Should I spay my cat?

Q: Stormi, my new kitten, will be an indoor-outdoor cat. I know she needs to be vaccinated and eventually sterilized, but isn't it better to let her have one litter of kittens before that?

A: Cats live longer, healthier lives if they don't have kittens and are sterilized between 2 and 6 months of age. Later sterilization increases the risk of mammary (breast) cancer, the third most common cancer in female cats.

Mammary cancer is aggressively malignant. By the time it's discovered, it has already spread to the other mammary glands, lymph nodes and lungs. Surgery and chemotherapy are ineffective, so survival is less than a year.

The risk is decreased by sterilization, called spay surgery in females. Cats spayed by 6 and 12 months have 91% and 86% decreased risk, respectively, of developing mammary cancer. Waiting until the cat is 2 years old decreases risk only 11%.

Yet another reason to have Stormi spayed is to prevent uterine infection, which strikes 1 in 4 unspayed cats.

Have your veterinarian spay Stormi as soon as her vaccination series is complete, or she may surprise you by going into heat. Typical heat behaviors include rubbing, nuzzling, rolling, crying, yowling, raising her behind and spraying urine.

Female cats are seasonally polyestrus, which means they are in heat during seasons with increasing and long daylight, and they have multiple ("poly-") heat cycles ("-estrus"). As daylight increases in January, female cats as young as 4 months go into heat, and they continue to have weeklong heat cycles through the end of summer.

If the cat isn't bred during her first heat, she goes into heat about a week later. This pattern of recurrent heat cycles makes it seem as though the unspayed cat is always in heat.

Cats are pregnant for two months, giving birth during the warm months of spring, summer and fall. It's not uncommon for a female to have two litters a year.

You can avert unpleasant heats, uterine infection and mammary cancer by having Stormi spayed soon.

Lee Pickett, V.M.D. practices companion animal medicine in North Carolina. Contact her at vet@askthevet.pet.