we got jack in february. he was approximately a year old then. he was incredibly sweet and got along with everyone. then around june i guess he started feeling a little more settled and even a little territorial. while on a walk he lunged and snarled at a neighbor and even nipped him!! i chalked it up to him being startled or "sensing" something about the neighbor. well since then he snaps at probably 8 out of 10 people on our walks. and when i say snap i mean full blown kujo-like snarling,lunging,scariness. we use the gentle leader. it doesn't seem to help. he also goes crazy at people who pass by the apartment when he's on the balcony. i try to have him watch me when we are on a walk and someone passes by. i try to distract him with a treat or a toy. this doesn't seem to help. i don't know what to do. any advice is welcome.

Seems he's become overly protective and guarding HIS things. My suggestion is to first get this guy into some obedience training. I would first start with a group setting, but ask if you can just bring him to one class to see how he interacts with the other dogs/people. If he's calm, enroll him in the class....if not, he will need a one on one training class in which case I would opt for help with a behaviorist/trainer. Be sure to use gentle, positive reinforcement training methods since he already has some aggressive issues.

Also have him fixed. Ever hear of a muzzle? You know he is doing this and you still take him around people? Are you waiting for a little child to walk up to the doggie and get mauled???

[wishbone]

Does he acting like that since June? Hope he did fully developed that attitude, show him you're the boss. Spray him with water whenever he acts aggressively towards other. Obedience training could help a lot. Also sudden change of behavior is indication of health issue, let the vet take a close look at him.

[Piti Longstalking]

Originally Posted by wishbone

Spray him with water whenever he acts aggressively towards other.

You may want to read up on classical conditioning before recommending this.

To the OP, a vet check is definitely in order. I'd have this dog's thyroid checked. Regardless a strong emphasis on NILIF in your home would be my next suggestion. I would not recommend an obedience class at this time as an obedience class is not for behavioral issues, and such a class could exacerbate your problems, not help it. It may be better for you to speak with a certified behaviorist for one on one time.

Good luck!