Neutering your Male Dog

January 1, 2001 (published) | February 9, 2021 (revised)
Photo courtesy of Depositphotos

Why Should I Neuter my Dog?

Aside from helping control the current overpopulation of dogs, neutering a pet dog generally makes for a healthier dog and a better pet. Neutered dogs tend to live longer and have fewer behavior problems (see below). They are less likely to be relinquished to the shelter and do not contribute to over-crowding in community animal shelters with their off-spring. The local government is more interested in having fewer roaming dogs that could be dangerous and having less burden on the animal services budget. Pet owners are more interested in having a well-behaved and long-lived family pet.

What are the Health Benefits to the Dog? 

There are several health benefits to neutering. One of the most important concerns the prostate gland, which under the influence of testosterone will gradually enlarge over the course of the dog’s life. By age five years, it is usually significantly enlarged in an unneutered male dog. As the dog continues to age, his prostate is likely to become uncomfortable, possibly being large enough to interfere with defecation. The prostate under the influence of testosterone is also predisposed to infection, which is almost impossible to clear up without neutering. Neutering causes the prostate to shrink into insignificance, thus preventing both prostatitis as well as the uncomfortable benign hyperplasia (enlargement) that occurs with aging. It is often erroneously held that neutering prevents prostate cancer but this is not true; neuter benefits on the prostate are about preventing enlargement and infection.

Other health benefits of neutering include the prevention of certain types of hernias and tumors of the testicles and anus. Excessive preputial discharge is also reduced by neutering.

What Behavioral Changes Can be Expected After Neutering?

Numerous studies on the behavioral effects of neutering have been performed evaluating playfulness, fear of strangers, territorial aggression, mounting, urine-marking, roaming and other behaviors. The behaviors that are most consistently altered after neutering are inappropriate mounting, urine marking, and fighting. These behaviors were significantly reduced or completely eliminated in 50-60 percent of male dogs after neutering. Most pet owners look forward to curtailing these actions and thereby improving their relationship with the dog.

What Exactly is Done Surgically?

An incision is made, generally just forward from the scrotum. The testicles are removed through this incision. The stalks are tied off and cut. Castration is achieved. If the testicles are not removed, the desirable benefits listed above cannot be realized. The skin incision may or may not have stitches.

What Can I Expect upon Discharge from the Hospital?

The scrotum is often swollen in the first few days after surgery, leading some people to wonder if the procedure was really performed. If the dog is immature at the time of neutering, the empty scrotum will flatten out as he grows. If he is mature at the time of neuter, the empty scrotum will remain as a flap of skin. Sometimes the incision is mildly bruised. Most male dogs are eager to play by the day after surgery but, to keep the incision intact, it is best to restrict the dog from boisterous activity.

Elton is an intact viszla. Photo by Adrienne Freyer, used with permission.

At what Age Can Neutering be Performed?

Male dogs can be neutered at just about any age, although the traditional age is still before puberty at 6-9 months old. There is some controversy regarding when the best age for neutering should be: after puberty, traditional age, or "early" which can mean any age from 8 weeks up to 6 months.  Shelters have had problems with adopters of young puppies failing to return for neutering at the traditional age; a common solution is to neuter prior to adoption to preclude the pup's ability to contribute to pet overpopulation himself when he is older. It turns out there may be negative ramifications to this depending on the dog's breed.

Long bones continue to grow for a longer period of time in dogs neutered before puberty, making for a taller adult dog. There can be joint problems associated with this, especially in larger breeds. Not all breeds, even large breeds, seem to have negative consequences when it comes to neutering before one year of age, so it is best to consult your veterinarian about when to neuter your individual male dog.

Senior dogs can also benefit from neutering. A diseased, enlarged prostate will still shrink down to a comfortable size even in an older dog. The neuter is a relatively simple low-risk surgery, which means that even an older dog can still benefit.

Will he Become Over-Weight or Lethargic?

Metabolism changes with neutering in such a way that there is a moderate risk of becoming overweight after neutering. The dog owner should be prepared to make adjustments in diet or exercise if the dog seems to be gaining too much weight.

Will he Still be Interested in Females?

His interest will be reduced but if he is around a female dog in heat, he will become aroused by her. Mounting behavior often has roots in the expression of dominance and may be expressed by a neutered male in a variety of circumstances that are not motivated by sexuality.

What if a Dog Has an Undescended Testicle?

Undescended testicles have an increased tendency to grow tumors. They may also twist on their stalks and cause life-threatening inflammation. For these reasons, neutering is recommended for dogs with undescended testicles. This procedure is more complicated than a routine neuter; the missing testicle can be under the skin along the path upon which it should have descended to the scrotum, or it may be even inside the abdomen. Some exploration may be needed to find it, thus there is often an incision for each testicle. The retained testicle is sterile and under-developed. If there is one descended testicle, the dog will be able to breed but since retaining a testicle is a hereditary trait, it is important that the male dog not be bred before he is neutered. It is not a good idea to pass on the retained testicle trait.

A neutered dog. Illustration by MarVistaVet

What are the Negative Aspects of Neutering?

This turns out to be a more complicated subject to study than one might think. The issues that are typically studied are orthopedic/joint related problems and different types of cancers and whether neutering a male dog truly changes the incidences of these. The Hoffman study of 2013 looked at over 70,000 canine medical records and found that neutering increases a dog's lifespan by 14 percent. They found that neutered dogs were less likely to die of infectious diseases, degenerative diseases or trauma but were more likely to die of cancer or immune-mediated disease than their unneutered cohorts. Upon scrutinizing different cancers, incidences are still low. For example, the risk of developing prostate cancer is several times higher in neutered dogs vs. unneutered dogs but still less than one percent in both groups. Cancer development is more about environmental exposures and heredity/breed predispositions than about testosterone, so it has been difficult to draw conclusions.

With regard to hip dysplasia and cruciate ligament rupture, probably the most common joint problems of dogs, body condition/obesity, general size of the dog, and genetics are likely to be the major risk factors but there does seem to be an increased risk of these issues in dogs neutered before puberty when their bones are still growing and conformation is not set.

Is Neutering Legally Required?

In some areas, neutering may be required as municipalities attempt to prevent pet overpopulation. Check with your local city or county officials.

For example, in Los Angeles exemptions to the spay/neuter requirement include any of the following:

  • The dog is a member of a breed approved and registered with a registry or association approved by the Animal Services Commission, and does or will actively show or compete.  
  • The dog has earned or is in the process of earning a specific title (i.e., agility, herding).
  • The dog is used as or is in training to be a guide, signal or service dog.
  • The dog is trained or in training, for use in law enforcement, military or rescue activities.   
  • A letter from a licensed veterinarian certifies that the animal should be temporarily or permanently deferred due to age or health. 
  • The owner has a valid breeding permit, issued to the owner, pursuant to existing city ordinance.

If any of these conditions are met, the owner must apply for an "intact dog license" from the city. This special license is much more expensive than a regular dog license, which is what neutered dogs get.

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