Two days ago we went out and accidentally left Coco and Tilla out in the yard for hours.  They were eager to come in.  Tilla was limping on the foot he had knee surgery.  It gets sore and hurts him too much if he runs on it too much.  So he does not put any weight on it.  I checked his leg to make sure there was no apparent injury.  Today he is walking on it and only favoring slightly.  I am still going to call the vet’s office just to make sure that only happens occasionally and his knee is fine.