Hi, I have a 3 year old female lab/springer mix (she's 3/4 lab) named Jodie. We socialised her well when she was a puppy, and has always been a incredibly submissive dog to other dogs and people (she's wary of other people without a dog, barks and growls but soon realises they're friendly and is happy to meet them - others with dogs she likes to greet rather than the dogs themselves!). When walking, if another owner has a ball, then she used to half chase it and give up - since it was the other dogs ball etc. However, she's started becoming possessive, even attacking when dogs come up to her when she has a ball (hers, or another's!) or a stick. She had a ball the other evening, another dog came up to her to say hello and she attacked it. This is very strange behaviour for her! I'm wondering what could have occurred for this strange change in her behaviour. Anyone got any ideas? Thanks.