Parvovirus is a potentially deadly disease that, unfortunately, is also fairly common

Most veterinarians have diagnosed and treated their fair share of parvovirus. While most common by far in young puppies, the disease can also occur in adult dogs on occasion, especially those who are unvaccinated. 

Due to parvovirus’ ability to cause severe illness and death (even with treatment), many veterinarians use point of care tests for the virus in their practice. This can help provide an answer and aid in forming a treatment plan right away, along with a plan to isolate the affected dog to limit spread of the highly contagious virus. Also, having a tangible result to show clients may help with challenging conversations about the seriousness of the condition and the expense of treatment.

At the same time, it’s important to understand the limitations of the test and to choose the brand that best fits the needs of an individual practice. Here are some things to consider…

Which Tests are Available for Parvo Testing in Dogs?

Tests are available for in-house. Laboratory testing is also available, including PCR testing that may be helpful especially for follow-up on a suspected false-negative result.

For point of care tests, here are two popular options for veterinary practices…

• IDEXX SNAP Parvo Test

IDEXX claims to have high accuracy, with reference laboratory quality technology and 100% sensitivity and specificity as stated in the company’s supplemental materials on the test. They also claim to not cross-react (have a false positive test) following administration of modified live parvovirus vaccines. Results are ready in 8 minutes, and the test can be stored at room temperature. A SNAP Pro Analyzer is available to automatically activate and read tests, and add results to the medical record.

• Zoetis WITNESS Parvo Rapid Test

Zoetis states the WITNESS test is easy to use, without the need to snap the test. Some vets report it is more affordable, too. It has a reported sensitivity of 86.3% and specificity of 96.1%. The test offers results in 10 minutes, room temperature storage, and an extended (12-month) shelf life. 

Zoetis also offers the VETSCAN Parvo Rapid Test, which they report has a sensitivity of 96.0% and specificity of 98.7%. VETSCAN results take 10-15 minutes.

Considerations for In-House Parvo Testing

These tests look for parvovirus antigen (viral shedding) in canine feces. With this in mind, it’s important to consider everything that could affect a test’s accuracy.

For example, false negatives are possible—so a negative result doesn’t completely rule out a parvo infection in a symptomatic dog. This is because fecal shedding of parvovirus only occurs in a specific time window following exposure, and thus a puppy may have been outside this window when tested. Follow-up laboratory testing may be of value here, and treatment may need to be initiated in a clinically ill dog.

Anecdotal reports of false positives also occur following vaccination with a modified live parvovirus vaccine. It’s worth noting that IDEXX’s study on post-vaccinal false positives only included 64 dogs, so perhaps the occasional false positive would be seen with a much larger study population. In general, a false positive is more likely to be a “weak” positive rather than a strong one, and this most commonly occurs 4-14 days after vaccination. 

For both suspected false positives and suspected false negatives, it’s important to look at the entire clinical picture. Does the puppy have any vomiting, diarrhea, lethargy, fever, that characteristic “parvo smell,” or any other clinical signs? Is their CBC or blood smear normal, or is neutropenia or any other abnormality present? How old are they, and what’s their vaccination history? It’s often also worth running a fecal test or treating empirically for worms in puppies with GI symptoms.

Testing for Feline Panleukopenia Virus in Cats Using a Parvo Test

Veterinarians have reported using point of care parvovirus tests to test for panleukopenia virus in cats, with a good degree of accuracy. It’s worth noting that this is considered off-label and not necessarily endorsed by the manufacturers. A veterinarian must use their clinical judgment to decide if this is something that might be beneficial to feline patients with possible panleukopenia virus. Similar to testing for parvovirus, false negatives can occur, and false positives can follow a recent vaccination.

Purchasing Considerations

Be sure to consider brand preference (if special deals are available when purchasing other equipment or tests from the same company), contracts, quantity sold, expiration dates, availability of technical support, and any other factors that could be relevant to using the tests in clinical practice.

Details and specifics of these tests may evolve over time. It’s important to check directly with the company for the most up-to-date information before making a purchase.

Written by: Dr. Tammy Powell, DVM

Disclaimer: This article is for general informational purposes only, and not intended as a guide to the medical treatment of any specific animal.