What Does Neutering a Dog or Cat Mean?

Neutering in dogs and cats removes the ability of a male to produce young. In the U.S., cat and dog neutering is done surgically by making an incision over the scrotum or lower abdomen and removing the testicles. In Europe, some neutering is done by injection and no surgery is involved. Surgical neutering, which is also called orchidectomy (orchid=testicle and ectomy=removal) removes the source of most testosterone in a pet's body.

The best time to neuter pets is at any age from a few weeks old until they are seniors. Most males are neutered before they are 6 months old to prevent negative male behaviors from becoming established. For most families, pets neutered early are easier to discipline and they fit into family life better.

Key facts about neutering dogs and cats
  • Neutering at any age helps decrease the number of attacks on a male by other males
  • Neutered males are less likely to be the object of male aggression because they don't give off the scent of testosterone
When is the best time to neuter a dog or cat?

Males are neutered at all ages, from a few weeks old until they are seniors. Most males are neutered before they are 6 months old to prevent negative male behaviors from becoming established. For most families, pets neutered early are easier to discipline and they fit into family life better.

What are the benefits of neutering a dog or cat?

Neutering and spaying are the most common pet surgical procedures. Benefits of neutering your dog or cat include:

  • Prevents the birth of unwanted puppies and kittens
  • Lessens urine marking
  • Lessens fighting
  • Lessens cat yowling
  • Decreases tendency to mount if done early before mounting behavior established
  • Lessens running off to find females in heat
  • Prevents enlarged prostate problems
  • Removes the possibility of testicular cancer - especially a factor if testicles have not descended into the scrotum but are within the body
Are there negative health effects when neutering a pet?

While neutering offers many benefits, there are possible undesirable health and cosmetic changes. For example, pets surgically altered—especially those altered before they have reached their full growth-are generally taller, leaner, and less muscular. Their heads may also be narrower. With cats, the thicker cheeks (called shields) that develop in older males don't form. For most of us these are insignificant cosmetic changes, but for some, neutering before the pet is fully grown may not be cosmetically acceptable. In that case, pets can be neutered after developing adult male characteristics.

In addition to changes in appearance, there are changes in health with neutering. The following medical problems may increase with early neutering:

  • Incontinence
  • Bone and joint problems (knee injury due to cruciate rupture, hip dysplasia and bone cancer)
  • Prostate cancer

The likelihood of incontinence increases if a male pet is neutered when very young. Incontinent pets dribble urine during the day and may leak urine when they sleep at night. Most incontinent pets improve when given acupuncture and prescription drugs such as Proin, estrogens, injectable testosterone, or anti-parasympathetic medications. However, these types of medications must be used for the life of the pet.

Bone and joint problems

Neutered dogs have increases in three types of bone and joint problems: torn knee ligaments (anterior cruciate ligament or ACL), hip dysplasia, and bone cancer. ACL injuries are common in neutered dogs of every size. Hip dysplasia and bone cancer (osteosarcoma) are common only in large dogs. Some veterinarians believe bone problems occur in neutered dogs because their bones grow larger than those of intact dogs. The larger growth occurs because testosterone, which normally tells the bones to stop growing, is not present to give the stop-growth signal. It appears that larger bone size predisposes these pets to bone and joint cancer.

Cats are not prone to ACL rupture or hip dysplasia. Cats do develop bone cancer, but the effect of neutering has not been clarified.

Prostate cancer

Prostate cancer occurs more commonly in neutered dogs than in intact dogs. On the other hand, benign prostatic enlargement does not occur.

Overall health effects on neutering pets is positive

While there are serious consequences as a result of neutering, the number of pets that develop these problems is far smaller than the number of pets that develop problems if they are not neutered. In addition, many neutered pets appear happier than unaltered pets with strong sexual instincts. On the whole, neutering pets is far wiser than leaving them intact. New methods, including vaccinations and injection of hormonal blocking agents, may affect how we neuter pets in the future, and some of these methods may help prevent problems that arise from our current methods of altering.

Will my pet's behavior change after being neutered?

Male dogs and cats have two testicles that secrete the hormone testosterone. Testosterone circulates throughout the pet's body, including to the brain where it affects behavior. Under the influence of testosterone, males spray urine, fight, mark their territory, and leave home to find females. If testosterone is removed before these behaviors begin, many pets don't develop them. If these behaviors are already firmly established, neutering may not eliminate the behavior but it may decrease the behavior. For example, neutering doesn't stop aggressive biting that has already developed, but it may make it easier to teach your pet proper behavior so that aggressive biting is controlled.

Dogs that have fear aggression are not helped by neutering. In fact, many dogs with fear aggression will become more fearful if neutered. Fear aggression is different than regular aggression. A pet with aggression leans forward, carries the tail up high, and charges from the "get go." A pet with fear aggression leans away with his weight on his back legs, cowers or hides under objects, pins his ears back, and carries the tail down against its body. When people or animals ignore the signals from a fear aggressive pet and continue to approach it, the pet bites.

The nature of pets doesn't change after being neutered so that friendly, playful pets remain friendly and playful. Dogs that are good watchdogs remain good watchdogs. Dogs that like to mount females in heat continue to like to mount females in heat; however, there is no chance of an unwanted litter. Disciplining a neutered dog to stop mounting is easier than disciplining an intact dog to stop mounting.