Spaying or neutering will keep your dog from getting pregnant or impregnating another dog. Females get the spay surgery, which removes the ovaries and uterus, while a neuter surgery removes a male dog's testicles.

If you're cringing after reading this last sentence, consider this: the surgery provides many health and behavior benefits, and you won't find yourself with a bunch of puppies who need homes other than yours.

Next, throw out the persistent myth that sterilization changes a dog's temperament. In fact, dogs will be just as playful, friendly, aloof, timid, happy, anxious, silly, affectionate, food-motivated, or gentle as before being fixed. The only difference is males will be less likely to be aggressive and to roam.

What it does for your dog

The surgery has many benefits other than preventing unwanted puppies.

• Spayed before her first heat, a female has almost zero chance of getting mammary gland cancer. After the first heat, the chance is only 7 percent; 25 percent after the second heat. Past that (even far, far past), spaying will still reduce risk.
• Spaying prevents pyometra, a common, life-threatening infection of the uterus. Typically, it's middle-aged (or older) females who get it, about six weeks after a heat cycle. The treatment is an emergency spay.
• Neutering prevents some cancers of the testicle and anus, and it helps prevent some significant prostate problems in males.
• The best part is that after neutering, male pups change from juvenile delinquents into pillars of the community (although some will still lift a leg on the pillar). Males are less aggressive without that testosterone jamming up their brains, they're less likely to roam (and they don't act like such escape-artist Houdini Hounds in order to get out), and they're less likely to hump and mark. You'll still see some of this behavior, mind you -- just less of it.