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UI College of Veterinary Medicine

Parvovirus, commonly known as "parvo," is a contagious virus that can be very serious and even fatal in dogs. Dr. Jennifer Reinhart, a small-animal internal-medicine specialist at the UI Veterinary Teaching Hospital in Urbana, explains that parvo is a problem that can be seen in dogs of any age.

"Although there is a window of highest risk between 8 and 16 weeks, adult dogs that are not correctly vaccinated may contract this virus as well," Reinhart said.

Patients that are diagnosed with parvovirus usually have vomiting, diarrhea, lack of energy and poor appetite.

Parvovirus targets the gut cells of the dog. That is why patients have vomiting and diarrhea, which may lead to dehydration or starvation, due to a lack of nutrition staying in the body. The virus also attacks bone marrow cells, which causes problems in the immune system.

"When the virus attacks the immune cells in the bone marrow, the patient becomes more susceptible to secondary infections," Reinhart said.

The cycle

Parvovirus is found in the environment and can be contracted by a susceptible dog in various ways. The cycle begins when the virus is shed in the feces of an infected dog. Another dog may contract the virus by coming into contact with infected feces or dirt that contains the particles of the virus. Even if the infected feces were promptly picked up, infective virus remains on the ground.

"Parvo is a very hardy virus. It can persist for weeks to months in the environment," Reinhart said.

The virus will be present in feces even before the infected dog shows clinical signs of the disease. What's more, a dog that had parvovirus can continue to shed the virus in feces for up to eight weeks after getting better. Some infected dogs never develop clinical signs but do continually shed the virus.

"Parvovirus is everywhere, and you cannot 100 percent prevent exposure," Reinhart said. "The best thing to do is to make sure that your puppy is properly vaccinated."

Preventing parvovirus

Although the vaccine series cannot guarantee absolute protection against the disease, it offers the best chance at avoiding parvo. An animal that is appropriately vaccinated has a much lower chance of contracting the virus.

Reinhart stressed that the vaccine series isn't complete after the initial 16-week series of shots. "The boosters are what actually complete the vaccination series," she said. "A booster given at one year, and then every three years after that. Only then is a dog considered appropriately vaccinated."

Another important preventive measure is avoiding exposure to dogs that might have parvo.

"During the period when puppies are most susceptible to the virus — between eight and 16 weeks of age — puppies should not be interacting with other dogs. It is the best way to keep them safe," Reinhart said.

What if it's too late?

Although parvovirus can be a very scary thing, it is definitely something that can be cured. Reinhart said that a patient with parvovirus that is treated properly has a very good chance of surviving.

"If the disease is caught early enough, and the animal is able to receive aggressive supportive care, its chance of survival is actually really good," she said.

Supportive care includes aggressive fluid therapy and antibiotics. In some cases, a feeding tube is placed.

"The antibiotics are for protecting the patient from secondary infections, and the feeding tube is sometimes placed in order to give the nutrients the patient needs if it isn't eating on its own," Reinhart said.

The antibiotics are crucial because the virus attacks the immune cells in the bone marrow, suppressing the immune system of the patient.

"In a big picture sense, it is very easy to prevent your dog from getting parvovirus," Reinhart said. "It's important to keep your pet up to date on vaccinations and do your best to avoid exposure to infected dogs."

If you have any questions about parvovirus or believe your dog is due for vaccinations, contact your veterinarian.

An archive of pet columns from the UI College of Veterinary Medicine is available at Requests for reprints of this article may be directed to Chris Beuoy at