Effectiveness of Canine Parvovirus Vaccinations in Puppies

Parvovirus takes the form of severe, often bloody, diarrhea. It is highly contagious and easily spread through direct contact between dogs or through the feces of infected dogs and puppies. The virus can remain viable for months on contaminated surfaces. Parvovirus can last for up to one year in the soil. The parvovirus vaccine is one of the first given to puppies because the virus is so hardy in the environment and so dangerous to unvaccinated puppies.

Several types of canine parvovirus exist. The most recent strain of parvovirus is known as CPV-2c, the third and currently most common strain of the virus that has been identified in the United States. All strains of parvovirus will cause anorexia, vomiting and diarrhea that may or may not be bloody. Dehydration will often accompany the other symptoms. Very young puppies hearts also may be affected. Although all dogs can be infected with any of the parvovirus types, unvaccinated dogs and dogs under the age of 4 months are most at risk.

The most commonly used parvovirus vaccines are produced using a modified live virus. The modified live vaccine cannot be used in dogs with compromised immune systems. A killed virus vaccine is also available. The dog or puppy is vaccinated under the skin starting at the age of 6 weeks.

Puppies begin their lives protected by their mothers’ antibodies. The vaccines are only effective after their mothers antibodies begin to fade from their system. No specific vaccine exists for the CPV-2c virus. However, the vaccines for the previously known types of parvovirus are also effective for the CPV-2c virus. Although vaccines can protect a puppy or an adult dog from the parvovirus, not every dog is fully protected even when fully vaccinated.

It is best to vaccinate puppies and adult dogs and to take other steps to prevent parvovirus rather than to treat it. Treatment of affected dogs consists of providing fluids and electrolytes, as well as controlling symptoms such as nausea, vomiting, or diarrhea. Affected animals also may be susceptible to secondary infections, so a clean environment is needed. Isolation of affected animals also may be needed to prevent infecting others. Treated dogs may have an 85 percent chance of surviving parvovirus. By contrast, the mortality rate can exceed 90 percent in untreated dogs.