Swaybacks arent pretty, but they dont necessarily cause the horse to be in pain. Photo by Sue Tomkin.

 
Swayback—technically called “lordosis”—is the deeply sagging top line that develops in some older horses.  Swayback, lordosis, is caused by weakness and laxity/stretching of the supporting ligaments along the horse's spine, often with weakness and loss of bulk/tone in the top line musculature. 

Risk Factors
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.

Predictions, Prevention
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.

Put It To Use • Avoid allowing the horse to get overweight. • Continue regular exercise, as weak muscles add to the problem. • Be sure saddle fit is perfect; consider a cutback saddle. • Don’t allow heavy riders to mount up. • Check for Cushing's.

Consequences
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.

Precautions
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.

Retirees
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.

Bottom Line
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).

Cushing’s Disease And Swayback Rapid development (over months) of a swaybacked appearance with a pendulous abdomen can be a symptom of Cushing’s disease, a pituitary tumor common in older horses. The cause is overstimulation of the adrenal glands to produce the hormone cortisol.  Cortisol interferes with the muscle cell’s ability to utilize fuels, resulting in weakness and loss of muscle bulk.

Back Exercises
While there’s not much you can do about overstretched ligaments, the muscles supporting the spine respond well to conditioning exercises.  Before starting an exercise program, make sure the horse doesn’t have any lameness issues behind that would interfere with his ability to engage his hindquarters and work well under himself.

Back exercises are best done from the ground, without the inhibiting effect and extra strain of a rider’s weight. Anything that encourages the horse to work well under himself and in a rounded frame helps to strengthen the back.  These include:
• Carrot stretches (see May 2004) and stroking along the midline of the belly with enough pressure to make the horse arch his back.
• Line driving, with good contact with the bit.  Eventually, if the horse is up to it, this can progress to work with a light cart.
• Free longeing at an animated walk and controlled but energetic trot, as long as the horse drops his head enough to round the back and brings his hindquarters under him.
• Longeing with a harness and side reins adjusted so that they’re not overly restrictive but are most comfortable when he lowers his head and flexes at the poll enough to slightly round and stretch his back.  Again, a strong walk and engaged trot are best.
• Longeing over ground poles encourages the horse to drop his head and round his back

The goal is not to make the horse break a sweat and definitely not to cause any fatigue.  Start slow, with things the horse tolerates easily, and gradually increase the difficulty.

Padding And Saddle Fit
Since lordosis is caused by a combination of gravity, weight and conformation, nothing you do in terms of saddle fit or padding is going to have much effect.  However, because the support system of the back is weakened, make sure weight is being evenly distributed.  Cut-back saddles usually work best because of the prominent withers. 

Check saddle fit meticulously. Additional thick foam padding to help raise the position of the saddle to a more normal one is helpful.  Always remember, though, that the rider’s weight, and therefore the force it puts on the back, is the same regardless of how much padding you use.  A swaybacked horse is a poor choice for a large rider.

Congenital Swayback
A small number of extremely young horses (less than 1 year old) may also develop lordosis. This may be a randomly occurring birth defect, or in the case of some Saddlebred lines, is likely to be genetic. The problem is caused by malformed vertebrae that are narrower at their base than normal, causing the bottoms of the vertebrae to line up in the dished, swayback configuration rather than as a straight spine.  Young horses with this problem may also have scoliosis, a twisting of the spine out of its straight line configuration when viewed from the top.