Throughout spring and early summer, the CSU Veterinary Teaching Hospital emergency and urgent care service sees on average two to four cases per week of puppies with parvoviral enteritis, or parvovirus, an easily transmissible DNA virus that causes severe vomiting and diarrhea. As the weather warms up and spring rings in puppy season, exposure and transmission increase with the new crop of unvaccinated dogs and more frequent visits to public spaces like dog parks.

“Parvovirus is really hearty and can live in a contained environment like a yard for up to eight months,” said Dr. Amanda Cavanagh, an emergency care veterinarian at Colorado State University’s Veterinary Teaching Hospital. “It’s easily passed by dogs shedding it into the environment, and then other dogs pick it up and get sick.”

Parvovirus infects cells that divide quickly, and the fastest dividing cells in the body are the intestines, so it destroys the intestinal lining, leading to vomiting, diarrhea, weight loss, lack of appetite, and dehydration. Other rapidly dividing cells are white blood cells, so the virus also targets those, giving animals a low white blood cell count. Without ample white blood cell supply, the body cannot adequately fight off other infections, making ill puppies unable to overcome infection without significant medical intervention.

Treatment for parvovirus is intensive and time consuming. Inpatient treatment includes consistent fluid therapy via an IV to maintain hydration, anti-nausea medication to curb vomiting and encourage appetite, and antibiotics to prevent secondary infections. CSU faculty published an outpatient protocol in 2016, which consists of similar treatment that can be administered by owners at home, instead.

Survival rates of parvovirus with treatment are variable – ranging from 50% to 92% – and the key to survival is seeking early treatment, before the animal becomes profoundly dehydrated. Outpatient treatment typically costs several hundred dollars, while in-hospital treatment can range anywhere from $2,000 to upwards of $10,000 if the dog is severely ill and requires hospitalization or even blood transfusions.

Vaccination is your puppy’s best chance of survival

To give any puppy – and your wallet – the best chance of survival, though, is to keep up with regular vaccinations.

“The most tragic thing is it’s very preventable. We have a great vaccine,” Cavanagh said. “Even though parvo has mutated over decades to more severe disease-causing strains, the vaccine still works for all mutations that have happened over time.”

Puppies can receive their first parvovirus vaccine at around six weeks old and should get a booster every two to four weeks until they are four months old. Older puppies can still start their vaccination schedule but may receive fewer total injections.

“The key with young puppies is you continue vaccinating them as their mother’s antibodies go away,” Cavanagh said. “You’re building your puppy’s own immunity with those additional doses.”

While puppies that nurse from their mother will get antibodies that will last about four to six weeks, formula-fed puppies are not protected from parvovirus. If the mother never had a vaccine or exposure to the virus, her puppies also would not have immunity to protect them in young infancy.

Minor reactions to the parvovirus vaccine can occur, like itchy skin or vomiting (both easily treated with Benadryl), but there are no known long-term complications. Once a puppy is fully vaccinated, they are free to go hiking, visit a dog park, ride in the car, or go to a restaurant with their owner.

Dogs are fully protected from parvovirus for life as long as they get a booster every three years. Primary Pet Care at the Veterinary Teaching Hospital includes the parvovirus vaccine with its core vaccines, available as part of their wellness plans for dogs.