American Bulldogs back legs, limp.

Question
Hi, I have an 8 month old American Bulldog who got up this morning and seemed to be limping a bit before his morning walk. When I took him out for a walk anyway and let him off the lead he seemed fine and started running around although he was limping slightly. I have now come back from work and he appears to be worse struggling to get back in the house through the door and having some trouble putting weight on his back legs. He has appeared to be limping slightly in the past but it went away quickly and I thought nothing of it until today now he showing signs of limping again. What do you think it could be?  

Answer
Off to the vet asap.  This could be DJD(degenerative joint disease) or hip displasia. It might be something as simple as panostitus "pano" which is often referred to as "growing pains" in large breeds of dogs.  Regardless, he needs to go to the vet for a diagnosis.  Pano often will show up as lameness in one leg and then another, and move around.  If he's having trouble in the rear consistently, he may have serious hip issues.