Feline immunodeficiency virus (FIV) in cats

 

Chances are, if you’re reading this post about FIV in cats, you have a good reason.

 

Perhaps you’ve fallen in love with an FIV-positive cat at the shelter, and you want to know if this is a health problem you can deal with. Or maybe you just found out that one of your feline family members has tested positive for FIV and want to know how to handle it.

 

Most everything you need to know to move forward will be in this post. Keep reading.

 

But there is one thing I want cat lovers to know about FIV before I go any further: FIV is NOT an automatic death sentence. Years ago, cats were routinely “euthanized” for testing positive for this disease.

 

Today, we know better. A cat who is FIV-positive can be everything you ever wanted in a cat. And with a little extra attention, many FIV-positive cats can go on to live healthy, happy lives, and eventually pass from this world from something else entirely. You can give a cat the happy life she deserves in between.

 

What is FIV?

 

FIV is short for feline immunodeficiency virus. The name sounds a lot like HIV (which is short for human immunodeficiency virus) because it is similar. The difference, as you probably guessed, is that FIV only affects cats. Humans can’t get it; dogs can’t get it. Just cats.

 

FIV is a disease that attacks a cat’s immune system. It damages cells in the immune system, usually a kind of white blood cell called lymphocytes. Once this happens, it opens the door to all kinds of other nasty things that a healthy cat’s immune system would normally have no trouble fighting off: bacteria, viruses, protozoa, and fungi. A weakened immune system allows these other infections to run rampant.[1]

 

What is the history of FIV?

 

Feline immunodeficiency virus (FIV) was first discovered in a colony of rescue cats in the United States in the 1980s. These previously healthy cats started showing symptoms that were similar to those found in people with acquired immunodeficiency syndrome (AIDS).[2]

 

It is unfortunate that these two diseases were discovered at around the same time. HIV and AIDS were known to be so devastating in humans, that vets and shelters often put FIV-positive cats to sleep as a matter of course. [3]

 

We know more about FIV today, including the fact that FIV-positive cats deserve a chance to find a loving family. Unfortunately, many shelters still don’t have programs devoted to adopting out FIV-positive cats.

 

Estimates vary, but somewhere between 2.5% and 5% of otherwise healthy cats in the U.S. are infected with FIV.[4]

 

How does FIV work?

 

FIV is a kind of retrovirus, which only means that it’s a kind of virus that inserts RNA into a cell, instead of DNA. That’s not too important to know.

 

What is important, is that it’s actually a particular kind of retrovirus, called a lentivirus. Lentiviruses cause disease v-e-r-y slowly. This is critical when it comes to FIV. Because FIV is a lentivirus, chugging along at a snail’s pace, many FIV-positive cats live normal lifespans.

 

FIV does compromise a cat’s immune system, reducing his ability to fight off other illness. But FIV’s long latent period (more on this in a minute) and slow progression, means that the disease may never actually get around to seriously impacting a cat.[5]  Your cat may be FIV-positive, but you might not even notice.

 

How do cats get FIV?

 

A cat who has FIV will have FIV in his saliva. If this FIV-positive cat bites a healthy cat, his saliva can get into the wound and infect the bitten cat.

 

This is what it usually takes to transmit FIV: a severe, deep, puncturing bite.

 

(Ever been bitten yourself? Read this post, "What to do if a cat bites or scratches you.")

 

Can cats get FIV from friendly contact? Can FIV-positive cats live with other cats?

 

Usually.

 

Why do I say, “usually”? It is unlikely, but theoretically possible, that FIV could be spread by friendly contact between cats, such as mutual grooming.[6] But in fact, this kind of transmission has only been demonstrated in laboratory conditions – not in real life. In order for a healthy cat to catch FIV in this way, up to 10,000 times more virus is required than might be delivered by a bite.[7] It’s just not likely.

