A horse’s tail is effectively an extension of the thoracolumbosacral region (the back). A normal horse ‘carries’ the tail, so the dock region is variably arched upwards, rather than being clamped to the buttocks, and movement of the tail should mirror the movement of the horse’s vertebral column (Fig. 1). When a horse is moving forwards the thoracolumbar region moves in three ways – flexion and extension (arching and dipping), side to side bending and axial rotation. Side-to-side bending is greatest in walk, but also obviously present in trot and ideally a horse’s tail should swing from side to side in synchrony with movement of the back.
Fig. 1 Normal tail carriage with the tail in the midline but being held higher with greater side to side oscillation in the bigger moving horse on the right compared with the horse on the left with a less animated gait.
Reduced range of motion or stiffening of the back is a common adaptation of horses to lameness as they try to protect themselves to minimise pain. This can also be manifest by reduced range of motion of the tail. The side-to-side movement of the back may become asymmetrical.
In some horses the tail is repeatedly held to one side. The question that then arises is whether a crooked tail is of clinical significance? To try to answer this question a prospective study was performed (1). The movement of the tail in hand, on the lunge and when ridden was documented in all horses undergoing clinical investigation of lameness or poor performance. The tail either oscillated symmetrically from side to side, was permanently held to one side (Fig. 2), or moved from that side to the midline and then back to that side. Alongside this novice to advanced level competition horses were evaluated during warm-up for competitions; for all non-lame horses that were working comfortably the movement of the tail was recorded.
Fig. 2 A crooked tail to the left. When the horse is bearing weight on the left hindlimb and right forelimb in trot (to the left) the tail is further to the left than when the horse is bearing weight on the right hindlimb and the left forelimb (to the right). This event horse had bilateral hindlimb lameness, in part related to lumbosacroiliac joint region pain.
In the horses undergoing clinical investigation the response to palpation of the thoracolumbar muscles was determined and recorded as within the normal range, or the presence of abnormal muscle tension and/or pain. Each horse was stimulated to flex and extend (arch and dip) the back and to flex from side to side; the response was recorded as normal or reduced range of motion. The lame limbs were documented and the presence of saddle slip (the saddle persistently slipping to one side on one or both reins). The final diagnoses based on the response to nerve blocks and diagnostic imaging were also recorded. A horse was determined to have lumbosacroiliac joint region pain if there was improvement in ridden performance approximately 15-25 minutes after local anaesthetic solution was infiltrated around the sacroiliac joints.
There were 520 lame and 170 non-lame sports horses. 32.5% of lame horses had crooked tail carriage, compared with only 5.3% of non-lame horses. Of 169 lame horses with crooked tail carriage, 61% held their tail to the left, 30% to the right and the remaining 9% carried the tail to the left on the left rein and to the right on the right rein. Crooked tail carriage was more common in horses with hindlimb lameness (36%) compared with forelimb lameness (21%). However, there was no association between the side of the predominant lame limb and the direction of crooked tail carriage. Crooked tail carriage was associated with the presence of either lumbosacroiliac joint region pain or increased thoracolumbar epaxial muscle tension. However, there was no relationship between crooked tail carriage and saddle slip (usually a reflection of hindlimb lameness), reduced range of motion of the thoracolumbar, or thoracolumbar epaxial muscle pain.
It was therefore concluded that crooked tail carriage is seen substantially more frequently in lame horses than non-lame horses, especially those with hindlimb lameness. However, there was no association between which was the lamer hindlimb and the direction of the crooked tail, with crookedness to the left predominating. We currently do not fully understand why a crooked tail develops; it may reflect asymmetrical movement of the thoracolumbar region, asymmetry in tone of the specific muscles that control tail movement, or asymmetrical tension in myofascial bands or possibly asymmetry of the rider.
Nonetheless, given the higher prevalence of crooked tail carriage in lame horses compared with non-lame horses, when assessing a horse prior to purchase the presence of a crooked tail is a warning sign that something may not be right.
© Sue Palmer, The Horse Physio, 2021
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