When my shihtzu, Emma, goes into heat, Kobe (male, neutered shihtzu) will mount Emma and they actually get stuck. The first time this happened I called my vet thinking maybe they botched his neutering job (which would have explained why i can't get him to stop marking). They probably thought I was crazy, but they said that is normal in some dogs.
I think you can get her spayed while in heat. My sister had hers spayed during her first heat. I don't know much about it, but my sister never had any problem.
joan |