 

The first long-term study on this topic was conducted by Dr. Annette Litster at Purdue University College of Veterinary medicine. It was a five-year study that followed 89 pairs of FIV-negative and FIV-positive cats. It proved that FIV-positive and FIV-negative cats can live together without the risk of transmitting the disease.[8]

 

For negative and positive cats to live together, they must get along. Fighting can lead to bite wounds, which can lead to transmission of the virus.

 

But cats who live peaceably together can continue to do so.

 

Can cats get FIV from sharing food bowls and litter boxes?

 

It’s also theoretically possible that FIV could be transmitted by sharing food bowls and litter boxes.

 

Fortunately, however, FIV doesn’t survive long in the environment. It’s very fragile. Everything kills it: light, air, heat, and household disinfectants.[9]

 

Most importantly, there is no proof that a single cat has ever contracted FIV from shared bowls and boxes.

 

Can cats get FIV from a blood transfusion?

 

Cats could theoretically get FIV from a blood transfusion. But it would take an extremely irresponsible veterinarian to use an FIV-positive cat to give blood to a cat without FIV.

 

Can kittens get FIV from their mothers?

 

FIV-positive pregnant mommas can pass the disease on to their kittens during pregnancy, birth, or during nursing, but it is not as common a problem as previously thought.

 

The problem is that kittens who are born to FIV-positive mothers can actually inherit FIV antibodies, but not have the disease itself. Tests for FIV typically test for the antibodies, so a kitten who does not have FIV could have a false-positive test.[10]

 

Kittens who test positive for FIV need to be retested between the age of six and eight months, when the antibodies have begun to wane. At this age, most kittens finally test negative for FIV.

 

Can cats get FIV from parasites that suck blood?

 

Currently, we don’t know if parasites that suck blood, such as fleas, can spread the disease. But this possibility is just one more reason to stick to a strict flea-control program.[11] As if you needed another reason, right?

 

(Read, "My cat has fleas! What should I do?")

 

Can a cat get FIV from a positive cat with an open wound?

 

No. FIV is not transmitted through open wounds.

 

What kinds of cats get FIV?

 

Any cat can get FIV under the wrong circumstances.

 

But the cats most likely to have FIV are adult male cats who have not been neutered, and who are given free roam of the outdoors, or some kind of outdoor access.[12]

 

Why?

 

Intact male cats who roam are more likely to get into fights, and thus receive a serious bite from an FIV-positive challenger in a fight.[13]

 

Can humans, dogs, or other pets in the house catch FIV?

 

No. FIV is species-specific. This means that you cannot get FIV from your cat. Your kids cannot get FIV from your cat. Your dogs, guinea pigs, birds, hamsters, or any other household pet you have cannot get FIV from your cat.

 

How are cats tested for FIV?

 

There’s a simple blood test that most shelters and veterinarians can perform on site. It’s called an IDEXX SNAP test. It looks for antibodies to FIV. It’s quite accurate, but there are times when it can produce a false positive, meaning that a cat who does not actually have the disease tests positive for the disease.

 

Kittens who have inherited antibodies from their FIV-positive mothers could test positive, but not actually have FIV. Kittens need to be retested at between six and eight months of age.

 

Cats who were given an FIV vaccine at some point in their lives could test positive, even if they don’t have FIV, because the vaccine itself causes a cat’s body to produce antibodies.

 

A cat who tests positive should be retested using a PCR test, also called an antigen test, such as IDEXX FIV RealPCR test, to confirm the positive result. A PCR test looks for the actual virus, not just the antibodies to the virus. [14]

 

Cats can also test false-negative on the antibody test, by the way. Because it takes time for antibodies to develop, a cat who was just infected might not have antibodies in his blood yet. If you think your cat was exposed to FIV, wait 60 days and test again for a more accurate result.[15]

 

Cats who are in the end stages of FIV may also test false-negative. If a cat’s immune system is so compromised by disease, it may not be able to produce enough antibodies to be detected by the test.[16]

 

Is there a vaccine for FIV?

 

Yes, there is a vaccine, and no there is not, depending upon where you and your cat live.

