Parvovirus in Dogs

Canine parvovirus (CPV) infection or parvo first appeared in 1978, and the virus causing it is similar to feline panleukopenia (feline distemper). While the most significant strains are CPV-2, CPV-2a, CPV-2b, and CPV-2c, vaccines protect against them all, with CPV-2 and CPV-2c being the most serious. Luckily, diagnostic tests can detect all strains of the virus.

The virus’s primary source is the feces of infected dogs, which, when ingested by susceptible dogs enters their tonsils and/or lymph nodes. From there, it invades white blood cells called lymphocytes, carrying it through the bloodstream to many areas of the body, particularly the bone marrow and the lining of the intestines. Unlike most other viruses, CPV is stable in the environment, i.e., resistant to heat, detergents, alcohol, and many disinfectants.

Because of this, the virus is easily transmitted by the hair/fur or feet of infected dogs as well as from shoes, clothes, and any object contaminated by infected feces. A dog with parvo will usually start to show symptoms within three to seven days of infection. Early signs include lethargy, lack of appetite and fever. As the virus progresses, a dog may begin to experience abdominal pain, vomiting, and diarrhea. A very sick dog may collapse, have a high heart rate, have difficulty breathing, have a low white blood cell (WBC) count, be hypothermic and/or be hypoglycemic.

While parvo can affect dogs of all ages, it’s most common in unvaccinated dogs under the age of one. Puppies under the age of five months are usually the most severely affected and the most difficult to treat. For this reason, all unvaccinated puppies suffering from any or all of the above symptoms must be tested for CPV!

Fecal SNAP ELISA tests (enzyme-linked immunosorbent assay), otherwise called Parvo SNAP tests, are the most common way of diagnosing parvo in dogs and puppies. The test requires a fecal swab and takes about 10 minutes. While this test is usually accurate, a negative result doesn’t necessarily eliminate parvo in symptomatic dogs since they may not be shedding the viral antigen at the time they’re tested. In these cases, further testing may be required.

To date, there’s no way of killing the virus once it infects a dog. Although parvo doesn’t directly lead to a dog’s death, it causes the loss of the intestinal tract’s lining and weakens the immune system by affecting the white blood cell count. The intestinal damage results in severe dehydration, electrolyte imbalance and septicemia. If a dog develops septicemia, an infection of the bloodstream, that dog is more likely to die. (For reasons not fully understood, some breeds, notably the Siberian Husky, Alaskan Malamute, Rottweiler, Doberman Pinscher, Labrador retriever and American Staffordshire terrier have a much higher mortality rate than other breeds.) *

Treating dogs with parvo requires hospitalization with intravenous fluids that contain electrolytes. In severe cases, plasma transfusions may also be given and a feeding tube inserted if needed to focus on nutrition. Antibiotics and anti-inflammatory drugs are given to prevent or control septicemia, while anti-nausea drugs are used to stop any vomiting. Some vets may also recommend treatment with a canine parvo monoclonal antibody CPMA). The highest risk of death occurs around 24 to72 hours after dogs first exhibit symptoms of parvo, but if they receive the care they need and are monitored closely, the survival rate is usually about 85 –90%.

Vaccination is the best method of protecting your own dogs against CPV infection. Puppies receive a parvovirus vaccination as part of their multiple-agent vaccine series given at 8, 12 and 16 weeks of age. In some high-risk situations, vets will give the vaccine at two-week intervals with an additional booster administered at 18 to 22 weeks of age. After the initial series of vaccinations, boosters are required regularly. If, however, you use an approved three-year parvovirus vaccine, the next booster is routinely administered in three years.