Virus disease in the cat:
FeLV = Feline Leukemia Virus or leucosis

Every cat owner who starts breeding will find it sooner or later. Before the cat can come to the male, a blood test must be performed. Testing is done for FeLV (leukemia) and FIV (AIDS). FeLV is a disease that is not only important for breeders with purebred cats, but also for owners of "normal" domestic cats, because unfortunately, FeLV occurs in all types of cats.

In the text below we describe as cat veterinarians what FeLV entails, infection, diagnosis, treatment and how to prevent it.

 What is FeLV for a disease?

FeLV is a virus disease with a fatal outcome. The virus can cause leukemia (white blood cell tumors), but this is not the disease that occurs most after infection. This is because the virus affects the cat's immune system (immunosuppression), making them more susceptible to infections.

The syndrome of FeLV is therefore mainly caused by secondary infections.

How can a cat become infected with the virus?

After infection, the virus spreads in the tonsils in the throat and spreads to the bone marrow, lymph vessels and lymph nodes. The virus enters the blood and from then on it can be demonstrated by means of a blood test. If the salivary gland is infected then the cat will shed virus and from now on the cat will be contagious to other cats!

In particular, saliva contains high concentrations of virus and this is also the main method of transmission from one cat to another. FeLV is mainly transmitted through long-term social contact with other cats. Consider eating from each other's bowls or washing each other, because the virus can be transmitted through saliva, blood, urine and faeces. A pregnant female cat can transmit the virus through her placenta to her kittens (and later through breast milk). This can lead to abortion or birth defects, but healthy kittens can also be born who remain virus carriers.

FeLV is mainly transmitted through long-term social contact, but also by a bite wound fighting. At FIV, on the other hand, the main transfer occurs much more through direct bite to fight and to a much lesser extent through long-term social contact.

Cats that live together in a group and do not fight with each other therefore also have a chance of infection if there is a cat with FeLV in the group.

Not all cats that get infected with the virus get sick.
Healthy, strong cats with a good immune system can fight and overcome the virus. These cats do not excrete a virus and do not get sick.

 Cats that cannot fight the virus get sick.
Cats that cannot fight the virus, for example due to a reduced resistance, will excrete the virus. They themselves are not yet ill but already contagious to other cats. They are therefore also called "carriers". In the course of a few months to years (3 years) they will start to show symptoms of disease.
There is an age resistance. • 70-100% will get sick with young kittens.
• For kittens 8-12 weeks old, 30-50% get sick.
• In adult cats, 10-20% get sick.

What are the symptoms of a cat with FeLV?

The most important are the secondary effects of infection due to reduced immunity, including FIP, toxoplasmosis, bacterial inflammation, gum disease, abscesses, skin inflammation and eye inflammation (uveitis). See photos below.

 FeLV disease symptoms:
• Tumors. The most common tumor is malignant lymphoma, but leukemia, tumors in the liver, kidneys, peritoneum or spleen can occur.
• Anemia because the bone marrow no longer functions properly.
• Slimming
• Shortness of breath
•Fever
• Slowness
• Swelling of lymph nodes
• Eye infections such as uveitis
•Bad food
• Reproduction problems for example abortion, death of newborn kittens, infertility.
• Paralysis symptoms

It depends on where the tumors are located and which organs are affected, which complaints the cat gets.

 How can FeLV be diagnosed?

FeLV diagnostics is performed in the context of prevention in cats that are used for breeding (tracing cats that excrete virus but are not yet sick themselves) and if cats have symptoms that suggest FeLV.
The test method used is the Snap Combo test (ELISA) from Idexx. With this test the virus is detected in the blood.
Some blood is taken from the cat and within a few minutes the result is known, you can wait for the result.

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