There is no medical evidence to justify allowing a dog or cat to have a litter before spaying. In fact, spaying female dogs and cats eliminates the possibility of developing uterine or ovarian cancer and greatly reduces the threat of mammary cancer. MYTH Behavior is adversely affected by sterilization. The only changes in dog and cat behavior after spaying or neutering are positive changes.
Male cats tend to reduce territorial spraying, depending on their age at neutering.
Neutered dogs and cats fight less, resulting in fewer bite and scratch wounds and lessening the spread of contagious diseases. Male dogs and cats tend to stay home more after neutering because they no longer wander in search of a mate. MYTH Animals are less active and overweight after spaying or neutering. As any animal matures, it is necessary for human guardians to adjust dietary intake to compensate for more sedentary lifestyles. MYTH Males don't have litters, so we don't need to neuter them.