I have a pair of 13 week old kittens. When they were younger, Bettie was much more dominant during play-fighting, but the balance seems to have tipped and now Johnny attacks her. Although it's still only play, she appears genuinely distressed when he does this. He pays no attention to her cries, which probably mean that she wants him to stop.

I took them for their boosters last week and asked how early I could get him neutered because I know that it's less intrusive than spaying, but the vet insisted that I had to wait until he was at least five-and-a-half months old. Johnny weighs more than 1.6kg and I read that male kittens can be safely neutered when they weigh even less...is that right?