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. In age, it is likely to become uncomfortable, possibly being large enough to interfere w/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. 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.
The only behavior changes that are observed after neutering relate to behaviors influenced by male hormones. Playfulness, friendliness, and socialization with humans are not changed. The behaviors that change are far less desirable. The interest in roaming is eliminated in 90 percent of neutered dogs. Aggressive behavior against other male dogs is eliminated in 60 percent of neutered dogs. Urine marking is eliminated in 50 percent of neutered male dogs. Inappropriate mounting is eliminated in 70 percent of neutered dogs.
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 achieved. The skin incision may or may not have stitches.
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 but this is not unduly sore for the dog and pain relief is almost never necessary post neuter. 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.
Neutering can be performed at any age over age 8 weeks. Dogs neutered before puberty (generally age 6 months) tend to grow a bit bigger than dogs neutered after puberty (testosterone is involved in causing bones to stop growing so without testosterone the bones stop growing later). Neutering can also be performed in the geriatric patient should the prostate gland become enlarged and the best medical decision be to shrink it. In this event, preoperative blood work and other diagnostics relevant to anesthetizing an older patient would be recommended. The traditional age for neutering is around 6 months of age and many veterinarians still recommend neutering at this age. The benefits of neutering (both health and behavioral) can still be obtained regardless of the age at which neutering is performed.
Activity level and appetite do not change with neutering. A male dog should not gain weight or become less interested in activity post neuter.
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.
Undescended testicles have an increased tendency to grow tumors over descended testicles. 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 it should have descended to the scrotum or it may be 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, this one will be fertile but since retaining a testicle is a hereditary trait, it is important that the male dog not be bred before he is neutered.