Feline Leukemia – Causes

Feline leukemia is a nasty form of cancer that aggressively attacks and weakens its host’s immune system and renders the infected cat susceptible to other forms of cancer and disease. Caused by the feline leukemia virus (FeLV), feline leukemia is a patient and stealthy invader, sometimes remaining dormant for years following initial exposure, and an equal opportunity attacker, as the feline leukemia virus can lead to the development of more cancers and immunodeficiency disorders than any other infectious agent. In fact, FeLV is the major cause of cancer in cats in general and is second only to trauma as the leading cause of death in housecats.

The following three subgroups are contained within the feline leukemia virus:

• Subgroup A – The most common of the subgroups, Subgroup A causes the immunosuppression that renders FeLV-positive cats susceptible to other infections.
• Subgroup B – When joined with Subgroup A, the two subgroups together cause many of the FeLV-mediated cancers.
• Subgroup C – The least common of the three subgroups, Subgroup C causes severe anemia and bone marrow damage.

The protein FOCMA (feline oncovirus-associated cell membrane antigen) may be found on some feline cancer cells in both FeLV-positive and FeLV-negative cats. Cats that have antibodies to this protein have protection from certain cancers like lymphomas but are not protected against FeLV itself or other Feline Leukemia-mediated diseases.

Infected saliva transmits FeLV from cat to cat through a healthy cat’s repeated and prolonged exposure to shared contaminated water and food bowls, mutual grooming and cat bites. The virus also spreads through contact with infected urine and feces, especially in a multi-cat household where one of the cats has been infected. Kittens, which have less resistance to disease, may become infected in utero or through their mother’s milk.

Illness, overcrowding and poor sanitation stress and weaken a cat’s immune system and her resistance to infection. Cats do not react well to change in any form, especially changes in environment caused by moving house and the addition or death of a family member. Anxiety and stress caused by environmental changes, a pre-existing illness, the fluid inter-feline dynamics of a multi-cat household and the invasion of bacteria and other agents that thrive in filthy living conditions all wear down a cat’s natural defenses. Poor immune system health clearly plays an important role in the development of feline leukemia.

Poor nutrition negatively impacts immune system health. Cats require much more protein in their diets than dogs do and should be fed cat food products containing only specifically named animal protein sources, not by-products or meat and bone meals. High quality protein supports healthy immune system function. Antioxidants ward off disease and infection. Any prolonged diet lacking in high quality protein and antioxidants weakens the immune system to the point where the feline leukemia virus encounters little or no resistance after exposure.