Understanding how feline leukemia invades the blood of the cat is key to understanding why it spreads so quickly, and is so damaging to the immune system. When a cat is exposed to the feline leukemia virus, the virus takes over by imprinting its own DNA into a healthy cell. As a result, the formerly healthy cell is forced to reproduce the viral cells, causing the virus to spread quickly. This is why feline leukemia is considered a retrovirus. Other known retroviruses are HIV and AIDS.
How it Spreads
The spread of feline leukemia is caused by the transfer of the retrovirus from one cat to another, and sometimes indirectly from shared items, such as food bowls or litter boxes. When there are cats living together, it is common for the virus to spread quickly to all. Nursing kittens are extremely likely to contract the virus from an infected nursing mother, because the virus travels in the breast milk and is directly ingested.
Feline leukemia is a virus that damages the immune system. It is possible that a cat with feline leukemia will become anemic, or develop certain types of cancer and infections. The immune system of a cat with feline leukemia is extremely suppressed, which results in an environment in which cancer cells are not fought off, making cancers, such as lymphoma, a likelihood.
Once the virus has multiplied, it may attack the bone marrow of the cat. Bone marrow is where red and white blood cells are created, so the presence of the feline leukemia virus is particularly damaging. The virus may not attack the bone marrow right away; in fact, it has been known to lay dormant for several years before attacking. Once the virus attacks the bone marrow, the cat becomes unable to fight infections of any kind, as if the immune system is paralyzed.
Whether the virus has invaded the bone marrow determines the stage in which the virus is categorized.
Primary Viremia is the first stage of feline leukemia. This stage begins upon the transfer of the virus. Many cats can actually fight feline leukemia in this stage, and eradicate the virus before it reaches the second stage.
Secondary Viremia begins when the virus attacks the bone marrow of the animal. This means the virus has gained control of the immune system. At this point, the cat is unable to fight the virus, or any other infection.
How to Prevent Feline Leukemia
Preventing feline leukemia is difficult, requiring prevention of exposure to the virus. Steps taken toward this goal can really only reduce the likelihood of exposure, unless cats are always kept indoors and are never exposed to any untested animals. If you have infected cats, and want to keep the other uninfected cats free of the virus, it takes a diligent separation of cats, litter boxes, and feeding bowls. There is a vaccination available for uninfected cats; however, it does not guarantee protection against the virus: the cat may already have been exposed or may have been exposed to a strain not included in the vaccine.
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.
More on Diseases in Cats:
Feline Immunodeficiency Virus
Heart Disease in Cats and Dogs