We have a five year old male bearded collie. My wife, who walks the dog daily had been away fro six days and the dog has been walked by me (her husband) and our two children. Nothing different has happened to him but my wife returned about three hours ago and he is constantly mounting her and quite aggressively. She has showered and completely changed her clothing, in case it was the smells from where she has been and it has made no difference.
Can you advise.
Regards
Alan from Worthing, West Sussex

Sounds as if he is cross with her for leaving "the pack" and is trying to re-assert his dominance.  Dogs living together will do this too.  Might be a good idea to see a good trainer or behaviourist on how to tackle this.

Julie