How old should a dog be when it is neutered?

Six to nine months is the traditional age before neutering is acceptable, although eight weeks is sufficient if the puppy is in good health. Neutering older dogs carries a risk of medical complications if the animal is overweight.

Besides the benefit of preventing unwanted pregnancies in domestic dogs, neutering reduces the risks of prostate-related maladies and testicular cancer. In addition, certain hormone-related behaviors are reduced if the animal is neutered. These include urine marking, roaming, aggression, mounting and social problems with other dogs. It is best to neuter a dog at the recommended age; otherwise, it is possible the animal will maintain some of these behaviors if it is old enough to have displayed them.