On the Cavalry Commander (1.15-1.16)

A horse’s stones should not be big: but it is impossible to observe this in a colt.

As for the parts below, the hocks, shin bones, fetlocks and hoofs, what we have said about the corresponding parts in the forelegs applies to these also.

I want also to explain how one is least likely to be disappointed in the matter of size. The colt that is longest in the shanks at the time he is foaled makes the biggest horse.[*] For in all quadrupeds the shanks increase but little in size as time goes on, whereas the rest of the body grows to them, so as to be in the right proportion.