Aggressive terrier mix
I adopted My now 6 yr old terrier mix from the shelter. He was surrendered by his last owner and came out with a kennel cough. He had no energy and was friendly with everyone. He was afraid in the beginning and would hide under the bed for the first 2 weeks.
He was a pandemic adopted dog so he got very few human interaction/ dog isocializing. Now he is aggressive towards others when we are present. He growls and barks as soon as the stranger gets close. I have began taking him to daycare once a week to keep him socializing with other dogs. And that has helped him a bit so far however being outside on walks it’s a different story. He chokes himself on leash attempting to run after the foreign object. I myself Have trained him to sit, stay, and pee on his puppy pad however when there is someone unknown in his sight he forgets the training. I’ve attempted to change the harness to a leash so he can reduce pulling and that has not been successful.
Any suggestions to help with aggression/ separation anxiety?