The general consensus among dog care experts is that it is advisable to neuter older dogs to protect them from age-related diseases. Adults dogs that are overweight have a small risk of experiencing post-operative complications; however, neutering operations on older dogs are considered a safe and effective procedure.
According to the ASPCA, adult male dogs benefit greatly by undergoing neutering. As male dogs age, they are susceptible to serious health problems such as an enlarged prostate or testicular cancer. An enlarged prostate gland interferes with urination just as it does in men. Older dogs may develop prostate or testicular cancer, which are serious health risks. These health issues are less likely to occur if the pet is neutered.
The Sanctuary for Senior Dogs reports that behavioral problems in older dogs may be curtailed or eliminated by neutering. Dogs that have not been neutered have a high level of testosterone in their system. Testosterone is a natural hormone in the body that sometimes leads to aggressive behavior. There is some indication that neutering adult dogs alleviates problems with aggression. However, this is not considered a complete solution for aggressive behavior.
Other problems that neutering may fix are excessive urination to mark territory, indiscriminate mounting of people, objects and other dogs, and roaming due to being in heat.