>I always thought exercise can cause extra wear and tear on the joints and be a problem for displasia and the like but not the heaviness of the bone.
I think exercise can strengthen bones and make them bigger & denser, but I wouldn't have thought it would be visible?
It's over exercise or prolonged/repetitive/forced exercise that can cause/contribute to problems like displasia.
> Also the breeders told them not to allow their dogs to do any serious play with each other. Now to me this means you have a very lazy dog.. For the large giant breeds i thought that 10 mins a day leaded walk while they are 4 months old was enough, thought this seems to be too much in some peoples eyes..
For
my Mastiff pup, at 4 months old 10 mins lead walking would have been too much, for other Mastiff pups it wouldn't be enough, it's best to pay attention to the pup and what they are capable of, if they seem like they could walk forever then I think it would be best to stick with the '5 minute rule'.
For fast-growing/large/giant breeds too much rough or heavy play can cause knocks or strains to the joints, lots of play is fine but when it gets rough it can cause problems.
My pup loved playing roughly with my older dog, 1 day I let the game go on too long and pup got knocked over, he fell hard on the floor and landed on his right elbow, 10 days later he could hardly walk, soon after that he was diagnosed with ED in the right elbow. I'll never know for sure if it was a coincidence that he took a hard nock to the elbow or not, but the next pup I get will not be allowed to play rough atall :(