walking after Bowel problem

Question
Hii have a golden retriever  he is  13  When he goes to have a bowel nmovement  once in a while its  seems hard for him to go  but  the real thing is  after he s so called done he cant walk I literally have to pick him up and  carry him  he has a very hard time to move  his back legs   I wonder if anyone  can maybe  help me  why he has this problem  Its  not  all the time  neither  Is it  GAS  PROBLEMS?? BLOATING PROBLEMS??

Answer
He may be getting old, losing muscle tone and arthritis setting in.  why not have the vet take a look and maybe prescribe something of his arthritis.  A prescription for Metacam has bought our 15 year old Lab another 6 months, but now she mayhave a liver tumor.