Welcome! My name is***** am a UC Davis graduate, and currently, a Medical Director of a veterinary hospital.
Do you mean sterility caused by a dog being neutered, or sterility caused by another problem?
If you are referring to the neuter surgery, this is a great question and highly controversial.
For most dogs, especially the small breeds, there are very few other health concerns. Some would argue it can predispose to weight gain, although it is easily argued that is more likely due to dogs over eating and being too sedentary in the city life.
However, for large or giant breed dogs, it is believed it could alter their growth
and possibly predispose to other joint or bone
problems. That is why some vets are now encouraging that large or giant breed dogs not get neutered at 6 months of age, but perhaps, wait until at least 12-16 months to do the surgery. But, not all vets agree on this issue.
This question becomes even more complicated when talking about female dogs. When a female dog is spayed BEFORE their first heat cycle
, their chances for getting mammary cancer are the least. This is very significant since we diagnose a lot of mammary cancer in older female dogs. But! Early spay surgery may also predispose to other issues like other forms of cancer that appear to be less common or other joint issues.
So, its a very difficult question. For a small breed MALE dog, I strongly encourage the neuter surgery at roughly 6 months of age.