title: Incomplete longitudinal fractures and fatigue injury of the proximopalmar medial aspect of the third metacarpal bone in 55 horses.
abstract: BACKGROUND
  Previous descriptions of incomplete longitudinal fractures and fatigue injury of the proximopalmar aspect of the third metacarpal bone (McIII) have focused on diagnostic imaging findings, especially in racehorses.
  
  
  OBJECTIVE
  To document the case details, clinical features, response to diagnostic analgesia, diagnostic imaging findings and follow-up data in a large group of horses with an incomplete longitudinal fracture or fatigue injury of the proximopalmar medial aspect of the McIII.
  
  
  METHODS
  Horses were included in the study if pain was localised to the proximopalmar aspect of the metacarpal region, with radiological evidence of an incomplete longitudinal fracture or generalised increased radiopacity in the proximopalmar medial aspect of the McIII, or focal increased radiopharmaceutical uptake (IRU) in the proximopalmar aspect of the McIII. Age, breed, gender, height, bodyweight, work discipline, work history, duration of lameness, clinical signs and responses to diagnostic analgesia were recorded. Radiographic and scintigraphic images were assessed subjectively and objectively.
  
  
  RESULTS
  There were 55 horses representing a broad spectrum of ages and work disciplines, 73% of which had radiological abnormalities. The majority had no localising clinical signs, although 73% of horses with radiological abnormalities showed a characteristic pattern of lameness. Lameness was generally worse in straight lines than in circles. Increased radiopharmaceutical uptake ranged from mild to intense in the lame limb; 14% of nonlame limbs had mild IRU. Of horses for which long-term follow-up was available, 98% returned to full athletic function.
  
  
  CONCLUSIONS
  Incomplete longitudinal fractures and fatigue injury of the proximopalmar medial aspect of the McIII may occur in horses of many types and sports disciplines, and are not confined to immature performance horses. They should be considered an important differential diagnosis for proximal metacarpal region pain.
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Newmarket, UK.
authors.forename: R
authors.initials: R
authors.lastname: Morgan
authors.forename: S
authors.initials: S
authors.lastname: Dyson
mesh_terms: D000818:Animals; D005260:Female; D005552:Forelimb / Q000000981:diagnostic imaging / Q000473:pathology*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy / Q000662:veterinary*; D006734:Horse Diseases / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D006736:Horses; D008297:Male; D010805:Physical Conditioning, Animal; D011859:Radiography; D014463:Ultrasonography