Management of FeLV Even in the case of progressive infection, cats that test positive for FeLV may go on to live for many years. For this reason, it is never appropriate to euthanize a cat solely based on positive FeLV testing (American Association of Feline Practitioners, 2009). It is important to provide client education on this topic, because clients may jump to conclusions and assume that euthanasia is the best course of action following a positive FeLV test. Although FeLV cannot be cured, a number of strategies can be used to manage this condition. Recommended management strategies will depend on the specific manifestations of FeLV infection that are observed in a particular patient, as each of these manifestations is managed differently. Lymphoma is the most commonly reported tumor in FeLV-infected cats. The presence of FeLV infection does not affect the management strategies for feline lymphoma or its response to therapy. These cats can be treated with conventional lymphoma therapies. A number of chemotherapy protocols have been utilized for the treatment of feline lymphoma. Prednisone alone may provide some relief of clinical signs, offering a temporary improvement in quality of life. Chemotherapeutic protocols—including cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) and cyclophosphamide, vincristine, and prednisone (COP)—are frequently utilized when owners are interested in pursuing more aggressive treatment. Cats that achieve complete remission after induction of chemotherapy often go on to have long disease-free intervals, providing substantial benefits in mean survival time and overall quality of life. Cats with mediastinal and multicentric lymphoma, in particular, frequently achieve complete remission with chemotherapy (up to 90% of cats) and one-year survival rates of up to approximately 55% have been reported (Litster, 2015a). Cats with aggressive GI lymphoma have a more guarded prognosis; approximately 50% of cats will achieve a complete remission with chemotherapy, and one-year survival rates of 20% to 40% are typically observed in this group (Litster, 2015a). Myelosuppression is the most serious consequence of FeLV infection and carries a poor prognosis. Whole blood transfusions may be beneficial for the short-term treatment of anemia, but this often becomes impractical for clients and pets because of associated costs and the immune consequences of repeated blood transfusions. Recombinant human erythropoietin (rHuEPO) can also be used in cats with clinical signs associated with anemia, usually when hematocrit (HCT) is less than 20% (Litster, 2015a). This drug is typically administered every 48 hours (100 U/kg SQ) for 3 to 4 weeks of treatment before seeing an effect and is continued long-term if it is beneficial for the patient. Successful treatment should elevate the HCT to 30% or higher. Unfortunately, approximately 20% to 30% of treated cats will develop anti-erythropoietin antibodies that will adversely affect the therapy’s efficacy. These antibodies Prevention of FeLV Feline leukemia is a serious disease. While some cats may develop regressive infections or survive for long periods of time, most infected cats living in multi-cat homes are expected to die within 3 years (Litster, 2015a). Therefore, prevention of FeLV is essential. The AAFP currently recommends that FeLV vaccination be regarded as a core vaccine in kittens under one year old (Stone et al., 2020). While the decision to vaccinate adult cats is based on risk, kittens are more susceptible to FeLV infection than adult cats; this is one motivator behind
typically develop 6 to 12 months into treatment, rendering further therapy ineffective (Litster, 2015a). In cats with neutropenia, recombinant human granulocyte colony- stimulating factor (rHuG-CSF, filgrastim) may be used to stimulate neutrophil production. Like rHeEPO, however, antibody development often occurs and limits the benefits of this product (Litster, 2015a). Cats with FeLV are typically more susceptible to infection than immunocompetent cats. It is important that any infections that do develop in FeLV-infected cats be treated promptly, as these infections can quickly become severe and life-threatening. Good nursing care is also essential to maintaining quality of life in cats with FeLV. Keeping immunosuppressed cats clean and well-groomed can decrease infection risks, while optimal nutrition can promote overall health. Asymptomatic cats with FeLV should be housed indoors. This serves two purposes. First, keeping an FeLV-positive cat indoors prevents transmission to other cats in the neighborhood. Equally important, however, is the fact that keeping an FeLV-positive cat indoors will decrease the cat’s exposure to pathogens that may result in opportunistic infections. Emphasize both of these benefits to clients, in order to improve their likelihood of compliance. Keeping an FeLV-positive cat indoors is not simply a public service; it also benefits the infected cat. Cats with FeLV should receive a comprehensive physical exam every six months. This will aid in the early detection of opportunistic infections and other sequelae of FeLV infection. Additionally, infected cats should receive fecal parasite examinations twice yearly to assess for the presence of intestinal parasites and remain on year-round broad- spectrum parasite prevention. Cats with FeLV are significantly immunosuppressed. Therefore, it is essential to maintain their immunity against infectious disease with effective vaccination strategies. All FeLV-positive cats should receive core vaccines on a regular basis. There is some evidence to suggest that FeLV-positive cats may not adequately respond to vaccination or may experience a shorter duration of immunity (Hartmann et al., 2022a). Therefore, annual vaccination may be considered, especially for cats that are high risk of infectious diseases exposure (multi-cat homes, etc.). Historically, some veterinarians have recommended using inactivated vaccines for patients with FeLV, in order to avoid potential complications associated with the use of modified live vaccines in immunosuppressed cats. However, there is a lack of evidence to suggest that modified live vaccines are associated with adverse events in FeLV-positive patients (Hartmann et al., 2022b). Therefore, as there is no evidence to support this recommendation, veterinarians should feel free to vaccinate FeLV-positive cats with their vaccine of choice. the recommendation to vaccinate all kittens. Additionally, many owners do not determine whether their cat will live indoors or outdoors until it reaches adulthood. This delayed decision-making may leave cats potentially vulnerable to infection, because clients may not remember to contact their veterinarian before making changes in their cat’s lifestyle (Stone et al., 2020). Feline leukemia vaccines can be given to cats as young as eight weeks of age (Stone et al., 2020). The vaccine should then be boosted three to four weeks later. A kitten
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