Sidewinder Syndrome in a 25 Year Old Welsh Cob Stallion

Sidewinder syndrome in a 25 year old welsh cob stallion

Introduction
Recently, ‘sidewinder’ or ‘crabwalker’ syndrome has been described in, generally older, horses with an acute onset of an off-track gait and movement of the hind limbs. However, the exact etiology remains unknown.

Case description
A 25 year old welsh cob stallion was presented with a sudden onset of an abnormal pelvic limb gait. The horse was unable to stand ‘square’, putting the right hind leg left to the median line, continuously leaning the pelvis to the right with a rather extended left hind leg. Often, the horse slowly spinned to the left because of continuous swaying of the pelvic limbs to the right. The horse was more comfortable when leaning the right hind leg against the stable wall. At walk the right hind leg was put to the right of the right foreleg while the left hind leg was approximately in line with the right foreleg. When walking in freedom the stallion usually made a circling movement in order to approach a target. Vital signs and blood examination were normal. No nervous deficits were found. Magnetic Motoric Evoked Potential exam, needle electromyography and radiography were normal. Treatment with NSAID and steroids did not change the clinical signs and 4 months after initial presentation the stallion was euthanized. At necropsy bilateral degenerative hip joint disease was found. Lesions were more severe at the left side with partial rupture of the left ligamentum capitis femoris. Histologically, this ligament showed fragmented collagen fibers, proteoglycan increase and cellular infiltrate. […]