A friend (no really I have) has a 9 month collie dog that has always been a bit wary of dogs. However he has now turned into full blown aggression towards any dog he sees. On lead he lunges and barks and snarls off lead he just goes straight into attack. Needless to say he is not allowed off lead at all now.
She is an experienced pet dog owner and has done some agility with her other dog so is not a complete novice so I think the socialising etc was done as expected.
She is devastated and is now at a loss as to what to do and has seen two behaviourists who have given conflicting advice and charged her £250 then said to call back in 6 weeks to see how things have gone One said to use a rattle bottle to wave at the dog and to be firm with him the other said he was frightened and to click every time he saw a dog but not to get too close until the dog felt happy.