Canine Parvovirus

Introduction: Parvo is a disease that causes great concern to both puppy owners and veterinarians. The reason for this concern is that parvo is very contagious and is often life threatening for the puppy or adult dog.

Puppies are the group most at risk for infection with parvovirus. The most severe infections usually occur in puppies less than 12 weeks of age. While all breeds of dogs may suffer from parvovirus infection, Rottweilers, Doberman Pinschers, and Staffordshire Bull Terriers (Pit Bulls) are particularly susceptible and more difficult to treat.

Causative Agent: Canine parvo is caused by a virus called canine parvovirus strain 2 (CPV-2). The virus is resistant to most common household disinfectants and cleaning agents. The most readily available exception to this is common household bleach (sodium hypochlorite), diluted to 1 part bleach and 30 parts water. This solution must be left in contact with the virus for a prolonged period (at least 10 minutes) to be effective.

Clinical Signs: Domestic dogs, coyotes, and other canids are susceptible to CPV-2 infection. The virus principally infects two main tissues: the digestive tract and the heart muscle. When the virus infects the digestive tract, the first clinical sign is usually vomiting, quickly followed by decreased appetite, lethargy, diarrhea, and dehydration. The stool may or may not have streaks of blood present. Death may occur as early as 2 days after the illness begins. When the virus infects the heart muscle, clinical signs include difficulty breathing, gagging, crying constantly, or sudden death.

Disease Transmission: This usually occurs from direct contact with infected dogs or contact with contaminated stool. Even minuscule amounts of contamination can be infective. A mere footprint left by someone who has had previous contact with an infected animal can spread the disease. Transmission can also occur in the womb if the pregnant female contracts the disease.

Diagnosis: Diagnosis is usually made with a quick in-hospital test (see page D621). Only a small fecal sample is required. It is important to note that some parvo vaccines will cause a mild positive result on many of these parvo tests. There are also blood tests and tissue cultures available for the detection of CPV-2.

Treatment: Treatment centers on immediate correction of dehydration and prevention of secondary infections. This involves administration of antibiotics and IV fluid therapy. Some dogs may also be infected with internal parasites that tend to complicate the recovery. When this is suspected, de-worming is often included in the treatment. Proper veterinary care and hospitalization are critical for puppies infected with CPV-2.

This puppy is suffering from a parvo infection. Many parvo dogs become severely dehydrated due to the great fluid loss from the vomiting and diarrhea. Maintaining proper hydration is a key to bringing a parvo dog into a full recovery. In this puppy’s case, IV fluids are being administered on a constant basis. Continual monitoring, testing, and round the clock medical attention is always essential.

Prevention: Vaccination with 2-3 boosters as a puppy, followed by annual boosters, is usually protective. The parvo vaccine can be given alone or in combination with other vaccinations. If a puppy or adult dog is suspected of having been exposed to CPV-2, the dog should be administered the parvo vaccine alone and not given a combination vaccine. Please refer to the vaccination program on page A905 for additional information. When a known infection with CPV-2 has occurred, disinfection of the environment (see above under causative agent) is essential to prevent the disease from spreading to other susceptible animals.