title: Occult subchondral osseous cyst-like lesions of the equine tarsocrural joint.
abstract: OBJECTIVE
  To report the clinical signs, diagnosis, management, and outcome of horses with occult sub-chondral osseous cyst-like lesions of the tarsocrural joint.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Twelve horses with subchondral osseous cyst-like lesions (SOCLs) in the tarsocrural joint.
  
  
  METHODS
  Information about history, examination findings, diagnostic techniques, and surgical procedures as obtained from medical records. Outcome was determined by patient re-evaluation and telephone communication with the referring veterinarian, owner, or trainer.
  
  
  RESULTS
  Horses were aged from 3 to 29 years. Lameness (2 weeks to 1 year) varied from moderate to severe. Synovial fluid analyses (9 horses) yielded changes consistent with suppurative inflammation and positive bacterial culture was obtained in 4 horses. Eight of 9 horses that had intra-articular analgesia had a dramatic reduction in lameness. No abnormalities were detected on tarsal radiographs in 10 horses. Scintigraphy identified foci of increased radiopharmaceutical uptake in the distal tibia or talus of all horses, and the lesion was further characterized by computed tomography in 7 horses. SOCLs were identified in the medial malleolus (5), intertrochlear groove of the talus (4), lateral malleolus (2), and distal intermediate ridge of the tibia (1). One horse was euthanatized, 6 horses had surgical debridement, and 5 horses were managed conservatively. Four horses treated surgically (67%) returned to soundness. Conservatively treated horses continued to exhibit lameness but 2 were sufficiently sound for light pleasure riding.
  
  
  CONCLUSIONS
  Occult lesions of the tarsus not visible on radiographs can be detected by computed tomography and scintigraphy and may be a source of lameness.
  
  
  CONCLUSIONS
  SOCL, possibly of septic origin, should be a differential diagnosis for persistent lameness localized to the tarsocrural joint without radiographic abnormalities. Surgical debridement of the lesions may offer the best prognosis for a return to athletic soundness.
authors.affiliation: Department of Clinical Sciences, Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA. jose.garcia-lopez@tufts.edu
authors.forename: José M
authors.initials: JM
authors.lastname: García-López
authors.forename: Carl A
authors.initials: CA
authors.lastname: Kirker-Head
mesh_terms: D000818:Animals; D001845:Bone Cysts / Q000175:diagnosis / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D006736:Horses; D007794:Lameness, Animal; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D011996:Records / Q000662:veterinary; D012189:Retrospective Studies; D013585:Synovitis / Q000150:complications / Q000175:diagnosis / Q000662:veterinary; D013643:Tarsus, Animal / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000662:veterinary