from a mutation in feline panleukopenia virus. The pathogen is now known as canine parvovirus.

An effective vaccine was soon developed and was continually refined over the next 10 years. Although massive outbreaks of the disease are a thing of the past in the United States, the virus is still very much with us and remains a major cause of death in young dogs. It’s important for owners to know the latest about canine parvovirus and what you can do to protect your dogs from this terrible disease.

How it Spreads

Canine parvovirus is shed in feces and can survive in the environment for up to one year. Dogs are infected when they encounter the virus either in infected stool, in the environment (which includes objects such as toys, shoes and bowls) or in the vomit of infected dogs. Infected dogs will shed virus for a few days before they become sick and for an additional seven days after they start showing signs.

The incubation period for the virus is one to two weeks, although there are scattered reports of incubation periods as short as four days. Canine parvovirus needs rapidly dividing cells for growth; these include the cells lining the intestinal tract and the bone marrow.

Viral invasion causes massive cell destruction and accounts for the most common signs we see in dogs infected with canine parvovirus – diarrhea, vomiting and low white blood cell counts. The destruction of the intestinal cells also makes it easier for the bacteria that live in the gut to enter the bloodstream, a serious condition known as sepsis. The lack of white blood cells to fight the infection compounds the problem. The disease can then spiral out of control, resulting in death.


Diagnosis of parvovirus infection is fairly straightforward. Low white blood cells counts are a good clue pointing toward the diagnosis, especially when coupled with vaccination history. There are several quick in-house tests that are very helpful for rapid diagnosis, although occasionally these can miss a case of parvoviral disease; however, false positive results of these in-house methods are uncommon. As a backup, some tests are available through large diagnostic laboratories that are even more accurate, especially in ambiguous cases.

Treatment & Recovery

Canine parvovirus infections are treatable but costly. Estimated survival rates range from only 9% in untreated puppies to greater than 90% in puppies treated aggressively in specialty or teaching hospitals. Experts feel that if a patient survives the first three or four days of treatment, chances are good they’ll make a complete recovery.

Although most dogs have no life-long effects after recovery, one recent study looking at survivors of infection found that almost one-half suffered from some chronic gastrointestinal signs later in life (as reported by their owners). The authors couldn’t draw any conclusion regarding why these dogs might have a predisposition to gastrointestinal issues. More investigation is needed to determine what link, if any, exists between a past infection and long-term problems.


The good news for dog owners is that vaccination is very effective at preventing infection. In addition, dogs that survive natural infection likely develop livelong immunity. There also are other measures important for dog owners to take to prevent exposure to parvovirus. These include keeping young dogs isolated until they finish their puppy vaccinations, keeping young dogs in clean environments and, of course, making sure that puppies and adult dogs with unknown vaccination status complete a full series of vaccination against parvovirus.

How We Are Helping

Morris Animal Foundation played a pivotal role in providing funding to researchers on the front lines of the initial canine parvovirus outbreak and we’re proud of our contribution to help save the lives of millions of dogs around the world. We continue to fund emergent diseases in many species, from the current outbreak of goat plague that is pushing the Mongolian saiga toward extinction to the recent re-emergence of feline panleukopenia virus.

Learn more about how you can help us respond to these emergencies and help all animals have longer, healthier lives.