FIV stands for Feline Immunodeficiency Virus. 

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In infected cats, feline immunodeficiency virus (FIV) attacks the immune system, leaving the cat vulnerable to other infections. Although cats infected with FIV may appear normal for years, they eventually suffer from this immune deficiency, which allows normally harmless bacteria, viruses, protozoa, and fungi found in the everyday environment to potentially cause severe illnesses. The median survival time for a cat diagnosed with FIV is approximately five years but many live much longer.

 

Most cats with FIV don't experience any significant FIV-health-related issues once they are fixed and living inside. The virus can affect their immune systems and make them more susceptible to kitty colds, and they are also prone to having dental issues, but most live long, relatively healthy lives. They don't need any special care or medication, just an indoor lifestyle and regular check-ups with a veterinarian. The thinking has also changed on how easily the virus can be transmitted to other cats -- it's primarily transmitted by deep bite wounds, so it's now believed that non-aggressive FIV+ cats can safely live with non-FIV cats. (Regular indoor-kitty wrestling and rough-housing that doesn't result in bites that break the skin will not transmit the virus.)

 

FeLV stands for Feline Leukemia Virus.  Feline leukemia virus (FeLV) is one of the most common infectious diseases in cats, affecting between 2 and 3% of all cats in the United States. Infection rates are significantly higher (up to 30%) in cats that are ill or otherwise at high risk (see below).

 

Fortunately, the prevalence of FeLV in cats has decreased significantly in the past 25 years since the development of an effective vaccine and accurate testing procedures.

Cats persistently infected with FeLV serve as sources of infection for other cats. The virus is shed in saliva, nasal secretions, urine, feces, and milk of infected cats. Cat-to-cat transfer of the virus may occur from a bite wound, during mutual grooming, and (rarely) through the shared use of litter boxes and feeding dishes. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing.

 

FeLV does not survive long outside a cat's body – probably less than a few hours under normal household conditions.

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Cats at greatest risk of FeLV infection are those that may be exposed to infected cats, either via prolonged close contact or through bite wounds. These include cats living with infected cats or with cats of unknown infection status, cats allowed outdoors unsupervised where they may be bitten by an infected cat, and kittens born to infected mothers.  Kittens are much more susceptible to FeLV infection than are adult cats, and therefore are at the greatest risk of infection if exposed. 

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During the early stages of infection, it is common for cats to exhibit no signs of disease at all. Over time, however,  an infected cat's health may progressively deteriorate or he/she may experience repeating cycles of illness and relative health. Signs can include:

• Loss of appetite

• Progressive weight loss

• Poor coat condition

• Enlarged lymph nodes

• Persistent fever

• Pale gums and other mucus membranes

• Inflammation of the gums (gingivitis) and mouth (stomatitis)

• Infections of the skin, urinary bladder, and upper respiratory tract

• Persistent diarrhea

• Seizures, behavior changes, and other neurological disorders

• A variety of eye conditions

• Abortion of kittens or other reproductive failures

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A relatively effective vaccine against FeLV is available, although it will not protect 100% of cats vaccinated, and it is not considered a core vaccine. Owners contemplating FeLV vaccination for their uninfected cats should consider the cats' risk of exposure to FeLV-infected cats and discuss the advantages and disadvantages of vaccination with a veterinarian. Since not all vaccinated cats will be protected by vaccination, preventing exposure remains important even for vaccinated pets. FeLV vaccines will not cause false positive FeLV results on ELISA, IFA, or any other available FeLV tests.

Although a diagnosis of FeLV can be emotionally devastating, it is important to realize that cats with FeLV can live normal lives for prolonged periods of time. While the median survival time for cats after FeLV is diagnosed is 2.5 years, cats with FeLV may also live for many years. They have no idea they're "sick" and are as happy and playful as any other cat until the signs manifest. They do succumb to issues secondary to the virus, but the good news is that they are generally happy and healthy until suddenly they aren't. They don't usually require any special care or medication, just lots of love. Because cats can transmit the virus through casual contact,  FeLV+ cats should be only cats, or live with other FeLV+ cats. The virus does not affect humans, dogs, or other animals.

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Thank you to both Erin Harty and the Cornell College of Veterinary Medicine for the information provided on this page.