FES and Sacroiliac Pain: A Diagnostic Aid for Hind-End Lameness
Sacroiliac (SI) joint pain is a challenging cause of poor performance to diagnose in sport horses. These horses may not appear overtly lame, yet under saddle they struggle with propulsion, balance, and engagement.
At Daniel Equine, we use a range of tools to detect SI dysfunction—especially in subtle or compensated cases. While no single test is definitive, Functional Electrical Stimulation (FES) offers a unique advantage by providing real-time feedback on how the gluteal and core muscle groups are functioning.
This article outlines one of several approaches used to help identify SI pain. **The list is not exhaustive, but highlights where FES plays a role in the diagnostic process.**
What Is FES?
Functional Electrical Stimulation uses targeted electrical pulses to activate muscle groups in a controlled, therapeutic pattern. It’s commonly used for:
– Core and gluteal strengthening
– Muscle recovery post-injury
– Conditioning support in horses returning to work
Beyond rehabilitation, FES gives us unique insights into neuromuscular function, revealing asymmetry, compensation patterns, and poor muscle activation—especially in the pelvic region.
Using FES to Help Diagnose SI Dysfunction
When applied to the gluteal and core musculature, FES can highlight red flags that suggest sacroiliac discomfort or dysfunction:
– Poor contraction on one side
– Delayed or inconsistent firing of gluteal groups
– Muscle fasciculations or twitching during stimulation
– Discomfort or reactivity during treatment in specific patterns
Horses with SI-related pain often fail to recruit their hind-end properly during FES, even at low settings. This mirrors the clinical presentation under saddle—resistance, loss of propulsion, and poor pelvic engagement.
Subtle Signs Under Saddle
In our experience, approximately 1 in every 10 horses with clinically significant SI pain will not exhibit palpable soreness during a standard exam. These horses may pass flexions and palpation but show clear dysfunction when ridden. Common signs include:
– Slow or delayed lead changes at the canter
– Bilateral hindlimb lameness that “switches sides”
– Poor pushoff or weak hind-end engagement
– Inability to lift the pelvis or sit through transitions
In these cases, FES becomes a valuable tool to observe muscle performance and symmetry in real time—offering insight where static exams fall short.
Why It Works
Unlike imaging, FES allows us to observe functional muscle response, not just structure. In horses with vague lameness or back pain, it can help determine whether the core and gluteal chains are neurologically engaged—or inhibited due to discomfort.
We often combine FES findings with:
– Ultrasound of the lumbosacral and pelvic region
– Dynamic examination under saddle or in hand
– Response to SI blocks or targeted therapy
Case Insight: When the Usual Work-Up Isn’t Enough
In several performance horses, FES has revealed asymmetric gluteal recruitment—despite normal imaging and flexion exams. These findings led to SI-focused diagnostics and treatment, including joint injection, targeted core therapy, and customized rehab programs. Without FES, the dysfunction may have been missed or dismissed as training resistance.
Diagnosis Through Therapy
At Daniel Equine, we believe in using every tool available to get answers—especially in complex or subtle cases. FES offers a low-risk, non-invasive method to gain insight into muscle health and pain response. In horses with poor performance, unexplained hindlimb weakness, or recurrent back issues, FES can serve as a functional diagnostic aid.
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