They're so clever when it comes to getting out. I had to try 3 different harnesses on my Chelsea before I found one she couldn't slip out of.

This is the third harness! What one worked for you? How do you judge between being too tight and too loose?

It was a while ago, so I can't remember the brand. I do remember that it had straps on both the front and back of all the legs. And err on the side of it being tight.