Swayback — technically called “lordosis” — is the deeply sagging top line that develops in some older horses. It’s caused by weakness and laxity/stretching of the supporting ligaments along the spine, often with weakness and loss of bulk/tone in the top line musculature.
To a large extent, lordosis is an aging change caused by the forces of gravity on the spine over the years. The weight of the horse’s chest and abdominal contents constantly pulls the back down. It’s common in aged broodmares, who have had the added weight of a pregnancy stressing the back. Letting the horse get too fat obviously contributes to strain on the back. Similarly, carrying a heavy rider for many years might increase risk, but this has not been specifically studied.
Conformation also plays a role. Horses with overly long backs are more prone to back problems in general, including swayback. Horses with high-set necks and a high head carriage may be at higher risk because this way of moving tends to hollow the back.
Finally, age-related weakness in ligamentous tissues, together with loss of muscular tone and bulk related to aging, lack of exercise and some diseases (e.g. Cushing’s disease) can eventually lead to a poor ability to fight gravity.
There’s really no way to accurately predict which horses will become swaybacked, but the more risk factors, including multiple pregnancies, age, long back, the greater the likelihood. Complete prevention may not be possible, but horses that remain active into their older years and are kept at a normal weight (not fat) are less likely to develop lordosis.
If you can’t always ride your older horse, at least consider trying to keep to a schedule of light regular groundwork, including exercises for the back. If you see lordosis developing at the same time as a big belly, and loss of muscle size and tone elsewhere on the body, ask your veterinarian if testing for Cushing’s disease might be in order. The muscular changes of Cushing’s are easier to control and reverse in the earlier stages of the disease.
Although a swaybacked horse certainly sticks out as abnormal, it’s not clear how much (if any) discomfort the condition will cause. Aged horses in retirement and on turnout usually don’t show any obvious indication that they’re uncomfortable because of the lordosis, including no sensitivity when brushed and no pain on palpation of their backs. There are a few that eventually develop a tendency to stand more stretched out ?'' in the sawhorse stance ?'' which may be an attempt to stretch the back and relieve pressure along the dorsal (top) portions of the spine, where the vertebrae will be closer together than normal.
It certainly stands to reason that if the supporting structures for the spine weaken and allow the vertebrae to fall into abnormal positions that this could eventually result in changes in the spine itself. Unfortunately, there aren’t any large-scale studies specifically of swaybacked horses to tell us how often this might be a problem. One thing is for certain. Their backs aren’t as strong as those of a normal horse.
People considering buying an older horse with a mild swaybacked conformation often want to know if that should be a factor in their decision. That’s a tough question to answer. Some horses naturally carry more of a “dish” to their backs than others. This could predispose them to a more pronounced lordosis as the years go by, but if the shape of their back has essentially been the same throughout adulthood and they’re in work, performing comfortably at a level similar to what you would like the horse to do, it may not be a serious issue.
Definitely find out about any special padding or saddle fit measures the current owners take. Ride the horse or ask your trainer do it to see if you can pick up any issues with poor flexibility or resistance. Be sure you have a veterinarian do a careful prepurchase exam to check for any back pain both before and after work.
If the horse hasn’t been in regular work, and developed the lordosis only later in life, or if the lordosis is obviously more than just a bit of a dip to the back, that’s a different story. A horse like this isn’t a good candidate for regular work since the supporting structures for the back are weakened. Changes to ligaments are essentially irreversible, but you may be able to strengthen the muscular support for the back by careful exercise (see sidebar).
If the horse is still in work but has developed a degree of lordosis, there’s a better chance he can be used for at least light work as long as you are careful to keep him regularly exercised. There’s always a chance the condition is going to progress, but maintaining good muscle tone and avoiding excess weight will slow the worsening.
A horse who is basically retired and swaybacked may be fit for a short, easy ride. Just remember that this horse is out of shape all over, with the weak back needing particular consideration. Before even considering riding, check the back for any signs of tenderness on pressure by pressing gently but firmly along the muscle bellies on both sides of the spine.
Pain may be indicated as an exaggerated dropping away from the pressure, a tensing up against the pressure, or trembling. Ear pinning, raising the neck or elevating the tail may also be seen, as an indication that the horse hurts.
If nothing is found, try riding bareback first. If the horse grunts, sinks, or shows exaggeratedly high head carriage when he feels your weight, it is best not to ride. Otherwise, keep it short, stop at the first sign of any discomfort, and keep it to a walk.
While it’s not proven that a swayback is any weaker than a normal back, common sense tells you to back off if you see signs of pain. Keeping your horse at a normal weight and regularly exercised may help minimize this age-related ailment. Avoid improperly fitted tack and heavy riders. A swaybacked horse may enjoy easy rides, but he is not a candidate for the 20%-rider-weight rule of thumb (the total of the rider and all tack/equipment that the horse carries should not exceed 20% of the horse’s body weight).