An animal that has extremely straight hind legs is best described as being:

When an animal has extremely straight hind legs, it is best described as being post-legged. This term refers to a conformation issue where the hocks – the joints in the hind legs – are positioned too far behind the body, resulting in legs that appear overly straight. This condition can lead to a number of performance issues, particularly in livestock, as it may affect the animal’s ability to move efficiently and could lead to stress on joints and tendons.

The other terms describe different leg conformation issues. Although understanding them is useful, they do not apply to the case of straight hind legs. Cut-legged refers to a different conformation that often indicates a more angled leg. Cow-hocked describes legs that point inward and touch at the hocks while bow-legged refers to legs that curve outward. Therefore, when identifying straight hind legs, post-legged is the most accurate description.