Suddenly aggressive 2 yr old Welsh/border collie cross
My male dog has been well trained attended puppy classes unlike our 4 yr old BC who never went to any training. He was brilliant until about 6 months ago. Began growling at other dogs when out deep drowns pulling leash to get to them. He doesn't do this to our other dog, he is the same with people even people who knew as a good little pup. My sister found his aggressive barking and growling at her last week really distressing. He is fine with us 2 adults in the home and we live in countryside. I won't take him for a walk now as he is too aggressive and frightens people.
I believe it's stress related anxious behaviour