I have a 9 year old Newf. He is a very good and well mannered dog. He does one strange thing. When we feed him, he growls and bites his tail. Never a person or another dog. Does anyone know why he would do this? It is comocal, but I tell him to stop because he has on occasion hurt himself.

Some dogs who perform this behaviour have learnt it as young dogs - have you had him since he was a very young pup?