Scoliosis in Adult Equines

Q: I purchased my Thoroughbred gelding when he was 5 years old. Within the next two years we were doing really well at entry level dressage. He looked and behaved fantastically.

Then the problems started. As I ride on my own and hadn't had this problem before, it took me a while to figure out that his refusing to go (forward), bucking, and general naughtiness was not disobedience at all, but serious pain from a saddle that was a bad fit. It seemed to be blocking his shoulder movement and extending the pain right through to his hindquarters.

We trekked five hours down to Johannesburg for a new, properly fitted saddle, X rays of his spine, and physiotherapy.

I changed his routine completely from mainly arena work to mainly trail riding, and I just didn't feel he was getting much better. It was on my fifth saddle fitting with the same qualified saddle-fitter that she noticed his spine is skewed to the left.

Do you think that through some imbalance in my posture I caused this crookedness in his spine? Could it be caused by overschooling with pain and incorrect muscle use? Or do you think that the scoliosis was always there and that it has just become worse over the years?

He is on lysine (an amino acid critical for growth as well as muscle and tissue development) and a joint supplement. His teeth are done regularly, and his feet are good (I went so far as to check his angles and breakover with the American Farrier's Association through sending pictures).

Can scoliosis be corrected with work and stronger muscles to support the spine?

Natasha van der Walt, Louis Trichardt, South Africa

A: Scoliosis is a (pathological) condition of the spine where there is a kind of S-shaped deformation of the spine in the lateral plane. That means the spine is not straight as it is supposed to be from head to tail, but has an S shape (like a snake) in the spine to the left and right, in most cases in the chest or loin region.

Scoliosis usually is a developmental condition occurring after birth. During the growth period of the young horse there might be imbalances (due to feed/work/injury/genetics, etc.) causing spinal deformation, resulting in deformation of the bony structures. This situation is permanent, and it will limit the horse in his normal mobility of the spine. Depending on the kind of work the horse is doing, this could be a problem. You can imagine that for trail riding the horse does not need a lot of flexibility to the sides in its spine, while in jumping or dressage this can clearly be a limitation. With time the scoliosis can become more prominent due to adaptations of the spine due to loading. Also muscles might become atrophied and the spinal curvature could become more pronounced. Realize that when scoliosis is more chronic, quite often the abnormal shape of the spine will limit the flexibility, but the process is not particularly painful.

Scoliosis also can be an acquired condition developing later in life. Injury to the certain spinal structures (intervertebral disk, facet joint, vertebral body fracture) causes parts of the spine to be painful or nonfunctional. Due to pain the muscles around the spine try to protect the affected area and contract (spasm). When this situation goes for a long period of time, the shape of the spine can be altered and develop the same S shape known as scoliosis. This type of scoliosis has the tendency to get worse with time, especially when the originating cause is not treated. Also, when the originating cause is not treated, quite often the horse will experience pain.

In the developmental condition there is not a lot we can do to influence the outcome. However, when the scoliosis is acquired, especially if caught in an early stage, dealing with the originating injury might stop the process of deformation of the spine. Rehabilitation with specific exercises can assist in treating the primary injury, as well as dealing with the acquired S shape, and they can make the horse more comfortable and less crooked. A correct diagnosis is a first step in this process, and a complete physical exam, followed by diagnostic procedures, such as scintigraphy (bone scan), X rays, and ultrasonography, should be performed, but I am not sure if these modalities are available around where you live.

About the Author

Rob van Wessum, DVM, MS

Rob van Wessum, DVM, MS, Cert. Pract. KNMvD (Equine Practice), is an Assistant Professor in the Department of Large Animal Sciences and Sport Horse Lameness Clinician at Michigan State University's College of Veterinary Medicine.

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