One of the most dreaded diseases that affect cats is the feline leukemia virus (FeLV), which is to blame for approximately a third of their cancer-related fatalities.
Even though estimates vary by location, the incidence of the disease in healthy free-ranging cats has been reported to be as low as 1-3%, this complex and frequently misunderstood condition was originally discovered in 1964 and is still one of the most researched feline medical issues. The development of therapeutic regimens has advanced, but no treatment has succeeded in curing the virus or getting it off the cat after it has become established.
Leukemia is an issue mainly because it can go unnoticed in healthy herpes virus carriers and because it is still a lethal disease, even if there are no feline leukemia epidemics in shelters. The question of whether TNR programs and shelters should routinely screen for the virus and how to manage the seemingly healthy cats that test positive is one of the most contentious issues surrounding the condition for shelters.
Cause
A retrovirus that only affects cats and other members of the feline family causes feline leukemia. It is thought to be immune to human transmission. It is easily eliminated in the environment since it can be rendered inactive by heat, soap, the majority of disinfectants, and drying. It will only last outside the cat’s body for 24 to 48 hours, even in the ideal conditions.
For these reasons, cats may be kept in shelters safely with little chance of disease transmission, but only if they are kept in individual cages and regulations about proper hygiene and hand washing before handling cats are properly followed. When healthy cats are infected and are deemed to be viremic, they will continuously release virus at levels that are comparable to those found in sick cats.
Transmission
Direct oronasal contact between cats, mutual grooming, sharing infected water bowls, and using the same litter box are the main ways that feline leukemia is disseminated. The virus is excreted in a variety of bodily fluids, including blood, urine, saliva, milk, tears, and snot. Saliva has larger levels of it than blood does. Infected needles, fomites (hands or other inanimate objects), surgical tools, and blood transfusions are additional ways it might spread. Additionally, extended waiting times are not necessary before adopting a new cat into a household that previously had a cat with leukemia.
Infected cats may test positive for the feline leukemia virus within a few days to a week, but healthy, immunocompetent cats will be able to get rid of the virus within about two weeks and will subsequently test negative. The virus develops itself in the bone marrow in the case of latent carriers, making routine testing potentially ineffective. Since latent carriers typically do not shed the virus, they are not contagious and may eventually be able to get rid of the illness.
The cat continues to test positive (is viremic) and finally becomes ill as a result of the cat’s immune system’s inability to develop a strong defense. The death rate for healthy, persistently viremic cats in multicat households is 50% in 2 years and 80% in 3 years, according to Greene’s infectious disease text, yet there are also evidence that many cats given the right care may survive for several years.
Symptoms
The signs of feline leukemia infection might be quite general and non-specific, such as vomiting, weight loss, lethargy, anemia, and so on. As the illness worsens, symptoms that are related to the organ system the virus has impacted may appear. For instance, diarrhea may be seen if the intestines are impacted. The most typical malignancies are lymphoma and leukemia.
There may be stillbirths and abortions. Due to the immunosuppressive nature of the infection, these cats are also vulnerable to infections by other organisms and frequently pass away from other illnesses. If routine FeLV testing is not done, it is typically recommended in cats with diseases that are resistant to treatment or in cats with recurrent fevers and other clinical disease symptoms.
Diagnostic Testing
Every cat should be informed about their feline leukemia status, according to the American Association of Feline Practitioners (AAFP). It is still up to the shelter to decide whether or not to assess the cat’s condition before adoption and whether doing so is the best use of its resources, if any. In shelters that group house cats or neuter them prior to adoption, screening tests should be performed early.
No healthy cat should ever be put to sleep because of the findings of a single test, regardless of the decision that is made. The tests are not always 100% reliable, and a positive result just means that the cat is infected with the virus. A comprehensive explanation of feline leukemia testing can be found on the AAFP website (www.aafponline.org). A list of some of the most significant testing principles is provided below.
- Although it is advised to only utilize serum or plasma, the ELISA test is frequently used in shelters and private practices to check for the presence of the leukemia virus (or antigen) in blood, tears, or saliva.
- It can be carried out on cats of any age because the test is unaffected by vaccinations or maternal antibodies (although newborns may not test positive for several weeks).
- Queens and each puppy in a litter should be checked separately.
- The test should be run at least a week after a leukemia exposure for optimum results. If the cat tests negative, it should be tested again, with the final test being done 90 days after the publicity to ensure the animal is in fact negative.
- Any healthy cat that tests positive needs to have the IFA test, which is regarded as confirming, performed again.
- Before making a final determination about a healthy cat, discrepancies between the findings of the ELISA and IFA tests should be clarified.
Treatment and Management
Options for treatment are outside the purview of this article. Since the shelter atmosphere is stressful and provides a chance for other diseases to infect these susceptible cats, treatment is not advised. Healthy FeLV positive cats need to be spayed, dewormed, FVRCP and rabies immunized, kept inside, and regularly watched for the emergence of other illness symptoms. They shouldn’t live with FIV-positive cats and should be housed separately. If adopted, they should go to a home without any other cats or a home with cats that have received the disease’s vaccine.
It is best to stay away from houses with kittens because they are typically far more likely to develop the illness than adult cats are. Owners should be informed of the condition, its dangers, and the cat’s prognosis. They should also be encouraged to feed their cats a comprehensive and balanced food and to inspect their cats’ mouths for dental problems on a regular basis.
Both stress and feeding children raw, undercooked, or unpasteurized food should be avoided. If they get sick, antiviral and immunotherapy treatment procedures may be started, but it’s important to keep in mind that while they might extend and enhance the quality of life, they don’t offer a cure.
There is a FeLV vaccination available. Cats should be screened before receiving the vaccine. Don’t immunize FeLV-positive cats. Although the vaccine is generally thought to be effective, routine usage in the shelter is not advised. In case a sarcoma develops that requires amputation of a limb, the vaccination should be administered subcutaneously (SQ) over the lateral portion of the left thigh. The vaccine has been linked to the development of vaccine-associated sarcomas (tumors).
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