My dog has been in kennels for a year and needs to strengthen in the rear even though he has no problem standing up on his hand legs which we try to discourage. any suggestions. I thought of swimming but do not want him to build up the front and the stuff they put in the water effects the coat.

Most of the powering for swimming actually drives from the rear. I watch mine swimming in clear water and the power is amazing. i wouldn't suggest a tredmill though. A good hydro pool owner will at least rinse & probably shampoo them afterwards.

Some treadmills have incline & decline so one way will build up the front & the other the back.

Building up his normal walks such strenghthen him up naturaly.