I got a dogtrotter back before Christmas. I've had dogs that NEVER would run my previous mill get on that one and run it fine. I got a large, and the biggest dog I have is about 45 otc. Everything else is 40 and under. I wouldn't even contemplate a medium unless every dog I owned was 35lbs and under, and I know I would never have one bigger than that again.

You didn't have a dog run faster than 14mph because most dogs simply can't. I used to work dogs by my car, and I can count the number of dogs on one hand that could actually run 14mph for any length of time. I never had a dog that could keep up with my vehicle at 18 or 20mph. You're not working a cheetah. You're working a bulldog. I've had one dog run my mill at 15mph for a short time, and he was killing it.