Feline leukemia (FELv) is an infection caused by a retrovirus. This illness causes cancer. This illness is one of the most dangerous and insidious illness of cats which is given by one cat to the
other (but not to humans!). After entering the cat's organism, months or even years can go by without any symptom. Infected and virus carrier cat passes the virus through saliva, runny nose,
urine and close contact (playing with each other, cleaning each other).
Of course it can be passed through through a litter box or food dish used by an infected cat, etc.

Virus carrier female cats infects their babies through placenta, so they born infected. In a lucky situation our when our pet meets the virus, it has strong immune system which destroys the virus.
Usually our pets organism is unable to defend itself. The virus proliferates in the organism but doesn't cause sickness but the cat carries and able to pass the virus for a long time (infection without
symptoms). It is possible if there is a balance between the virus and the immune system of the cat.

But this condition is fragile and the immune system or the virus can became stronger. If the virus is stronger our pet will be ill, if the immune system is stronger, it will stay healthy. If the organism is weakened by stress, helminth or an other illness the virus can win.
In case of setback the resistivity of the organism is so weak that the virus can proliferate in the whole organism. It mostly happens if the infected animal is old, really young or already weak because of an other illness. Shortly after the infection these cats get ill and may pass away.

Symptoms of the feline leukemia can be various. Ill pets are usually brought to vet because they refuse food and grow thinner. Not really high fever is a common symptom and other symptoms
-hampered respiration, diarrhea, disorder in the nervous system- are depending on which organ is attacked by the virus. In case of these symptoms the illness is in the final phase, and cannot be cured.
In veterinary practice the fast diagnosis of the illness is really important. It is possible with special laboratory-examinations (ELISA) and rapid tests.

At clinics rapid tests are usually used. For this some drop of blood is needed and the result is available in five minutes. The examination has to be made two times in every 8-10 weeks. For example the first positive test doesn't mean that the the leukemia virus is able to stay durative in the organism of the cat because it is possible that the cat is able to product enough antibody and to
destroy all the virus. Therefore only the second test can prove that the cat is carrier of the virus or also passes the virus. It is the same if the first test is negative or doubtful.

Some years ago a vaccination was developed. Nowadays it is common to use this vaccinate. The vet must warn the owner of the cat that the “combined vaccination” doesn't contain the component against leukemia. The leukemia vaccination has to be given two times in every two weeks and after once a year.
The feline leukemia makes the immune system weaker and other illnesses can easily attack the organ of the cat (Feline viral rhinotracheitis /FVR, FIP/ feline immunodeficiency /FIV or cat
AIDS/). More illnesses at the same time can effect a really complex clinical picture and danger our pet's life. In case of every chronic illness there is a chance of feline leukemia.

Dr József Péli