Performance of 4 Point-of-Care Screening Tests for Feline Leukemia Virus and Feline Immunodeficiency Virus

Background: More than 3 million cats in the United States are infected with FeLV or FIV. The cornerstone of control is identification and segregation of infected cats. Hypothesis/Objectives: To compare test performance with well-characterized clinical samples of currently available FeLV antigen/FIV antibody combination test kits. Animals: Surplus serum and plasma from diagnostic samples submitted by animal shelters, diagnostic laboratories, veterinary clinics, and cat research colonies. None of the cats had been vaccinated against FIV. The final sample set included 146 FeLV+, 154 FeLV-, 94 FIV+, and 97 FIV- samples. Methods: Prospective, blind comparison to a gold standard: Samples were evaluated in 4 different point-of-care tests by ELISA antigen plate tests (FeLV) and virus isolation (FIV) as the reference standards. All test results were visually read by 2 blinded observers. Results: Sensitivity and specificity, respectively, for FeLV were SNAP (R) (100%/100%), WITNESS (R) (89.0%/95.5%), Anigen (R) (91.8%/95.5%), and VetScan (R) (85.6%/85.7%). Sensitivity and specificity for FIV were SNAP (R) (97.9%/99.0%), WITNESS (R) (94.7%/100%), Anigen (R) (96.8%/99.0%), and VetScan (R) (91.5%/99.0%). Conclusions and Clinical Importance: The SNAP (R) test had the best performance for FeLV, but there were no significant differences for FIV. In typical cat populations with seroprevalence of 1-5%, a majority of positive results reported by most point-of-care test devices would be false-ositives. This could result in unnecessary segregation or even euthanasia.