First finish drawing the horse's face. Draw the eye - basically a circle with a right-angled roof over it. Add the mouth - almost a straight line, with a little downturn at the end. The nostril is a simple curved line.
Finish the hooves by drawing a line to 'cut off' the back corner of the triangles. Draw a line near the top of each triangle to form the top of each hoof.
Lastly draw the mane and tail. You can make the mane and tail long and sweeping, or make them neatly trimmed for a thoroughbred or show pony.