I met a lovely BC puppy last year. Sociable, doing really well with his training an absolute joy to his owner. A while later his owner got another male pup, equally as handsome. Turns out he was the son of her older dog. She had used him at stud just before his first birthday. Whilst she was concentrating on training the pup the older dog became increasingly troublesome, particularly around other dogs and his relationship with his son is very rocky.
It could be just his age, the fact that another dog joined the household and he wasn't getting the attention, who knows, but she does regret letting him mate with her friend's bitch and believes it to be a contributary factor to his behaviour.
