Instruct: Classify a review into positive or negative sentiment.
Query: Sorry, does not work on all dogs.

DID NOT WORK ON MY COCKER SPANIEL AT ALL!!!!!!! However it did work on my Chihuahua, but I got his thing for only my Spaniel (my Chihuahua is trained), so to me, it's useless. It did not even make a single impression on him. And trust me, his ears are fine. I got so frustrated that I even used it 1 inch from his ear, and absolutely nothing happened! He even tried to chew it! Well the box did say that it worked on most dogs, so I can't be too upset. Make sure that if you get this product, that it comes with a good return policy just in case it does not work on your dog.