Feline immunodeficiency virus (FIV) in cats

Feline immunodeficiency virus (FIV) is a viral infection that affects cats’ immune systems, leaving them vulnerable to secondary infections and illnesses. Although FIV is rare in the UK, it is essential for cat owners to understand the virus, particularly if they own multiple cats or care for strays. This guide provides up-to-date information on how FIV is transmitted, diagnosed, managed, and what you can expect when adopting or caring for an FIV-positive cat.

What is Feline Immunodeficiency Virus (FIV)?

Feline immunodeficiency virus, commonly called FIV, is a virus that only affects cats. Much like the human immunodeficiency virus (HIV) affects humans, FIV weakens a cat’s immune system, making it harder for the body to fight off infections. However, FIV is species-specific and cannot be passed to humans or other animals. 

FIV has been compared to feline leukaemia virus (FeLV) because both viruses suppress the immune system and can lead to similar health issues. However, FIV progresses more slowly than FeLV, and many cats with FIV can live relatively long, healthy lives with proper care.

How does FIV spread?

FIV is found in a cat's saliva and blood and is mainly transmitted through bite wounds. Because of this, male cats, especially those that are unneutered, are at higher risk as they tend to fight over territory and mates. Transmission is less common among indoor cats that do not have access to other cats or aggressive situations. 

While it’s less common, FIV can also spread from a mother cat to her kittens during pregnancy or through nursing. However, maternal transmission is rare, and most infected kittens are born to mothers who became infected during their pregnancy.

Recognising the signs of FIV in cats

Many cats infected with FIV do not show symptoms immediately. The virus can stay dormant in their bodies for years, slowly weakening the immune system. Cats with FIV can appear healthy for a long time before symptoms appear. When symptoms do develop, they may include:

• Recurring fevers  
• Swollen lymph nodes  
• Loss of appetite and weight loss  
• Dental issues, such as gingivitis or stomatitis  
• Skin, eye, and upper respiratory infections  
• Chronic diarrhoea  

As FIV progresses, infected cats may experience various secondary infections and health issues due to their weakened immune systems. The symptoms often resemble those of other common illnesses, so FIV can be challenging to diagnose without a blood test.

Diagnosing FIV in cats

FIV is diagnosed through a blood test that detects antibodies produced in response to the virus. However, because antibodies can take weeks to form, testing immediately after a possible exposure may not provide an accurate result. In cases where FIV infection is suspected, your vet may recommend multiple tests over a period of several weeks.

In kittens born to FIV-positive mothers, antibodies may be present in the kitten’s blood due to the mother’s immune response. This does not mean the kitten is necessarily infected. In these cases, the kitten should be retested after six months to confirm their status.

Health conditions associated with FIV

Due to their weakened immune systems, cats with FIV are more susceptible to infections and other health issues. Common conditions associated with FIV include:

• Anaemia: FIV-positive cats may suffer from anaemia, a condition that reduces the number of red blood cells, leading to lethargy and fatigue.
• Chronic inflammatory conditions: FIV-positive cats often develop chronic inflammation, which can affect the eyes, joints, or other organs.
• Kidney disease: Kidney issues are common in FIV-positive cats as their bodies struggle to fight infections.
• Tumour diseases: FIV-positive cats may be at higher risk of certain cancers due to immune suppression.

Early detection and treatment of these conditions can significantly improve the quality of life for an FIV-positive cat.

Managing FIV: medication, diet, and lifestyle

While there is no cure for FIV, supportive care is essential to help FIV-positive cats live comfortably. This care typically involves:

• Regular veterinary check-ups

Routine vet visits help catch secondary infections early and monitor the cat’s overall health. Common treatments include antibiotics for bacterial infections and antiviral medications to manage symptoms.

• Diet recommendations

A balanced diet is crucial for an FIV-positive cat’s immune system. High-quality commercial cat food is recommended, as raw diets may expose cats to bacteria that their weakened immune systems cannot handle. Discuss dietary needs with your vet, as they may suggest supplements to boost your cat’s immunity.

• Home environment

FIV-positive cats do best in a stable, stress-free environment. Limiting interactions with unknown cats can reduce the risk of additional infections. Cats with FIV are also more vulnerable to parasites, so regular flea and worm treatments are essential.

Adopting an FIV-positive cat

Adopting an FIV-positive cat can be incredibly rewarding. These cats are just as affectionate and playful as other cats, and with the right care, they can enjoy long, happy lives. Before adopting, consider your ability to provide a low-stress, stable environment and to cover regular veterinary visits. FIV-positive cats may require more frequent check-ups and preventive care than other cats.

Can FIV-positive and FIV-negative cats live together?

In many cases, FIV-positive and FIV-negative cats can live together peacefully. Since FIV is mainly transmitted through bites, cats that get along well have a low risk of transmission. However, always discuss the risks with your vet before introducing an FIV-positive cat to a new household.

Should FIV-positive cats go outdoors?

Allowing an FIV-positive cat outdoors poses risks, as they can catch secondary infections and may spread the virus to other cats through bites. For FIV-positive cats, an enclosed outdoor space like a secure garden or catio offers a good compromise. This gives them the freedom to enjoy fresh air and sunshine without exposing them to other cats or dangers.

FAQs about Feline Immunodeficiency Virus (FIV)