Feline Leukemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) are two of the most devastating contagious viruses seen in cats. Both viruses compromise the immune system causing poor health, frequent infections, blood disorders and cancer at any age.

What is FeLV?

Feline Leukemia Virus is a highly contagious virus that replicates within the body with the long term goal of infecting the bone marrow. Once in the bone marrow FeLV causes blood disorders such as anemia, weakens the immune system and ultimately cancers such as leukemia/lymphoma. If a cat’s immune system is healthy or is vaccinated they can clear this virus with no long term effects.

What is FIV?

Feline Immunodeficiency Virus is akin to the Human Immunodeficiency virus (HIV) which leads to AIDS. FIV cannot be transmitted to humans but it does cause a very similar course of disease where the FIV virus will be dormant with no signs of infection before breaking into fulminant disease. The terminal phase of FIV causes severe suppression of the immune system, blood disorders, and cancer.

How does a cat contract FIV or FeLV?

FIV is transmitted through bites from infected cats. It can also be given to kittens from their mother if she has the virus especially if she is actively ill from the virus at the time of birth.

FeLV is transmitted through saliva of infected cats most commonly through mutual grooming, shared food/water bowls, from an infected mother to her kittens and through biting.

How is a cat diagnosed with FIV or FeLV?

FeLV is diagnosed most commonly with a bed side test detecting antigen which is the actual virus particle itself. When positive a cat truly has FeLV.

FIV is much more difficult to test for as there are not antigen based tests available. The tests available while easy to run detect antibody which is the body’s response to the virus. It is true that when a cat becomes exposed to FIV they cannot clear it and will show up antibody positive. However, if a cat was vaccinated with the FIV vaccine they will also show up positive. Due to this a positive FIV test is interpreted relative to a cat’s medical history.

How to protect a cat from these viruses

Keeping a cat indoors is the easiest way to prevent contracting either virus as the most likely source is from feral or unvaccinated cats often through fighting & bites.

There is a very effective vaccine for FeLV that should be given on an annual basis in adult cats that spend any time outdoors or around another FeLV positive cat.

There is a FIV vaccine available, however it is nowhere near as effective as the FeLV vaccine. Compared to a Rabies vaccine which has usually somewhere around 99% efficacy FIV vaccines have been documented as low as 74% effective. Due to this most practitioners do not recommend vaccinating for FIV especially as it interferes with testing. Vaccinating may be considered in very high risk cats and on a case by case basis.

How often should a cat be tested for these Viruses?

Any cat that is outside on a regular basis should be tested yearly as they have the highest exposure and risk to contract these viruses. Cats that have been treated for bite wounds from other cats should also be tested no sooner than 6 weeks after contracting a bite. This test should also be performed on kittens prior to adoption. If a cat is kept indoors and has no exposure one test verifying negative status for both viruses is sufficient.

If you ever have questions – Do not hesitate to as a UVHvets Vet!

We are always here for you and your pet questions. We thrive on client education!

Enjoy the week – Dr. Rachel McNair