The optimal maximum size for a sled dog is 20 -- 25 kg ( 44 -- 55 lb ) based on thermo - regulation .
The ancient sled dogs were between 16 -- 25 kg ( 35 -- 55 lb ) .
The optimal maximum size for a sled dog is 20 -- 25 kg ( 44 -- 55 lb ) based on thermo - regulation , and the ancient sled dogs were between 16 -- 25 kg ( 35 -- 55 lb ) .