Feline Leukemia Virus and Feline Imunnodeficiency Virus FeL-V and FIV We recommend you carry out a FeL-V/ FIV test on your cat or kitten before it arrives. We only recommend testing through IDEXX as detailed below with their permission.
SNAP FIV/FeLV Combo Test Sensitivity and specificity of the SNAP® FIV/FeLV Combo Test
Sensitivity and specificity are based on visual interpretation of SNAP® test results. CL = confidence limit
Reference Method: 1. Petchek® FeLV Antigen Test 2. Petchek® FIV Antibody Test For retrovirus test interpretation and diagnostic algorithms, please refer to AAFP Feline Retrovirus Management guidelines, available at catvets.com/guidelines
The SNAP® Feline Triple® Test provides sensitive and specific detection of FeLV infection in cats
Study shows the Abaxis® VetScan® Feline FeLV/FIV Rapid Test and Zoetis Witness® FeLV-FIV Test demonstrate poor sensitivity for FeLV antigen.
Introduction Feline leukemia virus, or FeLV, is a highly contagious virus that is spread primarily via saliva among both domestic and feral cats in casual close contact—this can include sharing food and water as well as mutual grooming. FeLV infection can be a life-threatening condition— approximately one-third of cats that are infected with FeLV develop progressive infections and die of an FeLV-related disease within 3 years.1
The American Association of Feline Practitioners (AAFP) guidelines state that identification and segregation of infected cats is considered to be the single most effective method for the prevention of new FeLV infection.2
Infected cats are capable of transmitting the virus approximately 21–30 days postexposure. During this initial stage of infection, the concentration of FeLV antigen is low, twentyfold or more lower compared to later stages.3
Test sensitivity is a key factor during this stage because it allows identification of cats early in the course of infection and limits transmission of the virus. Poor test sensitivity could delay supportive care and result in transmission of the virus to casual-contact naïve cats. IDEXX Laboratories conducted a study to determine the sensitivity and specificity of three in-clinic diagnostic tests for FeLV antigen.
Study design Samples from 137 cats used in this study were random samples submitted by veterinary clinics to IDEXX Reference Laboratories and tested for the presence of FeLV antigen. 87 FeLV-positive samples and 50 FeLV-negative samples were identified using a PetChek® ELISA, which included both screening and confirmatory protocols.
The performance of the PetChek ELISA has been validated in several peer-reviewed studies.4–6 An immunoflourescence assay (IFA) was not used as a reference test in this study because it “yields a high number of false-negative and false-positive results…”1 The limitations of IFA in detecting FeLV have been well-documented.1,2,4,5
The samples were then tested using in-clinic tests following manufacturers’ protocols. The in-clinic tests evaluated in this study included IDEXX SNAP® Feline Triple® Test, Abaxis® VetScan® Feline FeLV/FIV Rapid Test and Zoetis Witness® FeLV-FIV Test. Test results were compared to the PetChek ELISA results for calculation of sensitivity and specificity.
The SNAP Feline Triple Test is highly sensitive and specific for detecting FeLV antigen in cats. • The Zoetis Witness FeLV-FIV Test was found to be less sensitive for FeLV antigen detection than the SNAP Feline Triple Test. Almost 1 in 5 positive samples would be missed on the Witness FeLV-FIV Test. • The Abaxis VetScan Feline FeLV/FIV Rapid Test was also found to be less sensitive for FeLV antigen detection than the SNAP Feline Triple Test. Almost 3 in 10 positive samples would be incorrectly called negative on the VetScan test.
These conclusions are consistent with those presented in an abstract at the 58th AAVLD/119th USAHA Annual Meeting, October 22–28, 2015.7
In this case, the superior sensitivity of the SNAP test is likely due to the bidirectional flow and signal amplification features of ELISA technology. These enhanced components of the SNAP assay are not present in the VetScan and Witness lateral flow tests.8 Optimal test sensitivity allows for early supportive care and helps to prevent transmission of the virus to naïve cats.
The SNAP® FIV/FeLV Combo Test screens cats for feline immunodeficiency virus (FIV) antibody and feline leukemia virus (FeLV) antigen.
What does a SNAP FIV/FeLV Combo Test result indicate?
To determine the test result, read the reaction spots in the result window. Any color development in the sample spots indicates the presence of FIV antibody or FeLV antigen in the sample. If no color develops in the positive control spot, repeat the test.
I ran the SNAP FIV/FeLV Test and received a light positive on a spot. Does the color intensity of the spot mean anything?
Any color development in any of the sample spots indicates a positive result.
Which types of samples can be used on the SNAP FIV/FeLV Combo Test?
Serum, plasma or anticoagulated whole blood (e.g., EDTA, heparin), either fresh or stored at 2–8°C for up to one week, can be used.
I used the incorrect conjugate/sample ratio. Can I rely on the results I received?
We recommend rerunning the test with the exact ratio of conjugate/sample listed in the package insert—3 drops of sample and 4 drops of conjugate.
What is the read time for the SNAP FIV/FeLV Combo Test and is it really important?
The test result must be read 10 minutes after the device is snapped. The test does not contain stop solution, and after 10 minutes, color development may occur that is not related to the sample. Do not report results read after 10 minutes.
How do the kit components need to be stored? • Store at 2–8°C until expiration date. • All components must be at room temperature (18–25°C) before running the test. Do not heat.
My SNAP FIV/FeLV Combo Test has been out of the foil package for the day. Can I still use it?
The SNAP FIV/FeLV Combo Test, and any other SNAP® test, must be used within two hours of removing it from the foil package.
Can my SNAPshot Dx® Analyzer read the SNAP FIV/FeLV Combo Test?
Yes, the SNAPshot Dx Analyzer can read the SNAP FIV/FeLV Combo Test.
Can the SNAP FIV/FeLV Combo Test be used with SNAP Pro® Mobile Device?
Yes, the SNAP FIV/FeLV Combo Test can be used with SNAP Pro Mobile Device
The Snap test Process
Initial testing/ Cattery admittance testing should be repeated after 30 days for FeL-V and 60 days for FIV after the initial test and annually for cats kept in long-term group housing.
Ask for the initial test result taken within 2 days of the kitten leaving to come home with you.
Isolate for at least 30 days before the retest for clearance.
Every single one of our kittens leave with a blood test to confirm negativity.