In February 2024, Sue Dyson, MA, VetMB, PhD, DEO, DECVSMR, FRCVS, presented a webinar through The Equine Practice Company to equine practitioners from around the globe on lumbosacroiliac region pain in horses.
This condition is generally a cause of poor performance with a lack of hind-limb impulsion and engagement rather than lameness, she explained. Affected horses are consistently worse when ridden than when presented in hand or on the longe line. Canter is worse than trot under saddle. Dyson explained that canter is an asymmetrical gait that is initiated with the trailing hind limb bearing weight alone, which creates asymmetrical forces through the sacroiliac (SI) joint. When the horse is affected by more than one problem, the clinical signs referable to the SI joint might deteriorate after removing other sources of pain.
Pain from the lumbosacroiliac (LSI) region is often associated with pathological changes in the SI joint but also might extend into the caudal lumbar articulations. We don’t yet know if these are predisposing causes or if they contribute to pain, said Dyson. Lumbosacroiliac region pain can be not only a primary problem but might also occur secondary to other causes of hind-limb lameness, especially with proximal suspensory ligament disease.
Common Clinical Signs of LSI Joint Region Pain
Dyson described many signs associated with LSI joint region pain. Affected horses might display any of these signs along with abnormal behavior when ridden. Some are pathognomonic for the syndrome.
- The horse shows no gait abnormality when in hand or on longe but displays abnormal behavior and movement when ridden, especially at canter.
- Atrophy and/or poor development of thoracolumbar epaxial muscles that results in abnormal prominence of the summits of the lumbar spinous processes. This is a typical presentation.
- Abnormal concavity or lordosis of the thoracolumbar region between the prominence of the tuber sacrale and summits of spinous processes.
- Change in a horse’s posture such that the tuber sacrale sit higher than the withers. If you apply pressure to the ventral sternum (i.e., thoracic lift), and the horse lowers his croup so the tuber sacrale is lower than the withers, this is a good prognostic sign. In contrast, a horse that cannot change its posture with a thoracic lift displays a more adverse prognostic sign.
- The horse might stand with the hind limbs positioned under the trunk.
- Abnormal asymmetrical hair wear in the caudal thoracic regions might reflect abnormal saddle movement as the saddle slips to one side. In one study, said Dyson, the saddle slipped to the side of the lamer hind limb in 87% of horses with hind-limb pain.
- Hypertonicity with or without pain in the lumbar epaxial muscles.
- Abnormal reaction when applying pressure over the tuber sacrale—the horse sinks down on the hindquarters with stifle flexion. This is almost pathognomonic of LSI region pain. Not all horses affected with LSI discomfort show this abnormal reaction with palpation of the SI area.
- Abnormal reaction to palpation of the brachiocephalic muscles is reflective of how the horse carries its head and neck to compensate for LSI region joint pain when ridden.
- Head and nose tilt under saddle, the horse often taking a stronger hold in one hand than the other.
- Lack of hind-limb impulsion and engagement of the hind end.
- Lack of suspension phase in canter with abnormal elevation of the forehand at canter to increase extension of the LSI region.
- Bucking and kicking out behind are pathognomonic for LSI nerve pain. SI joint pain is typically associated with a U-shaped buck that extends the thoracolumbar region rather than an N-shaped buck that flexes that region.
- Head tossing not related to idiopathic headshaking.
- Spooking behavior or scooting forward.
- Crooked tail carriage might signify thoracolumbar epaxial muscle tension or SI joint region pain.
- Difficulty getting down on the ground to lie down or roll. The horse might hold the croup high like a cow and then flop over.
Diagnosis
It’s important to watch the horse do the full range of movements he is expected to do during ridden exercise, stressed Dyson. Diagnosing LSI region joint pain relies specifically on periarticular anesthesia of the SI joints that infuses local anesthetic beneath both tuber sacrale. While this block is not specific because it can diffuse cranially, it is highly informative. If the horse does not improve in canter following periarticular anesthesia and/or ridden horse pain ethogram scores remain high, then it is important to look for another area of concern.
Dyson said in her experience, nuclear scintigraphy is unreliable because of its many false positives and negatives. The best imaging uses ultrasound per rectum of the SI joint and caudal margins of the LS joint, discs, and lumbosacral transverse joints, she said. Pathological changes in these joints foretell a more guarded prognosis.
Many horses don’t tend to respond to a non-steroidal anti-inflammatory trial, even at high doses. A negative response doesn’t mean anything, Dyson noted, and a positive response simply means there is underlying pain but does not specify where.
Treatment and Management
Treatment response might be less effective than the results seen with diagnostic analgesia, said Dyson. Treatment failure does not preclude a component of LSI joint region pain. She stressed that medical treatment alone is not reliable for managing this problem. It is just as important to address how a horse is ridden and trained to enhance stability of the hind limbs and thoracolumbar region.
For treatment, Dyson said she infiltrates the LSI area with corticosteroids—prednisone acetate or triamcinolone—diluted with 10 milliliters Sarapin. The steroid dose depends on the horse’s body condition score due to the risk of triggering laminitis in obese horses. The dose also depends on the problem’s chronicity; the horse’s size, weight, and height; and the competition schedule.
A team-based approach that includes physiotherapy exercises and core stabilization achieves the best results. Efforts to improve a horse’s posture at rest and during ridden exercise are important. If the horse is uncomfortable when ridden, then it is better to work him in hand and do groundwork instead. Riders should avoid asking the horse to do what makes him uncomfortable, such as canter efforts, said Dyson. A graded return to ridden exercise works best when the rider is in a two-point position at the canter rather than sitting in the saddle.
Dyson advocates a combination of exercise and physiotherapy:
- Carrot/baited stretch exercises.
- Pessoa longing system as a training aid.
- Resistance bands.
- Poles and raised poles.
- Horse walker.
- Backing.
- Circling.
- Correct tack fit.
- A good rider who is capable of riding in balance and encouraging the horse to stretch its topline.
Horses with a chronic LSI problem exceeding six months have a guarded prognosis. If a horse affected by LSI region joint pain is recognized early and a good management program is implemented, he has a 40% chance of success in returning to full athletic function, said Dyson. This requires ongoing management, including a specific competition schedule and SI injections every four to six months with early recognition of recurrence of pain.
