A saddle fit to an atrophied back will block those muscles from developing further & his gaits will not only suffer, but he will be in discomfort. A vet may indicate that the horse is a sound horse, but that doesn’t mean the horse is ready to carry a rider. You would be far further ahead to wait, do absolutely Now ride or saddled work, and rehab the back properly. Then, when the back is better, you’ll have better luck finding a saddle that fits. ay indicate that the horse is a sound horse, but that doesn’t mean the horse is ready to carry a rider. You would be far further ahead to wait, do absolutely Now ride or saddled work, and rehab the back properly. Then, when the back is better, you’ll have better luck finding a saddle that fits.