Vertical Frontlimb Ground Reaction Forces of Sound and Lame Warmbloods Differ From Those in Quarter Horses

Abstract

Lameness is a highly prevalent condition in horses and is the principal cause of removal from athletic activity in this species. In evidence-based veterinary medicine studies to evaluate non-setoidal anti-inflammatory drug (NSAID) therapies, force plates are commonly used to objectively assess improvement of lameness. The objective of this study was to determine whether breed differences would influence force plate measurements in sound and lame riding horses. Force plate measurements of lame (n = 20) and sound (n = 18) Warmblood and lame (n = 15) and sound (n = 8) Quarter Horses were compared. Lameness was visually scored using the grade 0–5 American Association of Equine Practitioners (AAEP) lameness scale. Trotting sound Warmbloods loaded their frontlimbs with 118% body weight (BW) and their hindlimbs with 96% BW, whereas Quarter Horses only used 101% BW in the front and 92% BW in the hindlimbs ( P < .05). Furthermore, it appeared and was estimated that, at trot, front-limb-lame Warmblood horses showed higher peak vertical force (PVF) values (grade 2: 89% BW; grade 3: 69% BW), than front-limb-lame Quarter Horses with similar lameness scores (grade 2: 78% BW; grade 3: 66% BW). In conclusion, peak vertical forces (PVF expressed in % BW) of either lame or sound horses seem to be influenced by breed differences between Warmblood and Quarter Horse riding horses. Possible conformation and gait differences enabled trotting Quarter Horses to demonstrate lower absolute PVF values than Warmbloods, whereas trotting lame Warmbloods showed a relatively larger decrease in frontlimb loading and thus in PVF than lame Quarter Horses at a trot. Thus, in studies in which objective lameness observations are recorded, breed differences should be taken into account when specific grades of lameness of a group of horses are to be objectively compared with another group.