The breeder suggested waiting for 2 years to allow him to continue growing. I have heard a few others on here that were told the same thing, at least about males. I have never owned a female dog (too afraid!) for that very reason LOL I did get my pekingese fixed after he was older with no issues. The problem of course with waiting are raging hormones !!!!
Luckily Herman hasnt been around any cats. I dont plan to get him fixed until he's around 2 years or so...But his breeder told me she didnt notice any difference in the amount of humping when they were fixed either. He humps me all the time, but usually when I'm under his favorite blanket - he seems to like to hump to soft/fuzzy things like blankies, his bed pillow and his toy fuzzy turtle LOL