The big metal balls that tied to a chain are fairly scary creatures and it seems to make no sense at all that they make a barking sound. They have been in lots of Mario and Mario Kart games and I have always wondered why they make a barking sound. It seems like it might have been a mistake made a long time ago that has stuck or something?
I think it was down to the games creator. He had an experience as a child where a dog tried to attack him but was held back by the chain. This is what the chain chomps were based off of and also why they make a barking sound