Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Just didn't work for my dog

I tried several sizes and none seem to work well for my dog. He has a broad chest. He's a mini pin/chi mix so not sure what is going on, but it appears to fit but when we go on walks and he gets at all excited, tries to run, even go # 2, after it seems his legs get caught in the harness. It's hard to describe in words, but it didn't work for him.