 

A vaccine was developed, but as of 2016 it is no longer available in the United States. The vaccine is still available in other countries, including Australia, New Zealand, Japan.[17]

 

The reason the vaccine is no longer available in the U.S. is twofold: first, it did not work on all of the strains of the virus.

 

Second, screening for FIV can’t tell the difference between a vaccinated cat and one who actually has the virus. If a vaccinated cat got lost and ended up at the wrong shelter, she could end up losing her life. Many shelters in the U.S. still routinely “euthanize” FIV cats, claiming they are unadoptable.[18]

 

What are the symptoms of FIV in cats?

 

This disease typically progresses through three different phases:

 

The acute phase

The acute phase begins one to three months after infection. The virus is carried to the lymph nodes where it begins to reproduce in a certain kind of white blood cell called T-lymphocytes. Cats in the acute phase often have a fever, seem depressed, and lose their appetite. This phase is often missed by guardians, or they attribute the symptoms to another cause. [19]

 

(Read, "How do you know if your cat is sick?")

 

The asymptomatic (or latent) phase

“Asymptomatic” means that the cat has no outward signs of any disease, and the asymptomatic phase can last for months or even years. During this phase, the virus makes copies of itself very slowly. If bloodwork is performed on a cat in this phase, it might show low-white-blood-cell counts, or increased proteins.

 

Some cats stay at this stage for the rest of their lives.[20]

 

The progressive phase
As the virus continues to spread through the immune system, a cat can become immunocompromised.

 

This means that other infections can take hold. In fact, most of the illness that a cat experiences during an FIV infection is not directly from FIV.

 

Cats can develop chronic infections of the skin, eyes, urinary tract, and upper respiratory tract. Gums can become inflamed and some FIV-positive cats develop severe dental disease.

 

Cats in this phase are more likely to develop cancer and blood disorders than healthy cats. Some begin to lose weight, have seizures, develop neurological disorders, or show behavioral changes.[21]

 

These are some of the symptoms that cats in the progressive phase of FIV can develop:

 

• Poor coat condition
• Fever
• Lack of appetite
• Inflammation in the mouth and gums
• Infections in eyes, skin, upper respiratory, bladder
• Constant diarrhea
• Vomiting
• Chronic conjunctivitis of the eyes
• Swollen lymph nodes
• Seizures
• Behavioral changes[22][23]

 

How do you care for an FIV-positive cat?

 

Having an FIV-positive cat in your life does not require any special medication or treatment. Your only job is helping your cat live as healthy and stress-free as possible.[24]

 

Start by spaying or neutering your cat and keeping him or her indoors. A spayed female cat cannot pass FIV on to kittens, and a neutered male cat is less likely to fight. Keeping FIV-positive cats indoors will prevent them from spreading the disease to other cats.

 

FIV-positive cats should live alone or with other non-aggressive cats. Stress can suppress an already-weakened immune system.[25]

 

Feed your cat a high-quality diet – the best cat food you can afford. Don’t feed any raw food: not raw meat nor raw eggs, and no unpasteurized dairy products. You want to avoid the risk of food-borne bacteria and parasites, which can challenge a cat’s already-compromised immune system.

 

Visit your vet every six months or so. Your vet will pay extra attention to “trouble spots” for FIV-positive cats, like gums, skin, eyes, and lymph nodes. Your cat’s weight will be measured and recorded, to make sure that he’s not losing too much. Your vet can perform a blood test and urinalysis every year.[26]

 

By keeping a close eye on your cat’s health with frequent vet visits, your cat can be treated promptly when symptoms arise. Remember, most illnesses in FIV-positive cats are the result of secondary infections, not FIV itself.

 

Note that once a cat has experienced one or more severe illnesses as a result of FIV infection, such as a fever that won’t go away or severe weight loss, the long-term prognosis for the cat is not as favorable.[27]

 

Are there any treatments for FIV?

 

Drugs developed for human immunodeficiency virus, HIV, are sometimes used in cats. These include zidovudine, also known as Retrovir (AZT), which may help cats with severe dental inflammation (stomatitis) or neurologic disease.

