How to Look for Sacroiliac Disease During Lameness Examination: Some Simple Clinical Indicators

1. Introduction

Back pain, and more specifically sacroiliac pain, has become a commonly recognized cause of reduced performance in the horse in the last decade.^1–6 Many improvements in diagnostics and therapy have been made, and treating sacroiliac problems in horses is now part of many sport medicine practices.³

In general, complaints about sacroiliac pain in horses are diverse.^1–4 Coming to a diagnosis can be a daunting task and often involves several diagnostic tools to exclude other sources of reduced performance.^4–6 When a clinician, confronted with a case of suspected sacroiliac disease, has a “checklist” of clinical symptoms or indicators related to sacroiliac disease to rely on, the likelihood of recognizing the dysfunction is improved.^7,8 The more “iliosacral related” symptoms that are present at initial clinical examination, the more likely it is that the horse is suffering from sacroiliac disease.^7–11

Some of these parameters are excellent indicators for spinal dysfunction or pathology, and incorporating an evaluation of these parameters into the standard clinical exam for lameness or performance related complaints can be very helpful to the lameness clinician, as they may otherwise be easily overlooked. 

2. Materials and Methods

When sacroiliac pathology is present, the normal movement of the sacroiliac region of the horse will be compromised.^1,3,5,6 Altered sarcoiliac mobility can be associated with several very specific alterations in the normal gait patterns in the horse.^7,8 A short description of these gait alterations and how to evaluate them during a clinical exam is listed below.

Tracking Narrow Behind 

One of the first alterations of gait due to sacroiliac dysfunction, tracking narrow behind, is often visible in walk and even more obvious in trot. In walk, there are always at least 2 limbs on the ground in the support phase, whereas in trot there is a suspension phase with no limbs on the ground and then a diagonal support phase with 2 limbs on the ground,¹² making loading and rotational forces on the sacroiliac region more pronounced. When sacral rotation is avoided, the horse will place the hind feet close together, what is called narrow behind. It can look like the horse is walking or trotting on a cord as the hind feet are placed on the same line in front of each other.^7,8

Lateral Walk

When observing the walk on a straight line, the walk should be a clear 4 beat motion.¹¹ When spinal dysfunction is present and the horse is asked to perform a serpentine in hand, the walk becomes more lateral, similar to a pace (hind limb and front limb on the same side advance at the same time). This finding has been associated with cervical spinal cord compression (“Wobbler’s”) but is not well described with other spinal dysfunction. In the author’s opinion, the loss of a 4 beat walk is a clear indicator of tension (pain?) and decreased mobility in the spine.^8,9

The best way to evaluate for the symptoms of lateral walk and narrow behind is to first have the horse walk and trot in hand to and from the examiner/clinician, as in any lameness exam, and then to have the horse walk again but in a serpentine pattern. Observing the horse from the side when it passes by on the straight line can also be very helpful.

Haunches In/Out

When observing a horse going away and coming at the clinician, the front limbs and the hind limbs should be on 2 tracks, the hind limbs follow the front limbs in the same plane. With sacral dysfunction, one hip is often kept slightly lower (may be subtle), resulting in a slight bending to one side. When the haunches are brought to one side, the observer notes that the horse is on 3 or more tracks. The hind limbs do not follow the front limbs in the same plane but are placed laterally, away from the central axis. This is easily observed when the horse is lunged on a circle. If the haunches are more in, one sees the front limbs making a circle with a slightly larger diameter than the hind limbs. Conversely, when the haunches are out, the hind limbs travel on a larger diameter. In canter, younger/untrained horses often have a slight haunches in at the canter, but nearly every “normal moving” horse should be tracking straight (“true”) in walk and trot on a 25 to 30 foot diameter circle.

Asymmetric Tail Position

The best way to evaluate tail position is to observe the walk in a straight line and in a serpentine away from the clinician.^7,8 When observed from behind, a horse’s tail should be in a relatively central position, and when walking serpentine, the tail should remain in a midposition with slight movements toward the side of the bending in the serpentine. When sacral dysfunction is present, the tail may be held asymmetrically. When the tail is held to one side, and stays to one side in the serpentine, there is a clear indication of sacroiliac dysfunction.^7,8 

Bunny Hop Canter

The fourth gait alteration often associated with sacroiliac dysfunction is a deterioration of the quality of the canter. This may even be a clear complaint of the client! A normal canter is 3 beats, and the motion of the left lead and right lead should be comparable and relatively symmetric.¹¹ There is a clear moment of suspension, and when the footfalls are observed as the feet land in their specific pattern, there is a clear separation of the landing moments between the two hind feet.¹¹

When sacroiliac dysfunction is present, this clear 3 beat is less obvious or will completely disappear. The hind feet may land nearly at the same moment and very close together.^7-10 A good way to describe this phenomenon is “bunny hop.” ^7–10

Observing the horse in a relaxed canter (tension in the horse can mimic the bunny hop canter without indicating true spinal dysfunction) in both leads on a lunge or ridden facilitates the evaluation of the canter. The author would advise having the horse do some canter for several minutes in each direction, so it is possible to analyze the quality of the canter over time and not be distracted by initial behavior such as excitement, bucking, etc.

Reduced Flexibility of the Lumbosacral Region

The last part of the exam for achieving information about the sacroiliac region is “hands-on.” After observing the flexibility of the lumbosacral region in walk, trot, and canter, now the clinician evaluates the flexibility by manipulating it.

With one hand on the tuber coxae and one hand on the tail, lateral flexion in both directions is tested by simultaneously pulling on the tail and pushing slightly on the tuber coxae.^7,8 Ventral flexion is evaluated by making the horse “tuck under” by scratching it with a pointy object on the hamstrings on each side.^7,8 Lateral and ventral flexibility should be symmetrical. Clear reduction of lateral and/or ventral flexibility is a good indicator for sacroiliac dysfunction.⁸

3. Results

In the author’s practice, we have included the serpentine in walk, lunging at all 3 gaits, and the manipulation of the lumbosacral region as a standard protocol in every lameness exam. During 9 years of practice (2005–2014), the author has examined 811 cases with a complaint of reduced performance or subtle hind limb lameness. Of these, 327 (40%) were diagnosed with sacroiliac disease based on clinical exam, imaging data (ultrasonography and scintigraphy), and improvement in symptoms or abnormal diagnostic findings at 2, 4, and 6 month recheck intervals after initial treatment and rehab. Of these 327 cases of diagnosed and clinically substantiated sacroiliac disease, 322 had a positive score (“present”) for at least 3 indicators mentioned above. [...]