Feline Leukemia – Symptoms, Treatment & Prevention (VET SUGGESTIONS 2021)


Curiosity killed the cat, satisfaction brought it back, but now there’s another danger looming over it – Feline Leukemia Virus (FeLV). It is the most important cause of death in cats, causing a variety of disorders, including leukemia (cancer of the white blood cells), immunodeficiency and anemia.

FeLV holds importance among other feline diseases because of its effect on the immune system making the cat susceptible to other fatal infections. This disease has a worldwide occurrence, with an incidence of up to 50% in densely populated areas.

How is Feline Leukemia transmitted?

If your cat likes to stay inside and laze around, it has only a 3% chance of contracting this virus. But if it has a social life, unlike you, then it’s likely to catch this disease from any infected cats it comes in contact with.

This virus is shed in large quantities in saliva, milk, nasal secretions, urine and feces, thus close contact with an infected cat or its body secretions may make a cat susceptible to infection. However, this virus is not highly contagious and thus, requires a prolonged period of close contact for transmission. Activities like mating, grooming, and sharing litter trays and food bowls help in the easy transmission of disease.

The virus can also spread from the bite of an infected cat.

Kittens may acquire this virus from an infected mother, in the uterus or during nursing. However, this is rare as most infected queens become infertile or there is prenatal death of the kittens by abortion or resorption of fetuses.

Who is susceptible to FeLV?

Since this virus is species-specific, it can only infect members of the cat family. Humans and other animal species are not at risk of contracting FeLV.

Among cats, kittens are most vulnerable to FeLV and therefore, if exposed, risk of infection is high in them. Unvaccinated cats of all ages are also susceptible to infection. But as they grow older, their resistance towards the virus increases, and so they are less likely to contract the disease.

What happens when a cat gets exposed to FeLV?

Even though this disease has fatal consequences, cat owners need not worry because in 70% of the cases, exposure to the virus does not result in disease. These cats either resist infection or eliminate the virus on its own.

In some cases, a cat may not manifest signs of a disease, but still shed virus in its secretions and thus, acts as a carrier.

In the cats which are unable to fight off the infection, the disease progresses in 6 stages, out of which the 4th stage is significant. Upto this stage, the virus has entered the blood and disseminated to various organs of the body. The blood vascular and lymphatic systems get infected, along with the intestines. At this point, if the cat’s immune system successfully eliminates the virus, the cat has a chance at survival. But if it fails to fight off the infection, the disease progresses to the 5th stage and reaches a point of no return.

In this stage, the virus infects the bone marrow. This results in the formation of infected White Blood Cells (WBCs), which results in immunosuppression and predisposes the cats to secondary infections. In the 6th and final stage, the cat’s entire body gets overwhelmed by the viral infection. Now, the virus will remain in the cat’s body forever. Such persistently infected cats succumb to death within 3 years of diagnosis.

What are the symptoms of Feline Leukemia?

Most cats are asymptomatic for months or years after infection, as the virus remains in an inactive stage. But even at this stage, the cats can transmit the virus to other cats.

Once the virus gets activated, it manifests itself as follows-

  • Anemia
  • Immunosuppression
  • Increased susceptibility to infections
  • Loss of appetite & weight loss
  • Lethargy
  • Persistent diarrhoea
  • Infections of the external ear and skin, and poor coat conditions
  • Pale gums and other mucus membranes
  • Inflammation of gums (Gingivitis), nose and mouth (stomatitis)
  • Inflammation of cornea and moist tissues of the eye, and a variety of eye conditions
  • Infection of urinary bladder and respiratory tract
  • Warbly, uncoordinated appearance
  • Seizures and other neurological disorders
  • Reproductive failure and abortion
  • Lymphoma (cancer of lymphatic system)
  • Fibrosarcoma (cancer of fibrous connective tissue)

Note: Lymphoma and Fibrosarcoma are the final stages of the disease.

How is Feline Leukemia diagnosed?

The disease can be diagnosed by two types of tests:

  1. ELISA- It stands for Enzyme linked immunosorbent assay. This test detects free viral particles in the blood and tests positive in both early and later stages of infection. Your vet may recommend a second test after a month or two, to check if the virus has been eliminated from the body or if the infection still persists.
  2. IFA- It stands for Immunofluorescent Antibody Assay. It is recommended after a positive ELISA test. It helps determine if the infection has reached the later stages. This test detects the presence of FeLV within the white blood cells. This is an indication of infection in the bone marrow.

Treatment and Care for Feline Leukemia

There is presently no cure for Feline Leukemia. Even though cats infected with FeLV may have a comparatively shorter life-span, their time can be full of joy. Regular veterinary check-ups and good preventive measures can help these cats to feel well for some time.

These cats should be kept indoors and require greater care to protect them from any secondary infections. Special care must be given to their diet. Cats with cancer can be given chemotherapy. All FeLV-infected cats should be neutered to prevent transmission of disease via mating. However, the prognosis is grave for cats with bone marrow infection or widespread Lymphoma.

How can you prevent Feline Leukemia?

Vaccine against FeLV is available but it is only 85 to 98% effective in preventing the disease. It is not considered a core vaccine. Hence, the best way to protect your cat is by monitoring its activities and proper supervision to ensure they don’t come in contact with any infected cats. Any cat shouldn’t be introduced in a multi-cat household without getting tested for FeLV.

Only cats that test negative for FeLV should be vaccinated.

The vaccination schedule for FeLV is as follows-

  1. 1st dose at 8-9 weeks
  2. 2nd dose at 12 weeks
  3. Booster dose after 1 year

Subsequent booster doses may be given after 2-3 years or based on the risk of exposure to FeLV-positive cats. Take care to always consult a vet before getting your cat vaccinated.

It is a common belief that once a cat tests positive for FeLV, it is an automatic death sentence for them and hence, the cat should be put down. But don’t forget that a cat has nine lives. They fight and continue to survive even in the most difficult situations.

FeLV does reduce the lifespan of a cat, but several cases have been reported where cats enjoyed a good and healthy life despite being positive for FeLV. This has been possible because of good veterinary care and regular checkups.

Since this disease is feline specific, if your cat is an only cat in the household or lives with other animal species, you need not worry about transmission of the disease. If your cat is doing perfectly well, give it your love and support. Consider euthanasia only when there is no more treatment available that will improve your cat’s condition.

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