Canter dysfunction & lumbosacroiliac joint region pain

“Management of lumbosacroiliac joint region pain includes local medication, manual therapy and groundwork to strengthen the supporting muscles, and appropriate modification of the training and management programme. This is often a long-term project rather than a ‘one-off’ treatment.” - Dr. Sue Dyson

Problems with canter are often seen in association with lack of hindlimb engagement and impulsion reflecting bilateral hindlimb lameness either due to a primary hindlimb cause and/ or a component of lumbosacroiliac joint region pain. We use the term lumbosacroiliac joint region pain because we cannot be sure exactly where the source(s) of pain is (are) in individual horses - we just know that if we place local anaesthetic solution adjacent to or in the sacroiliac joints the horse’s ridden performance improves dramatically. In a study of 296 horses with lumbosacroiliac joint region pain, verified by improvement in performance after diagnostic anaesthesia of the area, ridden canter quality was worse than trot quality in 73% (Barstow and Dyson 2015).

Affected horses invariably appear much worse when evaluated ridden compared with in hand and on the lunge. Some horses (21%) buck going into canter or during canter. These bucks are ‘u-shaped’ and although uncomfortable for a rider, it does not feel as though the horse is going to buck the rider off. In addition, some horses (17%) which buck will also kick out behind with one hindlimb. If you see a showjumper land after jumping a big fence and then buck and kick out this is often a reflection of lumbosacroiliac joint region pain.

Other common canter problems associated with lumbosacroiliac joint region pain include reluctance to canter, breaking from canter to trot, close spatial and temporal placement of the hindlimbs (at worst, so-called ‘bunny-hopping), becoming disunited, lack of a suspension phase, being on the forehand, crookedness, a stiff, stilted canter lacking hindlimb impulsion and engagement (loss of power) and reluctance to perform flying changes. However, these problems are non-specific.

If the problem is long-standing (chronic) then affected horses often lose the ‘top-line’muscles in the lumbar region (the croup) and the hindquarters resulting in prominence of the summits of the lumbar spinous processes (a ‘roached’ appearance) and the tubera sacrale (jumper’s bump). Moreover, the horse may change its posture so that

the hindlimbs are camped under the trunk, and the tubera sacrale may appear higher than the withers. Horses often develop hypertonicity (tightness) of the lumbar muscles and are reactive to firm pressure being applied over the tubera sacrale, seen as the horse partially flexing the hindlimbs, rather than resisting that pressure. Some horses become difficult to trim and shoe because an affected horse may be uncomfortable standing on one hindlimb alone.

Some horses have lumbosacroiliac joint region pain alone, whereas in others the problem occurs in association with other hindlimb lameness such as proximal suspensory desmopathy. Paradoxically in some horses if the pain causing hindlimb

lameness is abolished by nerve blocks the horse may trot sound, with increased hindlimb impulsion and engagement, but the quality of the canter may deteriorate, because the balance of where the horse feels uncomfortable has changed. This emphasises the need to evaluate a horse which is performing poorly when ridden and to assess both trot and canter, both before and after nerve blocks.

Although some of these clinical signs are suggestive of a component of lumbosacroiliac joint region pain, the only way in which a diagnosis can be reached reliably is by the response to nerve blocks. Skeletal scintigraphy (a bone scan) is

unreliable, with a large proportion of false negative and false positive results. Ultrasonography performed per rectum allows evaluation of the caudal margin (the back edge) of the sacroiliac joints, the lumbosacral joints and some nerve roots, but the absence of any detectable abnormalities does not preclude pain. A positive response to medication of the region verifies the diagnosis, but a negative response does not eliminate the lumbosacroiliac joint region as a source of pain. Not all horses respond to treatment.

Management of lumbosacroiliac joint region pain includes local medication, manual therapy and groundwork to strengthen the supporting muscles, and appropriate modification of the training and management programme. This is often a long-term project rather than a ‘one-off’ treatment.

REFERENCES

Barstow, A., Dyson, S. Clinical features and diagnosis of sacroiliac joint region pain in 296 horses: 2004 – 2014. Equine Vet. Educ. 2015, 27: 637-647

© Sue Dyson 2023