Can We Manipulate the Horse’s Spine Effectively?

Introduction

Manipulation is a manual procedure that involves a directed thrust to move a joint past the physiological range of motion without exceeding the anatomical limit [1]; i.e., the joint is brought to the end of passive range of movement and further moved into the paraphysiological space [2]. Spinal manipulation (adjustment) involves the use of a nonrepetitive, short (or long) lever, high-velocity, low-amplitude thrust directed at one or more of the joints of the vertebral column [1,2], with the intent of reducing pain and muscle hypertonicity, and increasing joint range of motion [3].

Mechanism of action

Traditional chiropractic medicine has focused on modulating the function of the nervous system, which subsequently leads to self-healing [4]. As such, the goal of spinal manipulation is not only or necessarily to create a mechanical effect (returning a vertebra to a specific position) but also and maybe more so to initiate or activate the homeostatic mechanism of vertebral movement/kinesthetics, with its subsequent neurological response [1,2].

Specific to normal joint function, both joint play and end- feel movements need to be present, but end-feel movements can only be affected when the joint is taken through the elastic barrier, creating a sudden yielding of the joint and a characteristic cracking noise (cavitation). This action can only be accomplished through the mechanical effect of a high-velocity, low amplitude thrust (manipulation) or deep mobilisation [5].

The ability to effectively manipulate the horses’ spine can be seen in a clinical setting when the equine chiropractor induces a cavitation during manipulation. This is further supported by one study, showing that substantial segmental spinal motions could be induced by chiropractic manipulation [6].

Dosage and outcome

The research regarding the effects of equine spinal manipulation is limited, but all report positive effects [7-17].

A single treatment session generally has an immediate effect that lasts up to 1 to 3 weeks [8,18]. However, to achieve the desired long-term and cumulative therapeutic effects, several treatment sessions (two or three sessions at 1 to 3-week intervals) are required [8,18].

A recent systemic review concluded that there is low-to- moderate quality evidence that various types of joint mobilisation or manipulation will reduce pain, muscle hypertonicity, and stiffness [18]. 

When it comes to treating acute back pain, a multimodal approach is likely needed [16], whereas spinal manipulation as a single modality can be quite effective to alter muscle tone, activity, and balance [9,14,15], as well as improve thoracolumbar flexibility and movement symmetry [8,10,12,13].

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