By John Koch, DVMQuestion: I have an indoor cat that never is allowed outside. The other day the little rascal managed to sneak out. I found him nose-to-nose to my neighbor's cat. A week later, I found out my neighbor's cat has feline leukemia. I never had my cat vaccinated for leukemia because he is an indoor cat. What are the chances my cat will get leukemia?
Answer: His unvaccinated status is indeed a reason to be concerned. A recent study of 27,976 cats showed that 13.3 percent were infected with leukemia. Other studies have shown even higher incidence of infection. Feline leukemia is a deadly disease.
Twenty-eight percent of exposed cats do not get infected, either because of an inherent resistance to infection or because of insufficient exposure. If your cat is in this group, you are home free.
Thirty percent of exposed cats develop an active infection. Initially these cats appear to be healthy. Then they become ill with any of a variety of different clinical syndromes. The bottom line is that within six months, 33 percent of these cats will be dead. At the end of two years, 63 percent are dead. At the end of 3.5 years, 83 percent are dead. If your cat is in this group, his prospects are not good.
Forty-two percent of exposed cats develop a transient infection, which is subsequently rejected by the immune system. These cats are not ill but may shed the virus and infect other felines for a variable period of time. Once the shedding stops, the virus usually becomes latent or dormant. These cats may carry the virus hidden within the body and never have any problems for the rest of their lives. On the other hand, this dormant virus may, due to stress of other unknown factors, suddenly again become active and cause illness. This group of cats is difficult to detect because none of the conventional tests is diagnostic. If your cat is in this group, you may be OK.
If you cat seems healthy after its exposure, have it tested for feline leukemia virus. If the test is negative, then have it vaccinated. Two vaccinations are required two to four weeks apart. Have it tested again three months later. If the second test is negative, then you can be 90 percent sure your cats is not infected. You can never be 100 percent sure. The safest thing is to have all cats vaccinated whether they are inside or not. Good luck!
Dr. Koch is a Cape Girardeau area veterinarian.