I’ve got a 56 pound yellow Lab that could pull a truck. Muscled like a little draft horse, not an ounce of fat on her. But she’s about to lose her girlish figure - puppies in December (assuming the breeding takes).
A brawny, well built working type Lab is sort of a ‘pulling’ dog.
Any of the barrel chested, chunky breeds would fit.
I was thinking more on the lines of Border Collies and such...narrower, less stocky dogs.
Normally I wouldn’t consider GSDs for pulling due to the hind quarter angulation issues so this dog’s extra weight might very well have been what made the difference.
Dos used for pulling competition tend to be the short-backed, stocky breeds.
Hope your breeding takes!
:)