So very very sorry to read your experience. My heart goes out to you. My dachshund also is a muscular little fellow...and at first jumped up and down from furniture and steps. Then he started getting back spasms. It is awful to see him in such pain. For now the vet has us give him pain killers, muscle relaxers and plenty of rest. We don't let him jump.....at least if we can catch him before he does...and lift him up and down stairs if he seems to be having a hard time. We really want to avoid surgery because of stories like yours, and others similar. We just hope he won't end up in a little cart, but we'll love him even if he does. Thanks for sharing.