Hill dragon

The hill dragon was a roughly elephant-sized Safeholdian dragon commonly used as a draft animal by humans. Despite their size, they were capable of rapid, sustained movement. 

Comparison with Earth Draft Animals
A fully adult male hill dragon weighed under fifteen thousand pounds, about ten percent more than an African bull elephant, and its digestive processes were far more efficient than an elephant’s. Most of Old Earth’s other ruminants’ digestion had been fifty percent more efficient than an elephant’s, but the hill dragon’s was over seventy percent more efficient. Hill Dragons were known to eat almost any form of vegetable matter.

Hill Dragons with their six limbs, as opposed to the elephant’s four, were also capable of higher sustained speeds in poor terrain and could carry proportionately heavier loads. With a properly designed pack frame, a hill dragon could carry up to thirty percent of its body weight, which compared favorably to a horse’s twenty percent, far less an elephant’s capacity of barely ten percent. (MTAT)