The horse is just playing dead, T-boy. Horses are smarter than the average cowboy, so as soon as the shooting starts they do the smart thing and either run away or feign death, providing their rider is incapacitated. The dumb cowpoke on the other hand runs toward the sound of gunfire, and never plays dead until he actually is dead.

This results in a higher survival rate for horses, which is a fine example of natural selection at its very best, ensuring the continuance of the superior species.

- LH