Feline leukemia virus
Feline leukosis is a serious viral disease that gradually weakens the cat's immune system. It can progress silently for months before visible signs appear. It is one of the leading causes of illness and death in cats worldwide.
What is it?
Feline leukosis is a serious viral disease that gradually weakens the cat's immune system. It can progress silently for months before visible signs appear. It is one of the leading causes of illness and death in cats worldwide.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
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Possible signs include weight loss, lack of appetite, lethargy, dull coat and recurrent infections. We may also observe pale gums, swollen lymph nodes or persistent digestive problems. Some cats remain carriers without showing visible symptoms for a long time.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by the Feline leukemia virus virus, a retrovirus that infects cells of the cat's immune system and bone marrow. This virus alters the normal production of blood cells and weakens the body's natural defenses.
Cats living in groups, having access to the outdoors or in contact with stray cats are more exposed. Unvaccinated kittens and cats are also at higher risk. Cohabitation with an infected cat greatly increases the chances of contamination.
Transmission
The virus is transmitted mainly through saliva, during prolonged contact between cats such as mutual grooming, sharing bowls or bites. It can also be transmitted from mother to kittens during gestation or breastfeeding. The virus does not survive long in the environment.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
If you observe signs suggestive of this disease in your cat, consult a veterinarian quickly for professional advice. Only a clinical examination and appropriate tests can confirm the situation and guide treatment. Never attempt to self-medicate.
Prevention
Vaccination is an effective means of prevention, to be discussed with a veterinarian depending on the cat's lifestyle. Limiting contact with cats of unknown status and testing new cats before their introduction into the household also helps reduce risks. Regular screening is recommended for cats at risk.
References
Content reviewed by the TunisieVet editorial team · Updated 18 August 2026
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