Q:My veterinarian doesn’t offer Lyme vaccination for my cats, who spend more time outside than my dogs. Is a vaccine available for felines?

A:A vaccine to prevent Lyme disease in cats is not available because it’s not clear that cats actually get the disease.

Lyme disease is caused by bacteria called Borrelia, which are carried by Ixodes ticks, including deer ticks, black-legged ticks, western black-legged ticks and bear ticks.

The larval stage of the tick acquires the bacteria when it bites an infected small mammal, bird or lizard. The larval tick transforms into a nymph, which takes a blood meal from a small animal, dog or human, infecting the host and then molting into an adult tick.

The adult takes a blood meal from a large mammal like a deer, human or dog, again infecting the host. Adult Ixodes ticks mate on deer and continue the life cycle.

In areas where Lyme disease is prevalent, half the Ixodes nymphs and adults carry Borrelia bacteria. After the tick feeds for 36 to 48 hours, some of the bacteria leave the tick and enter the host.

Dogs infected with Borrelia bacteria form antibodies to them. Some infected dogs also develop arthritis and kidney damage, though not all do.

In cats, Borrelia bacteria induce antibody formation but don’t cause clinical signs typical of Lyme disease, even after cats are infected twice.

Although cats are remarkably resistant to Lyme disease, they still need protection from ticks, which carry other serious diseases. Fortunately, veterinarians offer a variety of products that kill ticks and fleas and are safe for cats.