Other than population control, there are several behavioral and medical reasons to castrate (remove the testicles from) male dogs. Most of the medical and behavioral conditions that are treated, at least in part, by castration are caused by the male hormone testosterone, which is produced within the testicles. That is the major reason vasectomies have never been popular or useful in veterinary medicine. A vasectomy eliminates successful breeding, but it does not reduce any of the undesirable problems of the intact male, since it does not affect testosterone production or its distribution throughout the rest of the dog's body.
Behavioral Benefits of Neutering
There are several important behavioral benefits of neutering. Some of the most important benefits include decreased aggression, roaming, inappropriate mounting, and urine marking.
Decreased Aggression
One of the most important behavioral advantages of castration is that as adults, these dogs will tend to be less aggressive both toward other male dogs and also people. The androgen (male) hormones, of which testosterone is the most important, are responsible for the development of many behavioral patterns. When young puppies are mounting their 7 and 8-week old litter mates, this is because of androgen surges in their bodies. The same is true with aggressive behavior. Some medications that have androgenic hormonal activity often cause increased aggression (an example would be the birth control medication, Cheque Drops, which contains one of these androgen-type chemicals). The degree castration has on suppressing aggression varies between animals and the age at which it is done. Its effect is greatest if it is done before one year of age.
Decreased Roaming
A second behavioral advantage of neutering is that these dogs will be less likely to roam when they smell a female in heat. Male dogs can smell females in heat through pheromones. These are airborne chemical attractants that are liberated from the female when she is cycling. They travel through the air for great distances. Pheromones are very effective stimuli. Pheromones can be sensed by a male dog miles away from the physical location of a female in heat. If dogs are neutered at an early age, they are less likely to sense or respond to pheromones and tend to stay home.
Decreased Inappropriate Mounting
Another benefit of castration is decreased inappropriate mounting behavior. Mounting can be both a sexual behavior as well as a display of dominance. Neutered males tend to not mount as a sexual behavior because their testosterone levels are much lower than an intact male dog.
Decreased Urine Marking
Urine marking can be a real problem in intact male dogs. Neutering has the benefit of reducing urine marking behavior.
Medical Benefits of Neutering
The medical advantages are numerous and even more significant. Again, all are caused by the effects of testosterone on the body or are physical problems that arise within the testicles themselves. Here again, a vasectomy would not serve any real or meaningful purpose.
No Testicular Tumors
There are several different tumor types, both benign and malignant, that arise within the testicles. As with most cancers, these usually are not noted until the animal reaches 5 or more years of age. Therefore, these would not be a problem in those individuals castrated at the recommended age.
Improved Genetics
Males with known hereditary or genetic conditions should be neutered to prevent certain conditions from being passed on to the offspring. Responsible pet parents must do all that is possible to prevent th spread or continuation of heritable conditions. Dogs with certain kinds of hernias, hip dysplasia, and epilepsy should not be bred.
Fewer Perianal Hernias
A hernia is a protrusion of an organ or parts of an organ or other structure through the wall of a cavity that normally contains it. Perianal hernias occur when the colon, urinary bladder, prostate, or fat protrude from the abdominal cavity, through the muscular wall by the anus and then lie just under the skin. This type of hernia is far more common in older, unneutered male dogs. The levels of testosterone and other hormones appear to relax or weaken the group of muscles near the anus. When the animal then strains to defecate or urinate, the weakened muscles break down and the abdominal organs and fat bulge out under the skin. In shorthaired breeds, this large bulge is noted by the owner almost immediately, but in longhaired breeds, the problem may go on for months before anyone realizes there is an abnormality. Left untreated, these organs may become damaged, unable to function or even die from loss of blood supply. Additionally, because of the displacement of organs into this area, the dog may not be able to defecate or urinate correctly or completely and may become constipated or have urinary incontinence (dribble urine).
Fewer Perianal Tumors
There are tumors whose growth is stimulated by testosterone. These occur near the anus and are called perianal adenomas (benign) or perianal adenocarcinomas (malignant). As with the hernias, these usually do not occur until the dog is at least 7-years old. They require surgical treatment and should be caught early in their development to prevent recurrence. These tumors and the above hernia are very, very rare in those individuals castrated at 7 to 8-months of age.
Fewer Prostate Problems
The most common medical problems eliminated in dogs neutered at an early age are those involving the prostate. Over 80% of all unneutered male dogs develop prostate disease. Prostate conditions such as benign enlargement, cysts, and infection are all related to the presence of testosterone.
Is Early Neutering Safe?
In the United States, most dogs are neutered between 6 and 9 months of age. Many animal shelters and veterinarians are starting to neuter male animals at a younger age, even 8-14 weeks of age. There is some controversy regarding the best age to neuter a dog. The younger a puppy is when he is neutered, the longer his long bones will grow. This will result in an adult dog with a tall stature. This can have adverse effects on the musculoskeletal system. On the other hand, young dogs or puppies tend to recover more quickly from surgery and experience fewer surgical complications.
Neutering has many benefits, including population control, fewer behavioral issues, and fewer medical problems that are the result of testosterone. Whether your dog is a puppy, adult, or a senior dog, neutering is recommended for the health and well-being of your pet.