dogs bowel movements

Question
our female shepard mix yips in pain when having a bowel movement,also turns her head towards her behind and seems to have no control.
the vet has checked her rectum,anal spincers,spine and taken exrays but can find nothing wrong. he gave her antibiodics as precaution but that didn't change anything. all this started when she was about three years of age and has been ongoing


Answer
I would try adding some fiber to her diet to see if that helps as well as giving her MSM and Omega 3 Fatty Acids...about 1000 mg of each twice a day to see if that may help reduce any inflammation.  If it continues beyond this, then pain medication such as a non-steroidal anti-inflammatory could be tried or something like Amitriptyline.  I would recommend having her hips x-rayed as well as it is very likely that she may have some hip dysplasia.