Canine Parvovirus


Canine parvovirus is a very contagious and unfortunately a common cause of illness in young dogs.  It is a viral infection that kills the cells lining the small intestines in puppies and unvaccinated adults.  Humans and cats are not thought to be at risk of infection.

How does my dog become infected with parvovirus?

Parvovirus is transmitted via the fecal-oral route.  Unvaccinated or incompletely vaccinated puppies and dogs are at the highest risk of infection.  Dogs who are infected can start shedding the virus in their feces even if they are not showing any clinical signs.   A susceptible dog becomes infected when they ingest the virus after coming into contact with infected feces or any contaminated surface. 

Canine parvovirus is very stable and can survive for more than 7 months in the environment.  It is also very difficult to kill and is resistant to most disinfectants.   Because of this, the virus can easily be transmitted via the hair coat of infected dogs and on the shoes or clothing of humans. 

What are the clinical signs of parvovirus?

Clinical signs usually present 3-14 days after exposure and usually include lethargy, anorexia, vomiting, and diarrhea (with or without blood).  Many dogs do not show every clinical sign, but vomiting and diarrhea are the most common.  The virus can affect dogs of all ages, but is generally seen in unvaccinated or incompletely vaccinated dogs. 

How is the disease diagnosed?

There are many diseases that can cause vomiting and diarrhea.  However, parvovirus should always be suspected in any young, unvaccinated or incompletely vaccinated dog with clinical signs.  There is a quick, in-house test available that screens for the disease using a stool sample.  Because it tests for viral particles in the stool there can occasionally be a falsely negative result if the dog is not yet shedding the virus. 

How will my dog be treated?

Unfortunately, there is no medication to kill the virus and therapy is aimed at supportive care.  The virus attacks the intestinal tract and causes severe dehydration, sepsis, and electrolyte imbalances.  Therefore the mainstays of treatment are to prevent sepsis, correct electrolyte imbalances, normalize blood pressure, pain control, and to stop the presenting clinical signs.  Labwork is performed to monitor white blood cell counts, electrolytes, and organ function and give better prognostic values.  It is recommended that dogs be hospitalized and treated with aggressive IV fluid therapy, antibiotics, and medications for pain and vomiting.   The prognosis is good for dogs that receive the recommended care and who do not suffer from any complications of the disease.  According to one source, there is a 93-95% success rate in severely ill dogs that are hospitalized and treated. 

How can I protect my dog from parvo?

The best way to protect your dog is by having them properly vaccinated.  Parvovirus vaccines are a part of the core puppy vaccination series.  It should be given starting at 8 weeks of age, and is boostered every 3-4 weeks until the puppy is 16 weeks of age.  It is important to know that a puppy is not fully protected until they have completed the vaccine series, which may take even longer if some vaccines are missed or skipped.  Until a dog is fully vaccinated, they can still become infected if they come into contact with contaminated feces or surfaces.  The vaccine is then boostered at regular intervals in their adult lives, and the schedule should be discussed with your veterinarian. 


Côté, Etienne. Clinical Veterinary Advisor. St. Louis: Elsevier Mosby, 2011.  Print.

Mitchell, Kelly.  “Canine Parvovirus.”  The Merck Veterinary Manual, March 2012.  Web.  3 January 2015. 

Ward, Ernest. Parvovirus in Dogs.  Lifelearn Inc, 2011.