This is the 51st ''Threshold Picture Guide'' where Perry Wood gives much needed advice on common riding problems. It gives practical tips on how to improve your horse's behaviour under saddle, making him safer to ride and a pleasure to own. Subjects covered include bucking, rearing, head-tossing, shying, jogging, bolting, napping, refusing to jump, nose poking, difficult to mount, hard-mouthed, overexcited and inattentive to the rider.