title: Histopathologic features of distal tarsal joint cartilage and subchondral bone in ridden and pasture-exercised horses.
abstract: OBJECTIVE
  To determine whether histopathologic characteristics of the osteochondral units of equine distal tarsal joints were associated with exercise history in horses without lameness.
  
  
  METHODS
  30 cadaver tarsi from horses without lameness and with known exercise history were separated into 3 groups: nonridden, pasture exercise (group P); low-intensity, ridden exercise (group L); and high-intensity, elite competition exercise (group E).
  
  
  METHODS
  Standardized sites from the centrodistal and tarsometatarsal joints under went histologic preparation. A grading system was adapted to describe location, depth, and shape of lesions; cellular arrangement; organization at cartilage and subchondral bone (SCB) junctions; and organization of SCB. A high score signified a more severe pathological change than a low score. Exercise groups were compared by calculation of Spearman rank correlations.
  
  
  RESULTS
  In the centrodistal joint, lesions were present in groups L and E but only medially. Cellular arrangement scores were higher at the dorsomedial location in group P than in groups L and E. Groups L and E had higher scores than group P for the organization of the cartilage, SCB junctions, and SCB, with higher scores at the dorsomedial location. In the tarsometatarsal joint, lesions were evident across the whole joint surface, with more severe lesions located laterally in all 3 groups. Overall, group E had higher scores for cellular arrangement and SCB organization than groups P and L.
  
  
  CONCLUSIONS
  Ridden exercise may increase the risk of osteochondral lesions at distal tarsal sites predisposed to osteoarthritis relative to the risk with nonridden exercise.
authors.affiliation: Centre for Equine Studies, The Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, England. carolyne.tranquille@aht.org.uk
authors.forename: Carolyne A
authors.initials: CA
authors.lastname: Tranquille
authors.forename: Sue J
authors.initials: SJ
authors.lastname: Dyson
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Blunden
authors.forename: Simon N
authors.initials: SN
authors.lastname: Collins
authors.forename: Tim D H
authors.initials: TD
authors.lastname: Parkin
authors.forename: Allen E
authors.initials: AE
authors.lastname: Goodship
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Murray
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000473:pathology*; D002102:Cadaver; D002356:Cartilage / Q000473:pathology*; D006736:Horses / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D013640:Tarsal Joints / Q000473:pathology*