hi my 4 and a half year yellow labrador seems to be having alot of problems with his paws. just recently he has been unable to go for long walks like he used to and now can only go for a bout 5 min walk before he flops down on the ground whimperin in pain and refuses to move and has to be carried home, also when in the house if he trys to get up to quick he yelps n falls down. could this bearthritus or is it this diesease ive heard of called adams diesease