Patty,
The weight of the horse comes into play in the metabolic exam. Your
weight comes into play as it causes the horse to use energy which causes
the metabolic parameters to go up. It makes no difference how much your
horse weighs unless the muscle mass produces so much energy that the
heat produced cannot be expelled. This is the reason that Arabians go
through Vet Checks faster than Thoroughbreds as their muscle mass
produecs less heat than the thoroughbreds.
Carl Meyer D.V.M.