IS YOUR kitten vaccinated for feline leukemia virus?

You may not have thought to do so if you plan for him to be an indoor cat, but veterinary immunology expert Ronald Schultz, DVM, says that vaccination during kittenhood, followed by a single booster vaccination at 1 year of age, is the best way to prevent the spread of the disease and reduce its incidence.

Feline leukemia virus is the most common cause of cancer in cats and can cause various blood disorders. Some cats with the disease have poor immune systems and are unable to fight off infections. Signs of the disease include appetite loss, weight loss, poor coat condition, pale gums and persistent diarrhea. In the United States, approximately 2 percent to 3 percent of cats are infected with the virus. That's a low percentage, but it's still a serious disease that is highly communicable.

Infected cats shed the virus through bodily fluids such as saliva, milk, urine and feces. They can spread it when they groom other cats, share food and water bowls, or use the same litter box. Nursing mothers can pass it on through their milk. Kittens younger than 4 months and sick cats have the highest risk of infection and a higher rate of infection - 13 percent or more.

Cats who are vaccinated as kittens and boosted at 1 year will most likely have lifelong protection from the disease, even if they never receive another vaccination. Age-related resistance to the disease typically develops when cats are about 1 year old.

"Many cat owners whose pets don't go outside skip this vaccine, assuming that it's not necessary," Dr. Schultz says. "But cats can be escape artists or experience changes in lifestyle. Can we ever know when that animal is a kitten that it's never going to go outside and never be in contact with a potentially persistently viremic cat? The answer to that is no.

"Other concerns include potential reactions to the vaccine, which can include swelling or pain at the injection site, lethargy or fever. Some cats develop granulomas (inflammatory nodules) or sarcomas (soft tissue tumors) at the injection site. The University of California at Davis' School of Veterinary Medicine suggests using a recombinant FeLV vaccine, citing evidence that this type of vaccine is associated with a decreased risk of sarcoma formation.

The advisory panel of the American Association of Feline Practitioners seconds Dr. Schultz's advice to vaccinate kittens and boost the vaccination when they are a year old, but it does not consider FeLV a core vaccine, meaning one that is recommended for all cats. Adult cats should be vaccinated for FeLV only if they are at risk, according to the AAFP. Cats are at risk if they go outdoors, live with other cats who are known to be infected with FeLV, or live with other cats whose disease status is unknown.

If you discover that one of your cats has FeLV, have any other cats in your home tested for the disease. If they are infection-free, it's best to have them live separately from the infected cat so that they don't share food and water bowls or litter boxes. Ask your veterinarian about the pros and cons of having the uninfected cats vaccinated, since vaccination doesn't help cats who are already infected.

Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker.