- FIV and FeLV are different types of retrovirus. FeLV is a gammaretrovirus and FIV is a lentivirus.
- FIV is primarily transmitted through biting from infected cats. Casual contact between cats is VERY unlikely to cause transmission.
- FeLV can be transmitted through saliva, tears, nasal secretions, urine, and feces.
- Cats who test positive for FIV and those who test negative can live together without transmission if the cats do not fight.
- Cats with FeLV should live with other FeLV-positive cats or cats vaccinated against FeLV (however, keep in mind that the FeLV vaccine is not 100 percent effective)
- FeLV-positive cats are at high risk of developing cancers
- Cats who contract FeLV can fight off the virus and develop future immunity. This is known as abortive infection.
- FeLV has a vaccine in use. FIV also has a vaccine but it was discontinued in the U.S. and Canada in 2015.
Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) are feline-only retroviruses that cannot be transmitted to humans or other animals. Not all cats who test positive for FIV or FeLV will develop infections or symptoms that are fatal or that otherwise seriously impact their quality of life.
Though they have weaker immune systems, cats who test positive for FIV or FeLV can live fulfilling and happy lives like any other cats—and can live for many years.
That is why Alley Cat Allies recommends against testing community cats for these retroviruses during Trap-Neuter-Return (TNR). To help as many animals as possible, resources should be used to increase TNR efforts or provide other care to adoptable cats.
A growing number of animal shelters, veterinary professionals, and animal organizations, including the American Association of Feline Practitioners (AAFP), have joined Alley Cat Allies in establishing protocols to no longer test all cats, particularly community cats, for FIV and FeLV. They are recognizing that indiscriminate testing is unreliable, wasteful, and could be a death sentence for cats who could live for many years.
When should a cat or kitten be tested for FIV or FeLV?
A shelter or community cat or kitten should only be tested if she is showing signs and symptoms of illness that may be related to a compromised immune system caused by FIV and FeLV. If cats are not ill, we do not recommend testing. For shelters, we recommend advising adopters to have their new cat or kitten tested at a veterinarian rather than testing in-house prior to adoption.
Kittens under 6 months of age should not be tested, as they may test positive for FeLV or FIV even though they are rarely infected. The antibodies of these retroviruses can be passed from infected mothers through nursing and will pass through the kitten in time. Kittens should only be tested if they are above 8 months of age.
Why NOT to Test for FIV or FeLV
Alley Cat Allies, informed by the advice of our veterinary experts, has long advocated against routinely testing community cats for FIV and FeLV for these reasons:
- Rate of infection is low. One study detected FeLV in only 4.3 percent of community cats and FIV in 3.5 percent of community cats, which are similar to the rates in owned cats. Several large-scale TNR programs reported a 1-2 percent incidence of FeLV.
- Tests, including the IDEXX SNAP FIV/FeLV Combo Test, are not 100% accurate. It can take 30 days or more after initial exposure for infected cats to test positive for FeLV and up to 60 days for cats infected with FIV. Cats can also test positive for FeLV at first but end up fighting off the virus, which means they become FeLV-free and will test negative later. In short, the circumstances and timing of FIV and FeLV testing have to be ideal, or cats will need retesting for full accuracy. This is not a viable option for community cats, who are not socialized and live outdoors.
- Vaccines often cause positive test results. FIV tests do not differentiate between FIV infection and FIV vaccination, which can cause false positive test results. In too many circumstances, those false positives lead to the “euthanasia” of vaccinated cats who are not infected.
- TNR protects more cats than FIV/FeLV tests. Because FIV and FeLV can spread through mating or bite wounds caused by fighting, spaying or neutering cats is the best way to inhibit transmission of the viruses. When cats are spayed or neutered, mating-related behaviors like fighting stop. Cats also can no longer get pregnant, so they can’t transmit the viruses to their kittens.
- FeLV and FIV tests are expensive. The cost of testing can hinder the success of important programs like TNR. Rather than wasting valuable resources on testing community cats for FIV and FeLV, those funds need to be utilized for community cat spay and neuter efforts in order to save the most cats.
- Cats who test positive for FIV or FeLV can have a high quality of life like any other cat. Infected cats are often asymptomatic, meaning they can remain healthy with no signs of illness for many years—even for their entire lives. Cats who test positive for FIV and FeLV are often killed in shelters before they even show any symptoms or develop any infections that impact their health. These cats are robbed of what could be a happy and fulfilling life.
Alley Cat Allies does not support the killing of FIV- or FeLV-positive cats who are asymptomatic or have manageable infections that do not severely impact their quality of life.
The American Association of Feline Practitioners also recommends against routine “euthanasia” of healthy FeLV- and FIV-positive cats. Euthanasia should only be used to relieve suffering from a terminal or incurable condition. Cats showing signs of illness or injury should be taken to a veterinarian for medical treatment. Learn more about the difference between euthanasia and killing.
 Schumacher, Erica, “Why are some shelters no longer testing all cats for FeLV and FIV?” University of Wisconsin-Madison School of Veterinary Medicine (2019): https://www.uwsheltermedicine.com/library/resources/why-are-some-shelters-no-longer-testing-all-cats-for-felv-and-fiv