Agressive Mastiff Mix

by Stephanie
(Memphis, TN)

I took in a stray puppy about 4 months ago. He had been beaten and was fearful of people. In the time I have had him he has bonded well with me and my other dog, but is still very fearful/agressive towards some dogs and strangers. At 8 months he is 85 lbs, so that does not help people react to his agressiveness in a rational manner.

I cannot find a single "trigger" that they have in common. There are times he is amazingly loving and playful to strangers, and others I am afraid he is going to seriously hurt someone.

I can take food/bones/toys out of his mouth (I always give them back with praise and extra petting), push him off the couch, play tug-of-war, any number of things and there is never a show of agression towards me. He loves my older rottie female and will play with her for hours.

He is loving with other people, and then the next person he tries to attack - friends visiting, the vet, people who walk near him, other dogs on leashes, anything. There is no consistency (male/female/glasses/hat) no obvious trigger. The attack is out of fear, you can see it in his stance, but I do not know what he is afraid of and why some are OK and others are not.

I don't know how to desensitize when I don't know what to target, and taking him in public where people react in fear does not help.

Any ideas?