It should fit a boxer, We have 4 dogs 3 are over 50lbs and it was tight and then our little guy is 10lbs so to big for him. It did go on our Pit but it was tight.I hope this helps and the leash would work with any dog :)
Hi I added some pics of our girl Buffy wearing it. She is over 60 lbs. and her girth is 29-30 around. I hope this helps, this is the largest it goes but can be made shorter.Sorry my other dogs are bigger than Buffy and our Chihuahua is only around 10 lbs. so he is to small. thanks.