Fred is 25.8 hands tall (the standard measurement for a horse)
Fred is approximately 1.75 times wirt's height, and wirt is 4'11" or 59 inches
59 inches times 1.75 is 103.25 inches. a hand is 4 inches, so 103.25/4=fred's height. 103.25/4=25.815, rounded to 25.8
The average height for a horse is around 13-15 hands, meaning fred is significantly taller than most horses, and the closest horse breed that would still work with his design would be a Shire horse