Canine Parvo Virus

History

Canine parvovirus was discovered in 1967 and originally did not represent much of a medical threat except to newborn puppies However in 1978, a new variant, CPV-2 appeared in the U.S. This newer version represents a mutation from the feline distemper virus. This new variant is shed in enormous numbers by the infected animals. It is very hardy in the environment and is extremely aggressive once contracted, dividing rapidly in the host’s intestine, bone marrow and lymphatic cells. The current form of the virus is ubiquitous with virtually all dogs exposed to it to some extent.

How is it contracted?

Puppies and dogs usually become infected when they ingest virus that is passed in the feces of an infected dog. Canine parvovirus is so resistant to environmental conditions it can survive up to 5 months. Trace amounts of feces containing parvovirus may serve as reservoirs of infection and the virus is readily transmitted from place to place on the hair or feet of dogs or via contaminated cages, shoes, or other objects.

What are the clinical signs?

There is a 3-7 day incubation period before the animal becomes ill. Once in the body the virus first attacks the immune system, causing the white blood cells to drop and then over 3-4 days it invades the bone marrow and intestine. Clinically the animal will first show weakness and depression followed by vomiting, diarrhea and death. Death is caused by the extreme fluid loss from the vomiting and diarrhea or from the septic toxins and bacterial invasion due to loss of the intestinal lining.

How is it diagnosed?

Initially the clinical signs are similar to other possible diseases or parasites. Diagnosis depends on watching for the GI signs and running the parvo elisa snap test. This test detects virus in the stool and is very sensitive. Other blood tests such as a CBC which shows a low white blood count can also help.

What is the recommended treatment?

Treatment is all about support and allowing the animal’s immune system to clear the virus. This usually takes 5-7 days of intensive care in a hospital to occur. Support consists of IV fluids, antibiotics, anti-vomiting medicine, anti-diarrhals , immune boosters and anti-virals (new). Survival is usually around 50-70% depending on severity and breed.

How can it be prevented?

Vaccination is the best option for prevention. The problem with vaccination is that material antibodies from nursing inactivate the vaccine. This requires multiple vaccinations (ie: boosters) to be given to attain immunity. We recommend vaccination starting at 6-8 weeks then every 3 weeks till 16weeks of age. It should be noted that giving vaccines more frequently than every 2 weeks will cause interference between the two vaccines and neither can be expected to be effective. There is no true magic number of vaccines needed to obtain immunity. In order for protection to be achieved, the vaccine must simply be given when it can penetrate maternal antibody.

How should infected areas be cleaned?

Bleach is the best and most affective disinfectant for parvovirus. 1/30 parts water on all hard surfaces and bowls is recommended. The virus will last one month on carpeted surfaces so isolation is the best option.