What every technician should know about parvovirus (Proceedings)
Canine Parvovirus (CPV) is a family of viruses that cause vomiting, hemorrhagic diarrhea, and leukopenia. The virus can infect dogs of any age but, because of effective client education and early, aggressive vaccination protocols, is commonly noted in dogs less than 1 year of age. There are currently 2 active variants of the virus in the United States - CPV-2b and CPV-2c – of which the latter is the most recent and most virulent to appear. CPV infection is acquired by the fecal-oral route. Initial viral replication occurs in extra-intestinal lymphoid tissues, where the virus is spread through the blood to other lymphoid tissues where the cycle is repeated, eventually resulting in intestinal epithelial infection. The virus then localizes to the crypt epithelium, bone marrow, and other lymphoid tissues, where it produces intestinal crypt epithelial cell necrosis, leukopenia, and lymphoid destruction and depletion.
Patients suspected of being infected with Parvovirus are commonly young dogs (age 6weeks to 6 months) of any breed that are under-vaccinated. Presenting signs include vomiting, diarrhea that is commonly hemorrhagic, and anorexia. Initial triage examination findings commonly include hyperthermia or hypothermia, tachycardia, altered pulse quality, tachypnea, evidence of dehydration, abdominal discomfort, along with the vomiting and diarrhea.Initial biochemical abnormalities commonly found in patients suspected of being infected with canine Parvovirus include leukopenia/neutropenia, hypoalbuminemia due to enteric losses, azotemia due to dehydration, hypokalemia, and hypoglycemia. Due to decreased perfusion from dehydration, metabolic acidosis and increased serum lactate concentrations are noted on blood gas analysis. Due to enteric losses and a systemic inflammatory response, coagulopathy may be present.
In-hospital confirmation of canine parvovirus infection is achieved through the use of a SNAP test. These tests are easily performed and require a small sample of stool from the patient. These tests have been shown to detect the current CPV-2b and CPV-2c variants of the virus. Whether these tests show false positive results due to recent vaccine is a subject for debate. A recent study showed that these tests did not produce positive results as a result of vaccination with modified live Parvo vaccines, suggesting this test when positive indicated infection with wild type CPV-2.
When a patient is admitted to a hospital with confirmed or suspected parvovirus infection, precautions should be taken to prevent the spread of the virus to other patients. Precautions should include both personal protection as well as environmental decontamination. Personal protection is needed to prevent spread of the virus that may contaminate the caretaker and be transmitted to other patients. Personal protection should include clean disposable gloves, disposable long-sleeved gowns, and shoe covers. These items should not leave the isolation area. Any person handling the Parvo patient, items that come in contact with the Parvo patient, or samples from the Parvo patient, should ensure that they are performing proper hand decontamination at the completion of their tasks.
As important as personal protection is, isolation and environmental decontamination is even more important. The parvovirus has been shown to survive for long periods of time in the environment. Because of this, the hospital environment can be a reservoir for virus infection to naïve dogs. To minimize this risk, a well stocked separate ward or bank of cages in a low-use visible area of the hospital should be available for these contagious patients. Any supplies that are used should remain in this isolated area. Any medications for the patient can be brought into this isolated area at the beginning of any treatment or evaluation.
Environmental decontamination should include the isolated area, supplies in the isolated area, and any objects that come in contact with the patient or caretaker handling the patient. This may include stethoscopes, thermometers, and writing implements. Effective sanitation requires applying a germicidal agent to a basically clean surface. This requires use of both detergent and disinfectant products. Detergents in themselves do nothing to kill germs. Their purpose is to remove any organic matter prior to disinfection. Although some disinfectants can also act as detergents, many (such as bleach) do not. The majority of disinfectants used in veterinary hospitals are inactivated by organic material, so they are less effective when applied to surfaces that have not been thoroughly cleaned first. Periodically, a stronger degreaser should be used to remove body oils and other grunge that builds up on surfaces over time and can also inactivate disinfectants.