An anti-choke attachment for a horse for preventing internal blockage of the horse's nasopharynx or other blockage of the horse's breathing when the horse is running or vigorously exercising. The attachment temporarily locks the horse's head against tilting downwardly or swinging sidewise. The attachment comprises a rigid plate having a lower part shaped to fit against a horse's neck and an upper part shaped to fit beneath the rear portion of the horse's jaw. An elongated, relatively thick, resilient pad arranged on the upper part is arranged to fit closely within the intermandibulary space region along the rear of the horse's head so as to prevent downward tilting and sidewise swinging of the head relative to the neck which both prevents partial blockage of the nasopharynx and helps maintain driver control of the horse.