More than 5 million cats across the U.S. are affected by feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), placing them at risk for disease and premature death.1 These are preventable, contagious retroviruses. Identifying and segregating infected cats is the key to controlling the spread of disease. As a result, positive cats are often euthanized based upon the results of a pet-side test.
Retroviral testing is “high stakes”
With retroviral testing, the stakes are high because the life of a pet faces imminent risk. Accurate results are paramount.
- A false-positive result means that a healthy, uninfected cat has tested positive. A positive test result could lead to that cat being euthanized unnecessarily.
- A false-negative result means that an infected cat has been missed and is considered free of the infection. If that cat is then placed in a household with other cats, it could endanger those cats.
New independent research conducted by Julie K. Levy, DVM, PhD, DACVIM, and her team at the Department of Small Animal Clinical Sciences at Maddie’s Shelter Medicine Program in Gainesville, Florida, identified significant differences in sensitivity and specificity provided by in-clinic tests from leading manufacturers.
Dr. Levy’s study determined that the IDEXX SNAP® FIV/FeLV Combo Test demonstrated higher sensitivity and specificity for FeLV than competing brands, including the Zoetis Witness® FeLV-FIV Test Kit and the Abaxis VetScan® FeLV/FIV Rapid Test, both of which are lateral flow tests. This means the IDEXX SNAP test had fewer false-positive and false-negative test results.1
FeLV test risks
The most significant findings of the Levy study pertained to FeLV. Both the Witness and VetScan Rapid lateral flow tests demonstrated relatively poor specificity for FeLV, which means they generated false-positive results for healthy, uninfected cats. The SNAP FIV/FeLV Combo Test generated zero false-positive results.
For instance, a test with 95% specificity falsely identified 5 out of 100 healthy cats as infected. This has increasing importance when screening for a disease that has a low prevalence in the population. In a situation like FeLV, where the prevalence in the tested population is 3%*, a test with low specificity can produce positive results that will more likely be wrong than right.
In “high-stakes” testing, accuracy could be life and death
Prevalence of FeLV is 3% in the population of tested cats.*
Based on the data from this independent, head-to-head study directly comparing in-clinic FeLV/FIV tests using the same sample set, the IDEXX SNAP FIV/FeLV Combo Test demonstrated superior performance in “high stakes” retroviral testing. And because in many cases, the test result is the diagnosis, using an accurate test where the result can be trusted is essential to providing quality medical care.
*IDEXX results from 1.9 million tests in the U.S. from 2013 to July 2016. Data on file at IDEXX Laboratories, Inc. Westbrook, Maine USA.
1. Levy J. Performance of point-of-care assays for FeLV and FIV [ACVIM Abstract ID06]. J Vet Intern Med. 2016;30(4):1475
posted by Melissa Beall, DVM, PhD
Dr. Beall received her veterinary degree from the Ohio State University College of Veterinary Medicine. She then worked in small animal practice and in laboratory animal medicine before entering a graduate program in Comparative Medicine at Cornell University. Over the last 14 years at IDEXX she has contributed to the development and launch of the vector-borne disease, pancreatic lipase and NT-proBNP diagnostic products. As a Medical Affairs veterinarian, she currently supports Rapid Assay products and Cardiopet proBNP at the Reference Laboratory.