Sacroiliac Joint

Sacroiliac pain in horses is a performance limiting condition that can be challenging to diagnose and manage. To understand why horses develop this problem we first need to understand the anatomy involved.

The pelvis is a ring of bones formed of three fused bones; Ilium, ischium and pubis. The lower part of the horses back, the sacrum, is formed of 5 fused vertebrae. The sacroiliac joint (SI) is the joint where the sacrum passes underneath the top of the pelvis (tubera sacrale). The SI joint is strengthened by the ligaments; dorsal, ventral and interosseous sacroiliac ligaments. SI pain is either in-flammation of the joint or ligaments surrounding the joint. The SI joint functions to transfer propulsion from the hindlimbs to the spine, supporting the horses back and driving the horse forward from its hindquarters when in motion.

SI pain typically affects heavier, taller horses usually between the ages of 5 and 15 years old. There is no documented association between a horse’s confirmation and developing SI problems. Warmbloods, Thoroughbreds and Thoroughbred crosses are over represented, as are horses used for show jumping and dressage, which may be due to athletic demands placed on these horses during their work.

The signs that a horse maybe suffering from SI pain are subtle and insidious in onset and progression. Typically the signs are exacerbated when the horse is ridden under-saddle and can be easier to appreciate by the rider than to be seen by an observer. There may be no overt lameness to be seen. Table 1 lists the common signs of SI pain.


Common complaints related to SI pain


* Poor performance / unwillingness to work / holding back


* Lack of impulsion or animation 


* Intermittent lameness


* Reluctance to be shod or have the leg held in a flexed position for a prolonged period of time


* Poor or stilted canter, becoming disunited, taking the wrong lead leg


* Stiff through the back, refusing jumps


* Poor lateral work


* Change in behaviour or performance when worked on the bit


Diagnosis is challenging due to the mass of muscles surrounding the SI joint. A thorough physical exam by a veterinarian is required to rule out other conditions. SI pain is a consequence of a change in the mechanics of the horse’s back and hindlimbs. Therefore conditions such as suspensory ligament desmitis or kissing spines (impinging spinous processes) can be a precursor or sequel to SI pain.

Xray and ultrasound of the SI region is limited due to the anatomy. The most sensitive form of diagnosis is a bone scan (nuclear scintigraphy). The SI joint can also be anaesthetised (blocked) and if there is pain at this site an improvement maybe seen or felt.

Treatment of SI pain requires a combination of medication, physiotherapy and a rehabilitation programme. The SI region can be injected with steroids to reduced inflammation of the joint and ligaments. This will be performed by your veterinarian when required and usually requires more than one treatment. Physiotherapy and rehabilitation are important in making sure the horse works to build up strong muscles around its hind quarters so the SI region is protected and used correctly. Each horse with a diagnosed SI condition will have a tailored rehabilitation program outlining the details of exercises and time period. In feed, anti-inflammatories or joint supplements may be beneficial in reducing in-flammation and promoting healthy joints. Other treatments such as acupuncture or magnetic rugs/boots, may be of benefit however there is little published evidence supporting this.

In summary, the SI is the connection point between the horse and its hindlimbs. The condition mainly affects larger horses undertaking dressage and Show jumping. the signs of SI pain are very subtle. Diagnosis is challenging and treatment involves a combination of medication and rehabilitation.

Chris Baldwin, BVetMed, MRCVS