We have three Yorkshire Terriers, two male and one female. Most of the time, they get along fine, playing together, sleeping in the same bed, etc. However, once every day or two the larger-but-younger (1-year-old) male will attack the smaller (2-year-old) male. There haven't been any serious injuries, but we have found some small tooth marks on the smaller dog's ear.

The larger male is generally a very obedient and sweet-tempered animal. The larger dog has not been neutered; the smaller one is neutered. Both dogs get along fine with the female. We haven't noticed the smaller dog doing anything to provoke the attacks.

The smaller dog has started to avoid the larger dog, and will often cower in the corner. I'm not really worried about a serious injury happening, but I do want the smaller dog to feel safer and happier.

Anyone have any tips for helping the dogs to get along better?