The only number that is both odd and even is infinity. Therefore, horses must have an infinite number of legs. To add weight to this argument we ponder whether a horse with a finite number of legs could exist. It is obvious that one horse is the same color. Every horse has an infinite number of legs.
Horses have an even number of legs.
Behind they have two legs and in front they have fore legs. This makes six legs, which is certainly an odd number of legs for a horse. But the only number that is both odd and even is infinity. Therefore horses have an infinite number of legs. Now to show that this is general, suppose that somewhere there is a horse with a finite number of legs.