An investigation of the association between hindlimb conformation and suspensory desmopathy in sports horses

Abstract

Proximal suspensory desmopathy (PSD) is a common cause of hindlimb lameness in sports horses; anecdotally there is an association with straight hock conformation. The objective of this prospective observational study is to describe hindlimb conformation in horses with and without bilateral PSD. Horses examined over one year with a definitive diagnosis for lameness (based on clinical assessment, response to diagnostic anaesthesia, radiography, ultrasonography AE MRI or scintigraphy), were included (n = 193). Markers were placed on predefined landmarks. Lateral photographs were acquired from the left and right sides with the horse standing squarely, using standardised techniques, with each metatarsus perpendicular to the ground, aligned to the tuber ischii marker. Before data acquisition, repeatability studies for marker placement, horse positioning and angle measurements were performed. The tarsal and metatarsophalangeal angles were measured using Image Measurement. Orthopaedic diagnosis, breed, work discipline, weight, height and age were recorded. Z-tests, Fisher's exact tests, Chi-squared tests and multivariable logistic regression were used to determine the associations between diagnosis, tarsal angles and possible confounding variables. Mann Whitney U tests were used to evaluate the relationship between metatarsophalangeal joint angle and suspensory ligament injury. Horses with PSD had larger tarsal angles than controls (P = 0.003). The proportions of Warmblood-type horses and dressage horses with PSD were different to those of other breeds and work disciplines (P = 0.001, 0.02 respectively). A final logistic regression model demonstrated a significant effect of mean tarsal angle on outcome when breed and weight-height product were accounted for. There was a an 11% increase in the odds of PSD for every degree increase in tarsal angle (CI 1.006-1.223, P = 0.04). There was no association between suspensory ligament injury and metatarsophalangeal joint angle. Assessment of tarsal angles at prepurchase examinations and prior to surgical treatment of PSD may be advisable.

An investigation into the occurrence of, and risk factors for, concurrent suspensory ligament injuries in horses with hindlimb proximal suspensory desmopathy

“…However, in a previous study, there was no association between tarsal angle and age (Routh et al . ). A genetic predisposition for degenerative SL disease has been recognised in the Peruvian Paso breed (Plaas et al .…”

“…; Routh et al . ). In the 10‐year period of the current study from 2009, 2296 horses underwent orthopaedic examination at the AHT, of which 40.2% had hindlimb PSD.…”

“…genetic predisposition, static or dynamic conformation [Routh et al . ]), rather than biomechanical forces associated with work (Murray et al . ; Walker et al .…”

“…; Dyson and Murray ; Routh et al . ). An influence of biomechanical forces related to the type of work has been described (Murray et al .…”

“…; Routh et al . ). There is a relationship between a large tarsal angle and hindlimb PSD (Routh et al .…”