Pets are neutered to prevent undesired births and a variety of medical disorders in both males and females. More pets are being neutered at younger ages so they do not contribute to overpopulation.
Effect on Sexual Behavior
Sexual behavior usually disappears after neutering; however, some sexual behavior may persist. This is not necessarily an indication of incomplete surgical removal of the sexual organs.
Behavior that appears to be sexually motivated may be linked to other causes. Mounting by castrated dogs, for example, is usually a sign of dominance behavior. For most pets, neutering effectively eliminates development and progression of objectionable sexual behavior.
Effect on Aggression
Intact (unneutered) males and females are more likely to display aggression related to sexual behavior than neutered animals. Fighting, particularly in males and directed at other males, is less common after neutering.
The intensity of other types of aggression, such as dominance aggression, is also likely to be reduced. When related to the hormonal imbalance of false pregnancy or the agitation associated with estrus, irritable aggression in females is eliminated by spraying. If you worry that your dog will not protect your house after neutering, territorial aggression is not altered by neutering.
If your pet is not intended for breeding, neutering is advised to prevent aggressiveness related to sex hormones. Though neutering is not a treatment for aggression, it can help minimize the severity and escalation of aggressiveness and is often the first step toward resolving an aggressive behavior problem. Specific diagnosis of the type of aggression displayed by your pet, identification of the situations that trigger it, and retraining your pet to behave differently are still essential.
Effect on General Temperament
Many pet owners are concerned that a neutered pet will lose its vitality. Basic temperament and intelligence are not altered by neutering. In fact, many undesirable qualities under hormonal influence may resolve after surgery. Your pet will not become less affectionate or playful, nor will it resent you. You will not deprive your pet of any essential experiences. You will, however, be acting as a responsible, informed, and loving pet owner.
Effect on Escape and Roaming
A neutered pet is less likely to roam. Castrated male dogs and cats tend to patrol smaller outdoor areas and are less likely to engage in territorial conflicts with rivals. Spayed female cats may actually expand the territory patrolled. A pet that has already had successful escapes will probably continue to run away after it is neutered.
Effect on Inappropriate Elimination
Dogs and cats may urinate or defecate in undesirable areas of your home to stake territorial claims, relieve anxiety, and advertise reproductive status. This may continue long after the initial cause has passed. Because this behavior is only partly under hormonal control, male or female pets may begin to eliminate inappropriately even after neutering. Neutering an animal that has begun to inappropriately eliminate reduces the urine odor of intact adults and eliminates the contribution of hormonal factors. Unless underlying emotional or physical factors are controlled and environmental reminders are removed, the undesirable behavior may persist beyond neutering.