Feline Leukemia Virus Infection: Symptoms and Treatment Explained by a Veterinarian

If you rescue a cat, one of the tests recommended by veterinarians is the Feline Leukemia Virus (FeLV) test.

Feline leukemia virus is common in outdoor cats, and infection is often confirmed when they are rescued.

This article will explain Feline Leukemia Virus Infection.

Early Symptoms and Detection Methods of Feline Leukemia Virus Infection

Feline leukemia virus is a type of retrovirus, and a characteristic of this virus is that it adds its own genetic information to cat cells and multiplies the virus. The feline leukemia virus enters the cat's bone marrow, infects the white blood cells responsible for immunity, and causes abnormal white blood cells to proliferate.

Leukemia describes a condition where abnormal white blood cells proliferate, and normal immune function does not work. The blood does not appear white, but when viewed under a microscope, only white blood cells are seen, hence the name leukemia.

Routes of Infection

Feline leukemia virus is present in saliva and nasal discharge, and contact infection occurs through mutual grooming between cats or by using the same food bowls. In addition, infection can also occur through the placenta or mating. The infectivity itself is not strong, and merely passing by does not cause infection.

It is common in outdoor cats, often seen between 1 and 6 years of age.

Symptoms

Symptoms in cats infected with feline leukemia vary, but generally include loss of appetite, weight loss, and lethargy. As white blood cells do not function normally, an immunocompromised state occurs, leading to stomatitis. It is also known to cause lymphoma in the chest, kidneys, and eyes.

Since the virus enters the bone marrow, fever, anemia, and bleeding tendencies may also occur.

Due to a weakened immune system, cats become more susceptible to various pathogens, and symptoms can vary widely.

Diagnosis Methods

Veterinarians diagnose it using kits that detect the virus in the cat's blood. Many types also detect feline immunodeficiency virus (FIV) simultaneously, so this test may be recommended if you adopt a rescue cat. Some rescue facilities may have already performed the test, and there may be owners who care for cats after being informed that they are positive for feline leukemia virus.

The test itself requires only a small amount of blood. Although the detection time varies depending on the test kit, results are available in about 20 minutes from blood collection. However, since the virus cannot be detected until about two months after infection, it is recommended to be tested at the time of rescue and two months after rescue.

Treatment for Feline Leukemia Virus Infection

Unfortunately, there is no cure for feline leukemia virus.

Because symptoms vary, symptomatic treatment is administered according to the symptoms. For example, if there is severe anemia, a blood transfusion is given; if there is fever, antibiotics are administered; if there is stomatitis, anti-inflammatory drugs are used; and if lymphoma has developed, chemotherapy is performed. Interferon therapy may also be used to activate the body's immune response to the virus.

Prevention Methods

It is important to avoid contact with cats carrying the feline leukemia virus. Since the feline leukemia virus can be transmitted simply by sharing food bowls, if a cohabiting cat has feline leukemia, all food bowls and living spaces must be separated. Ideally, if you come into contact with a cat with leukemia, you, the owner, should also change your clothes as a preventive measure.

Vaccination against feline leukemia virus can suppress infection and development of the disease. However, even with vaccination, it is not possible to live with an infected cat; infected cats must be isolated.

Furthermore, in veterinary medicine, it is known that a malignant tumor called fibrosarcoma rarely occurs at the injection site of the feline leukemia virus vaccine. Therefore, it is advised not to vaccinate against feline leukemia virus too frequently. Current vaccination programs (guidelines for vaccination) recommend vaccination once every three years.

Prognosis

If a cat is infected with feline leukemia virus, it can develop a persistent infection where the virus is present in the body without symptoms.

Generally, persistent infection is established in almost 100% of cases when neonates are infected, but it is said to occur in 25% of infections after three months of age, and rarely after one year of age. If persistent infection occurs, most cases result in death within four years.

If a cat is infected shortly after birth, it will need to live with feline leukemia. However, if diagnosed positive later in life, the virus may be cleared by the body's immune system. Therefore, retesting is recommended four months after a positive diagnosis. If the result is negative, it is likely that the virus has been cleared. If it remains positive, however, it is regrettable that a persistent infection is likely.

Severe symptoms do not appear immediately after persistent infection; it often takes a considerable amount of time for symptoms to emerge. If there are no symptoms, it is important to have regular veterinary check-ups and maintain the current condition. Additionally, stress can weaken the immune system. Try to create a living environment that minimizes stress.

If you have other cats in the household, take measures to prevent them from becoming infected.

Summary

There is no cure for feline leukemia virus infection if it becomes persistent. Therefore, preventing infection from other cats is crucial.

Also, some cats at adoption events test positive for feline leukemia virus. If a cat develops feline leukemia, some form of treatment will always be necessary. Before deciding to adopt, consider carefully whether you can afford the treatment costs for that cat and take measures to prevent other cats from being infected, rather than acting purely out of emotion.