Feline leukemia is a grave concern for cat owners, as it is a cancerous disease caused by the feline leukemia virus (FeLV). This virus not only leads to leukemia but can also result in various other cancers and immunodeficiency conditions. It’s worth noting that cats may remain asymptomatic for months or even years after being infected, making early detection a challenge. In the United States, approximately 2.3% of feline populations are affected by FeLV, which is a significant percentage that cannot be ignored.
Characteristics of the Feline Leukemia Virus
FeLV is a retrovirus, closely related to feline immunodeficiency virus (FIV) and the human immunodeficiency virus (HIV). Retroviruses are unique in that they contain RNA, which is transcribed into DNA within the host’s cells. It’s important to understand that these viruses are species-specific, meaning they cannot cross-infect between different species. FeLV, for instance, will only affect cats.
Retroviruses are also quite fragile, susceptible to inactivation by ultraviolet light, heat, detergents, and drying. Despite this, they have been a part of the natural world for millions of years.
Transmission and Prevalence of FeLV Infection
FeLV is highly transmissible, particularly through saliva, which often leads to transmission via mutual grooming or shared resources like food and water bowls. Bites are also a very efficient mode of transmission. The virus can be present in tears, urine, and feces, posing a risk in multi-cat households. Additionally, FeLV can be transmitted from a mother to her kittens in utero, or through her milk.
While the prevalence of FeLV in the general cat population is estimated to be between 1-2%, certain demographics are more vulnerable. Male cats, cats with outdoor access, and kittens are at higher risk of infection.
Outcomes and Associated Diseases Post-Infection
Following exposure to FeLV, cats may respond differently. Some may not become infected due to insufficient exposure or a robust immune response. Others may develop a latent infection, where the virus remains dormant without causing disease or shedding. However, some cats become persistently infected, leading to FeLV-associated diseases within a few years.
The age of the cat is a critical factor in determining the outcome of FeLV exposure. Kittens under 8 weeks of age are particularly susceptible to persistent viremia and permanent infection.
FeLV can cause a wide range of diseases, including weight loss, fever, immunodeficiency, anemia, immune-mediated diseases, reproductive problems, gastrointestinal issues, neurologic disorders, platelet disorders, lymphadenopathy, and various forms of cancer. It’s also linked to respiratory and eye problems, as well as oral diseases.
Diagnosis and Clinical Signs
The clinical signs of FeLV can vary widely due to the numerous body systems it can affect. Common initial signs include loss of appetite, fever, weight loss, and weakness. Serologic blood tests are typically used to detect FeLV antigens, with the ELISA test being a common initial screening method. Positive ELISA results should be confirmed with a test like the immunofluorescent antibody (IFA) test or polymerase chain reaction (PCR) test.
It’s important to remember that no test is 100% accurate, and guidelines from the American Association of Feline Practitioners (AAFP) recommend testing all cats for FeLV, including retesting during sickness, when adopting, after potential exposures, and prior to initial FeLV vaccination.
Management and Prevention of FeLV Infection
FeLV-infected cats may live for years with proper management. Stress reduction, limited exposure to other ill animals, and maintaining the cat indoors are crucial. Veterinarians may adjust vaccination protocols, diet, and treatments based on the cat’s FeLV status. Clinically ill cats will need supportive care and targeted treatments for any FeLV-related diseases.
Vaccination against FeLV is available and generally recommended for cats with outdoor access or those who interact with other cats. However, it’s important to note that no vaccine offers 100% protection,