Which horse breed can be no taller than 46 in order to registered?

The horse breed that can be no taller than 46 inches to be registered is the American Miniature Horse.

This breed is specifically defined by its small stature, with a maximum height of 34 inches for stallions and 38 inches for mares. However, they can be no taller than 46 inches to be registered with the American Miniature Horse Association (AMHA).