Parvovirus in Puppies

Group of Jack Russell terrier puppies

Vaccinations can prevent many illnesses in puppies, but viruses such as canine parvovirus are still a threat to dogs with developing immune systems. Young puppies often have immunity against the virus because they get antibodies from the colostrum in their mother’s milk, but these antibodies are not always as effective as a vaccine.

Dr. Johanna Heseltine, clinical assistant professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, explained the characteristics of parvovirus. “Canine parvovirus, or ‘parvo,’ is a highly contagious virus that affects dogs and often causes severe diarrhea and vomiting in puppies,” she said. “Parvovirus lives for months in the environment, so many puppies can be exposed while their immune system is still vulnerable. Once dogs are fully vaccinated, they seldom become infected. Even if a puppy has received some vaccines, they are still at risk for infection because the antibodies they receive from their mother’s milk can interfere with the puppy’s immune response to the vaccine. In addition to this, the puppy’s body has not made its own protective antibodies.”

Parvovirus attacks areas of the body where cells are rapidly dividing, such as the intestinal tract and bone marrow tissue. As a result, victims of the virus experience a loss of appetite, vomiting, diarrhea, weakness, and lethargy. “Since the virus attacks white blood cells in the bone marrow, infected dogs develop low white blood cell counts, which puts them at risk for a bacterial infection called sepsis,” said Heseltine. “The severity of illness varies between patients, but most of the dogs we see in the hospital develop severe bloody diarrhea and vomiting.”

Parvovirus spreads through fecal-oral contact, meaning the virus can be transmitted through any animal, person, or object that comes in contact with an infected dog’s feces. A dog can shed parvovirus in its stool without showing any signs of illness and can continue spreading the virus for several weeks after recovering. Parvovirus is so common that it may be present anywhere that dogs frequently visit. Inanimate objects, such as food bowls, shoes, clothes, and carpet also serve as carriers for the virus for up to several months.

Treatments for parvovirus are available, but prevention through vaccination is essential to protect puppies’ health. If infected, puppies should be hospitalized and isolated from other dogs to avoid spreading the disease. Large amounts of bodily fluids are lost through vomiting and diarrhea, so patients are replenished with electrolytes through intravenous fluid therapy. Antibiotics are also needed to help prevent secondary infections. Other treatments include antiemetic medication, plasma transfusions, or related therapies.

You can protect your puppy from this deadly virus by making sure they stay up-to-date on vaccinations. Limiting your puppy’s exposure to other dogs, as well as keeping a secure backyard that prevents strays or other potentially infected animals from entering will also decrease the puppy’s risk of contracting the disease. Until your veterinarian declares it is safe, try keeping your puppy away from dog parks or other areas where there is a high concentration of dogs.

If you think your puppy may be infected with parvovirus or has come in contact with another infected animal, contact your veterinarian for assistance. To prevent further spread of the disease, it may be necessary to remove your puppy’s toys, blankets, and other belongings from the environment.

Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the Web at Suggestions for future topics may be directed to

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