 

One study summarized the effectiveness of about 23 different human drugs for use in cats with FIV. It found that most of them were not very helpful in extending life, and most had serious side effects.[28]

 

There is ongoing research into antiviral therapies.[29]

 

Is FIV fatal?

 

The most common cause of death in FIV-positive cats is old age. FIV-positive cats may never show any symptoms and many go on to live long happy lives.

 

The worst complications are usually in cats who have been living outdoors and fending for themselves, or had other diseases or poor health to begin with.[30]

 

Is there a cure for FIV in cats?

 

No. There is no cure for FIV in cats.

 

As a matter of fact, there aren’t cures for any of the thousands of viruses that cats and humans get.

 

How can I prevent my cat from getting FIV?

 

The only way to prevent your cat from getting FIV is to keep her indoors and away from infected cats who are likely to bite your healthy cat.

 

Do cats ever “get over” FIV?

 

As far as we know, once a cat is infected, he will remain infected for the rest of his life.[31]

 

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Dawn LaFontaine

Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.

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FOOTNOTES

 

[1] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine, 17 June 2021, https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-immunodeficiency-virus-fiv.

 

[2] Care, International Cat. International Cat Care, 6 Oct. 2019, https://icatcare.org/advice/feline-immunodeficiency-virus-fiv/.

 

[3] “Facts about FIV-Positive Cats • Seattle Area Feline Rescue.” Seattle Area Feline Rescue, 7 July 2020, https://www.seattleareafelinerescue.org/fiv-positive-cats/.

 

[4] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine.

 

[5] “What Is FIV?” FIV Cat Rescue, 5 Mar. 2020.

 

[6] Care, International Cat. International Cat Care.

 

[7] “Update on FIV.” Maddie's Fund, https://www.maddiesfund.org/update-on-fiv.htm.

 

[8] AL;, Litster. “Transmission of Feline Immunodeficiency Virus (FIV) among Cohabiting Cats in Two Cat Rescue Shelters.” Veterinary Journal (London, England : 1997), U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/24698667/.

 

[9] “What Is FIV?” FIV Cat Rescue.

 

[10] ibid.

 

[11] Care, International Cat. International Cat Care, 6 Oct. 2019,

 

[12] “Update on FIV.” Maddie's Fund.

 

[13] “Facts about FIV-Positive Cats • Seattle Area Feline Rescue.”.

 

[14] “What Is FIV?” FIV Cat Rescue.

 

[15] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine.

 

[16] ibid.

 

[17] ibid.

 

[18] “What Is FIV?” FIV Cat Rescue.

 

[19] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine.

 

iibid. 

 

ibid.

 

[22] Contributors, WebMD Editorial. “FIV and Cats: Symptoms, Causes, and Treatments.” WebMD, WebMD, https://pets.webmd.com/cats/cat-fiv-feline-immunodeficiency-virus. 

 

 

[23] ibid.

 

[24] “Facts about FIV-Positive Cats • Seattle Area Feline Rescue.”.

 

[25] Buffington CAT, Bain M. Stress and Feline Health. Vet Clin North Am Small Anim Pract. 2020 Jul;50(4):653-662. doi: 10.1016/j.cvsm.2020.03.001. Epub 2020 Apr 27. PMID: 32354488; PMCID: PMC8801065. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8801065/.

 

[26] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine.

 

[27] ibid.

 

[28] Hartmann, Katrin, et al. “Efficacy of Antiviral Drugs against Feline Immunodeficiency Virus.” Veterinary Sciences, MDPI, 18 Dec. 2015, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644647/.

 

[29] “Feline Immunodeficiency Virus (FIV).” Cornell University College of Veterinary Medicine.

 

 

[30] “Facts about FIV-Positive Cats • Seattle Area Feline Rescue.”.

 

[31] Contributors, WebMD Editorial. “FIV and Cats: Symptoms, Causes, and Treatments.”.