Shoulder flexions. From the horse's left side, stand close to the horse, facing to the rear, as though you were going to pick the hoof. Pick up the foot, placing one hand just above the hoof and the other hand in front of and above the knee. Slowly bring the leg backward until it is at a 90-degree angle. Hold this position for 10 to 15 seconds, then return the foot slowly and gently to its resting position. This stretch also can be repeated two or three times; then switch to the horse's right side to perform the same stretches.
Passive tail/back stretches. Since humans don't have tails, we generally aren't conscious of how the tail and the back are tied together via the vertebrae and spinal column. Pulling on the tail stretches not only the tail, but also the back, and it can give you a good indication of how your horse's back is feeling. A horse with a sore back and/or nerve impingement will clamp his tail and resist any upward tail movement by his handler, so take note of reactions as you perform these stretches.
Tail rotations. Stand close behind or to the side of your horse's rear end, but be wary of kicks or backward steps. Hold the dock of the tail with both hands and lift up slightly. Make small circular motions with the tail, rotating in both directions for three to five rotations. Stay calm and relaxed and work very slowly. Soon your horse will love this stretch.
One caution: While this sounds simple, many horses will clamp down their tails and refuse to budge. You can get your horse to relax his tail by rubbing or tickling the hairless underside at the base of the tail for a moment with your fingers. If he reacts violently to having you try to lift his tail, you may want to consult an equine body specialist or healthcare professional.
Tail pulls. Stand about an arm's length behind your horse's rear end. Because this is a very dangerous position, you must be aware at all times of the horse's reactions to your stretches. Be prepared to move out of danger immediately if necessary. Grasp the tail just above the end of the tail bone and visually align the tail with the horse's spine. Slowly and gently pull straight out from your horse's back, hold for a few seconds, and then slowly release. A sudden release of this pressure on the tail is uncomfortable for a horse's back, so go slowly. You can work up to holding this stretch for as long as two minutes, again releasing very slowly, a little pressure at a time.
When doing tail pulls, heed this caution: Because this is likely the most dangerous position for you to put yourself in, don't take your eyes off of your horse's demeanor and reaction as you perform this stretch. If your horse shows any signs of anger, fear, or distress, forego this stretch until you've had more time to prepare him mentally and physically.
Remember, stretching should be physically and mentally beneficial. Done in a kind, gentle, and effective way, it's a routine your horse will soon come to relish.
