Cat Behavior and Training: Cat Neutering and Behavior

Cats that are kept for companionship are typically neutered (castrated), unless they are intended to be used as breeding stock. Neutering prevents accidental or indiscriminate breeding and reduces the frequency of undesirable sexual behaviors such as mounting and marking.

Neutering may also prevent some types of aggressive behavior. Unneutered (intact or tomcat) males with access to outdoor space are more likely to roam, as they seek mates and fight with other males to maintain their territory. In addition, tomcat urine is particularly malodorous. Overall, a neutered male cat may be a more pleasant household companion.

How does castration affect behavior?

A cat’s temperament and personality are based mainly on genetics, the health and behavior of the queen, and very early experiences. Training and home environment have a great influence on behavior, but these influences occur both in the presence and absence of male hormones. The only behaviors affected by castration are those under the influence of male hormones (sexually dimorphic behaviors). For example, castration may reduce mounting and marking but is unlikely to reduce anxiety or hyperactivity.

Some types of aggressive behavior may decrease following castration, while others will not. If your cat exhibits aggressive behavior, consult with your veterinarian or a veterinary behaviorist about treatment strategies.

What is neutering?

The operation of neutering or castration of male cats is called an orchidectomy. The procedure involves general and local anesthesia, and both testicles are removed through a local incision. External sutures are not generally required. In male sexual development, the two testicles descend from a position inside the abdominal cavity down to the scrotal sac, where they can be easily accessed for the castration procedure.

Sometimes, the testicles do not descend fully but remain either in the abdomen or in the inguinal canal – a condition known as cryptorchidism. Cats with this condition require more extensive surgery to locate and properly remove the “retained” testicles. When undescended testicles are not removed, they continue to produce sexual hormones that contribute to undesirable behaviors and may also contribute to health problems as cats age.

What are the benefits of neutering?

Population control

Millions of cats are destroyed across North America each year because there are far more cats born than homes available. A single male cat can father many litters, so neutering intact males is essential for population control. Although sexual desire will be greatly reduced by castration, some males continue to show sexual interest in females.


The most reported behavior problem in cats of all ages is indoor elimination at locations other than the litter box. Many of these cases involve cats that spray or mark walls and other vertical household objects. Adult male cats have an extremely strong urge to mark territory, both indoors and out. Neutering reduces or eliminates spraying in approximately 85% of male cats.


House cats, whether neutered or intact, can get into fights, but two intact males may be more likely to fight. This increased fighting is a direct result of sexual competition between male cats, and because intact male cats roam and protect a much larger territory. Wounds are prone to infection, often resulting in abscesses that can cause serious illness if left untreated. Neutering reduces fighting and abscess development in male cats.

Roaming and sexual attraction

Intact males have much larger territories and wander greater distances than females and neutered males. The urge to roam may be particularly strong during mating season. Castration reduces roaming in approximately 90% of cases.

Although neutering greatly reduces sexual interest, some males may continue to be attracted to, and mate with females. Both neutered and unneutered males can engage in masturbation.

Physical changes

Male urine odor is particularly strong and pungent. Castration creates a more normal urine odor. Cat caregivers often claim that their intact males became cleaner, less odorous, and better at self-grooming after neutering. Some secondary sexual characteristics can be dramatically reduced after neutering, such as over-productive tail glands that cause "stud tail".

Does neutering lead to any adverse effects on health or behavior?

Neutered male cats have different energy requirements than intact males. Your veterinarian can advise you on an appropriate daily caloric intake for your cat and can design an appropriate exercise and feeding routine. It is much easier to prevent your neutered cat from gaining weight in the first place than to put your cat on a weight-loss diet.

Be sure to provide your cat with plenty of opportunities for exercise. This can include outdoor walks on a leash, outdoor play in a safe enclosure, daily interactive play, and providing food in toys that are scattered throughout the house.  

Most behavior changes following castration are positive, such as a reduction in undesirable, sexually driven behaviors such as marking. Behaviors that develop independent of hormonal influences, such as hunting, are not affected. Regardless of the age at which it is done, there is no strong evidence that neutering stunts growth or prevents urethral development.  

Importantly, though neutering may prevent the development of sexually dimorphic behaviors, once these behaviors have developed, castration may not be curative. Every attempt should be made to neuter before puberty, before the cat develops problems, experiences, and habits associated with sexual maturity.