What Are the Symptoms of Feline Leukemia (FeLV)
Medically Reviewed by Dr. Sarah Jenkins, DVM, Feline Internal Medicine Specialist
Understanding Feline Leukemia
Feline Leukemia Virus (FeLV) is one of the most common and significant infectious diseases affecting cats worldwide. This retrovirus weakens a cat’s immune system and makes them more susceptible to a variety of other health problems. FeLV is incurable, but with proper management, many affected cats can live comfortable lives for years after diagnosis.
Understanding the symptoms of FeLV helps cat owners recognize the disease and seek appropriate veterinary care. Early detection allows for better management and helps prevent the spread of the virus to other cats.
How FeLV Spreads
FeLV spreads primarily through saliva, blood, nasal secretions, and from mother cats to their kittens during pregnancy or nursing. The most common routes of transmission include prolonged close contact, such as sharing food bowls or grooming each other, bite wounds, and vertical transmission from infected mothers. Outdoor cats and cats in multi-cat households face higher exposure risk.
Early Stages: Often No Obvious Signs
During the early stages of infection, many cats show no symptoms at all. The virus can take weeks or even months to produce noticeable effects. This is why testing is so important, especially for cats with unknown backgrounds or those who have been exposed to potentially infected cats.
Symptoms by Category
Immune System Suppression Signs
FeLV compromises the immune system, making cats vulnerable to secondary infections. These may include respiratory infections that keep returning, chronic gum disease, skin infections that don’t heal properly, and ear or eye infections that persist despite treatment. Cats may seem to catch every illness that comes along.
Anemia-Related Symptoms
The virus often affects the bone marrow’s ability to produce red blood cells. Signs of anemia include pale gums (the most obvious sign), weakness and lethargy, rapid breathing or breathing with mouth open, decreased interest in play or activities, and an unusual pale or whitish appearance to the inner ears and gums.
Gastrointestinal Issues
Many FeLV-positive cats experience digestive problems. These can manifest as loss of appetite or refusing food, weight loss despite eating, diarrhea that may come and go, vomiting, and difficulty swallowing or eating.
Neurological Symptoms
The virus can sometimes affect the nervous system. Affected cats may show disorientation or confusion, changes in personality or behavior, difficulty walking or uncoordinated movement, seizures, and paralysis or weakness in the legs.
Cancer-Related Signs
FeLV significantly increases the risk of lymphoma and leukemia. Signs may include lumps or swellings anywhere on the body, enlargement of lymph nodes, difficulty breathing if cancer affects the chest, and persistent lameness or bone pain.
Reproductive Problems
In pregnant cats, FeLV can cause stillbirths, miscarriages, or kittens who are weak at birth. Female cats may have irregular heat cycles or fail to conceive.
Other Common Signs
General symptoms that may appear include persistent fever that comes and goes, poor coat condition and grooming, swollen lymph nodes, excessive sleeping or hiding, and overall decline in health despite treatment.
Disease Progression Patterns
FeLV infection doesn’t affect all cats the same way. Some cats eliminate the virus and become immune. Others become carriers without showing symptoms. A third group develops FeLV-related diseases that may take months or years to become apparent.
The Importance of Testing
Because early FeLV infection often shows no symptoms, testing is essential. Your veterinarian can perform a simple blood test to determine whether your cat has been exposed to the virus. Kittens and any new cats entering a household should be tested before introduction to existing cats.
Protecting Other Cats
If your cat tests positive for FeLV, take precautions to prevent spreading the virus. Keep FeLV-positive cats indoors to protect them from exposure to other infections and to prevent transmission to other cats. If you have multiple cats, work with your veterinarian about whether separation is necessary.
Disclaimer: This article is for informational purposes only and does not constitute professional veterinary advice. If you suspect your cat may have been exposed to FeLV, or if your cat shows any of the symptoms described above, please consult a qualified veterinarian for proper testing and appropriate care.