Feline Leukemia Virus (FeLV)

What is FeLV? The Feline leukemia virus is a virus that suppresses the immune system and renders the cat more susceptible to other viral and bacterial organisms as well as to some types of cancer. Signs of infection can include: vomiting, diarrhea, weight loss, decreased appetite, lethargy and anemia. How could my cat get FeLV? One of two ways: 1) the virus can cross the placenta and infect kittens of a FeLV positive queen or shortly after birth, through nursing and grooming. 2) a kitten or an adult cat can be exposed to the virus through contact with other cats, either in a cattery or a multi-cat household or by going outdoors. Exchange of body fluids, especially saliva but also, feces and respiratory secretions, is required for transmission of the virus. Thus, cat fights resulting in bite wounds and sharing food and water bowls with FeLV positive cats can put a FeLV negative cat at risk for acquiring the virus. What determines if my cat gets this virus? If exposed, a cat may or may not become infected. This depends on: 1) the cat's immune system- in cases of stress (such as a change in environment or introduction of another animal into the household) or if the cat is young or already sick, it will be more likely to become infected with FeLV. 2) the degree of exposure- if the cat receives a massive exposure or if exposed over a long period of time, its immune system may be overwhelmed and become infected with FeLV. Testing for FeLV It is important to test all cats for FeLV, especially cats being newly introduced into a household. The virus is detected by using a blood test (FeLV test). Tears and saliva can also be used, but these tests are less sensitive in detecting the virus. Negative results to the FeLV test means that the cat is not shedding the virus. However, because there is a great deal of variability between the time of infection and the time of shedding of the virus, in some instances, a cat that tests negative initially can test positive later. Once a cat's status has been determined, it can be vaccinated. Depending on your cat's lifestyle, vaccination for FeLV may or may not be recommended. Cats that make no contact with other cats are at very low risk of contracting FeLV. Thus, these cats may not need to be vaccinated against FeLV. On the other hand, cats that go outdoors and especially those that fight are at high risk for acquiring the virus. If a cat tests positive, there is no protection or harm by giving the FeLV vaccine. Vaccination for FeLV To start and complete the series of FeLV vaccines, 2 initial vaccines are needed, 2-3 weeks apart. This is followed by boosters every 1-3 years, depending on your cat's risk of exposure to FeLV. While vaccination minimizes the chance of a cat contracting FeLV, even a vaccinated cat can occasionally acquire the virus. This can occur when the cat is unable to fully respond to the vaccine or if an exposure to FeLV overwhelms the cat's immunity. Nonetheless, the vaccine does offer about 80% chance of protection. What does it mean if my cat tests positive for FeLV? It means that your cat is infected and is actively shedding the virus. When a cat is infected, it may: 1) Rapidly develop immunity and revert to a non-infected state as it develops antibodies to eliminate the virus. For this reason, if a cat tests positive for FeLV, it is recommended to retest in 6-8 weeks to re-evaluate the cat's status. 2) May be infected and continue to test positive with later testing. It many not develop any signs of illness but may carry the virus for an indefinite period of time. A healthy FeLV positive cat may live out a normal life span with little medical problems until late in life. 3) become ill soon afterwards with any FeLV-related disease What if my cat tests positive but isn't sick and what can I do to help him/her? If your cat tests positive for FeLV for 2 consecutive blood tests but isn't ill, the cat is still shedding the virus and is infectious to other cats. Ideally, it should be kept indoors and isolated from other cats. This not only helps to limit spreading the virus to others but also protects the FeLV-positive cat since its immune system is more susceptible to infections. This includes taking the precautions of feeding and offering water separately and washing hands after contact. Since the virus is short-lived in the environment, thorough cleaning with most common household disinfectants is sufficient to eliminate the virus. Without signs of illness, a FeLV positive cat can live a good quality of life, but it does need to be protected against stressful events and exposure to other cats and their illnesses. Many experiments have been done with anti-viral drugs and antibody therapy, but the results are inconclusive. Other studies have shown that the administration of human interferon as an oral solution on a daily basis to FeLV positive cats may prolong survival. There are no negative side-effects, and it is cost effective for long term use. What if my cat is ill and how is FeLV treated? While there is no treatment for the underlying FeLV virus, the secondary FeLV-related conditions respond differently to treatment. Supportive treatment including antibiotics, fluids and blood transfusions can sometimes help FeLV positive cats that are experiencing an acute illness. In cases of FeLV-induced cancer, chemotherapy can sometimes result in a remission of clinical signs for several weeks to a few years. Chemotherapy can be effective in controlling, not eliminating the cancer, and FeLV status does not appear to influence a cat's response to treatment. In most cases of FeLV, however, the cat eventually succumbs to the disease. What diseases can be associated with FeLV? FeLV-related diseases include: anemia (low red blood counts); leukopenia (low white blood counts); kidney disease; liver disease; leukemias (cancer of the bone marrow) and lymphoma (cancer of the lymph nodes). Lymphoma can result in cancer of the lymph nodes in the mediastinum (in the chest) and mesenteric region (in the abdomen); gastrointestinal tract (stomach and small intestines) ; kidneys or spinal cord. Many diseases can be indirectly caused by FeLV since it suppresses the immune system, often resulting in chronic skin, teeth, gastrointestinal or urinary tract problems. What precautions should I take for my other cats if I have a FeLV-positive cat? For cats that have tested negative for FeLV but are living in a household with a FeLV positive cat, it is recommended to vaccinate the FeLV negative cats. The risk to the adult FeLV negative cat of acquiring FeLV is 10-15% if they are exposed several months to the FeLV positive cat. Isolation of a FeLV positive cat in a multi-cat household is recommended but is not always feasible. Keeping a FeLV positive cat indoors will help limit the spread of the virus to other cats and help protect that individual from exposure to other cats' diseases and bites. After the loss of a FeLV positive cat, a prolonged waiting period is not needed before introducing a new cat in the household. Are there any risks to me? No humans have been found to be infected with FeLV nor has any case of human leukemia been traced to FeLV. FeLV does not appear to be a human health hazard. If you have questions regarding this disease and its treatment, don't hesitate to contact your veterinarian. The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.