Feline Leukaemia Virus (FeLV): Symptoms, Treatment & Prevention

Leukaemia in any species is a cancer that affects the tissues that produce blood. This is mainly the bone marrow and the lymphatic system. In cats, as in other animals, leukaemia can occur spontaneously like any cancer but by far the most common cause of leukaemia in cats is a viral infection. It’s this virus, Feline Leukaemia Virus (FeLV) that we’ll be talking about in this article. FeLV does cause the cancer leukaemia in cats but it can also affect cats in other ways, as we’ll see. Not all cats with FeLV will develop cancer and not all cats with leukaemia have FeLV.

Although cat leukaemia caused by FeLV can be a difficult condition to manage, pets with it can still live relatively happy, albeit shortened lives. Understanding feline leukaemia symptoms can help you better care for a cat with this disease. Additionally, by being familiar with FeLV itself, you may be able to detect it sooner or prevent it altogether.

What is feline leukaemia?

According to  a pan-european study, FeLV affects between 1% and 9% of  healthy cats in Europe. It's a contagious viral disease that's spread between cats, mostly through saliva and/or blood contact. FeLV can also be spread through urine and faeces, and from a mother cat to her kitten in utero (in the womb) or through the mother's milk.

While FeLV can be contracted through fighting, it's better known as a "loving disease" — cats can spread it by rubbing noses and grooming each other. A cat with FeLV can still spread the disease if they appear perfectly healthy.

FeLV is one of the leading causes of death among cats. Fortunately, the incidence of FeLV has decreased significantly thanks to early detection, broader awareness of the signs and effective vaccines.

What are the symptoms of FeLV?

FeLV infections can be tricky for two main reasons: the virus attacks many systems in the body, and the signs vary depending on which system is affected. It is one of the most common causes of cancer in cats and can cause blood disorders. Feline leukaemia weakens the immune system of an affected cat, leaving them susceptible to secondary infections.

A cat who's been recently infected may not show signs at all; however, over time, their health will slowly decline due to repeated infections, due to their weak immune system and/or cancer. Cats with feline leukaemia virus may demonstrate:

• Weight loss
• Poor appetite
• Unkempt fur or poor hair coat
• Persistent or recurrent fevers
• Swollen lymph nodes
• Pale or inflamed gums
• Eye problems
• Seizures
• Chronic diarrhea or runny stools

Recurrent infections of the skin, bladder, nose and/or eyes are also common signs of cat leukaemia.

How is feline leukaemia diagnosed?

If your veterinarian suspects your cat has FeLV, they can be screened through a simple  ‘snap’ blood test. If your veterinarian uses a reference laboratory, snap test results can be available within 24 hours. In some instances, this test can also be performed in the clinic while you wait.

The snap test detects the virus in the blood; however, it is not 100 percent accurate. If a cat tests positive for FeLV, another blood sample must be sent to the lab to confirm infection through an IFA test (immunofluorescent antibody assay: a scientific test to look for specific antibodies that are present with FeLV). In some cases, a PCR (polymerase chain reaction) blood test is run as well. Your vet will be the best resource on which test is right for your cat.

What if my cat tests positive for FeLV?

First thing's first: Do not panic. One positive test result doesn't necessarily mean your cat has FeLV. According to International Cat Care, occasional false results do occur. If your cat or kitten tests positive, one of the more accurate laboratory tests that we mentioned before, will be run. Cats testing positive on both should be isolated from other cats and retested in 12-16 weeks. Sometimes cats test positive because they have recently been exposed but then fight the virus off. Retesting may show them to be negative.

Based on the combined result of these tests, your vet will be able to make the most accurate recommendation regarding what to do next.

What is the treatment for feline leukaemia?

There is no definitive cure for FeLV. Sadly, most cats with the disease die within 2 to 4 years, but with good management and veterinary care, this time can still be a good quality of life.  Your cat’s care and prognosis will be affected by what exactly the virus causes for your individual cat at any given time. The three main ways your cat could be affected are anaemia, a weakened immune system and cancer. Bear in mind that your cat could have one, two or all three of these at the same time.

• Anaemia. Although any cause of leukaemia affects mainly white bloods cells, red cell production can also be affected. If your cat has anaemia, they may require blood replacement products or transfusions, if that is an option where you live.
• Weakened immune system. Due to low white cell levels your cat will be prone to succumbing to infections that they would normally, easily fight off. In these cases your vet may need to give antibiotics or other medications, depending on what infection your cat has. You may need to be very careful about possible routes of infection into the house, like visitors etc.
• Cancer. If your cat does develop the cancer leukaemia, the outlook is more guarded. Your vet will advise what, if anything, you can do if that situation arises.

Because of all the ways your cat might be affected by FeLV, it's important that your cat stays under the close supervision of a vet who can promptly head off any problems, such as complications from secondary infections, to ensure they stay as healthy as possible. Twice yearly vet examinations are recommended, which may include annual or biannual blood or urine tests.

As FeLV can be easily spread to other cats, it's crucial that pets who are infected stay strictly indoors, ideally in a home where they're the only cat. Cats with FeLV may be more affected by stressful environments, because stress also weakens the immune system. Providing indoor enrichment, such as adding toys or new elements to their play space, can help reduce stress. Also, consider having a vet come to your home to suggest ways you can make the space more soothing for a cat with FeLV.

Raw food is never ideal for animals for many reasons but because they have a weakened immune system, cats with FeLV should definitely not be fed raw food, but instead a complete and balanced dry and/or canned food.

Can feline leukaemia be prevented?

Yes, feline leukaemia can be prevented through vaccination. The World Small Animal Veterinary Association regularly updates their vaccination guidelines. They recommend all kittens are vaccinated from 8 weeks of age with a second dose 3-4 weeks later. Older cats should have two doses of vaccine 3-4 weeks apart. Both kittens and older cats need a 12 month booster and then the frequency after that depends on your cat’s lifestyle and level of risk. Your vet will be able to help you decide how often your cat needs a vaccine booster..

While it can be emotionally taxing to receive a cat leukaemia diagnosis, it's important to stay calm while you put together a plan with your veterinarian. The best course of action you can take is to follow their advice to a T.