Denise A. Gorondy, DVM
A: The sacroiliac joint of the horse is a very important part of the equine musculoskeletal system. The sacroiliac joint is located in the pelvic region of the horse and connects the pelvis to the sacral portion of the vertebral column. The sacroiliac region consists of a joint and multiple ligaments. It differs from other joints in the body in that there is very limited movement in the joint space. The sacroiliac joint functions to transfer energy or propulsion from the hind limbs thru the spine and to support the weight of the horse’s torso.
Injury to the sacroiliac region is not uncommon however, it can be difficult to pinpoint. The injury can occur when abnormal rotational forces are placed on the sacroiliac region such as when a horse’s hind limbs splay out/abduct excessively, a single limb slipping out as it pushes off the ground, or repetitive stress in an incorrect frame. Injury to the area can affect either the joint, the ligaments, or both. Sacroiliac injuries can be acute or chronic in nature and potentially progress to arthritis. A horse that has injured the sacroiliac region can present with a true lameness or with vague clinical signs. To an untrained eye, the injured horse may appear fine. However, they often have subtle changes in performance and gait biomechanics that can be felt by the rider or observed by a trained eye. Clinical signs of a horse with an injured sacroiliac region include:
- Back pain
- Lack of impulsion
- Traveling with a narrow gait behind
- A “pacey” gait at the walk
- Difficulty standing square behind
- Difficulty standing with one hind limb elevated for feet picking or farrier work
- Unable to track straight especially on a circle with the haunches on a different tract than the front end
- Carrying the tail off to one side
- “Bunny hopping” at the canter
- Reluctance to work on the bit
- Difficulty with flying lead changes
- Reluctance or refusal to jump
- Reduced flexibility of the lumbosacral region
- Asymmetry of pelvic musculature
At the initial onset of injury, the horse will have splinting and pain in the affected area with moderate to severe secondary muscle spasms that prevent the joint from returning to its normal position and function. If the injury is addressed quickly and appropriately, good results and resolution can often be achieved. However, immediate treatment is often not provided and the horse gets into a cycle of repeated re-injury of the area. Ultimately, this horse develops notable pelvic asymmetry.
Diagnosis of a sacroiliac injury can be challenging and oftentimes is definitively diagnosed with a bone scan. There are instances where sacroiliac injury is suspected and therapies are instituted with a monitored response. Treatment for acute injury to the sacroiliac region involves rest from riding with restricted activity but typically not complete stall rest, anti-inflammatory medications, chiropractic and acupuncture, manual therapy to resolve muscle spasms, and stretching. Once the initial moderate to severe pain is resolved, a gradual re-introduction to controlled exercise begins typically with in hand work progressing back to under saddle work. Once back under saddle, specific exercises are recommended to strengthen the musculature associated with pelvic stabilization in an effort to prevent re-injury. Treatment for chronic sacroiliac injuries include all of the above and additionally treatment with sacroiliac joint injections, OsPhos, or pentosan.
In all horses that have recovered from an injury to the sacroiliac joint, overall fitness, hind end strength, proper biomechanics, and engagement of the musculoskeletal system are paramount in preventing re-injury. Horses that have injured the sacroiliac region can return to their previous level of athleticism if the injury is addressed early and treated appropriately. However, because of the challenges associated with the presentation and diagnosis of this injury, it often times results in the horse returning to a lower level of athleticism.