I am concerned that the vet did not give you specific information on what is going on? I'd call them as ask all the questions i need to know what to do for my dog. If the vet said he needs surgery, then it is more then a pulled muscle. I am sorry that this has happened to your dog, however, if you find out that their is something serious wrong, then it is your responsibilty to care for him and make certain he recieves the propper treatment necessary. Your dog should not suffer and be in pain the rest it's life, or become perm. crippled.