Why did my dog bite my Mum and what can/should I do about it?

your dog is becoming an adult and those playful puppy nips are now becoming serious bits. she should have been stopped from doing it as a puppy. she is crossed with two large and potentially aggressive breeds. as such she would probably have benefited from an owner who is an experienced dog handler. lunging at other dogs can be stopped by using a nose harness and she should be muzzled while out. as for biting your mum this is unacceptable. next time it could be much worse or what if it had been a child? your dog needs to see an animal behavioural therapist, soon, before something really bad happens