Subchondral cysts (p 963) may be seen in both the distal radius and the carpus. Many, particularly when bilateral and in the ulnar carpal bone, are normal. However, they are commonly symptomatic in the distal radius. They are diagnosed by radiography, and if conservative treatment does not solve the problem, arthroscopic debridement is done.
Infectious (septic) arthritis of the carpal joints is relatively rare. The most common cause is iatrogenic, in association with intra-articular injections. Horses show severe lameness and marked synovial effusion, as well as more peripheral swelling in the joint. Heat, pain, and synovial fluid changes are obvious. Synovial fluid WBC counts >30,000 and usually 100,000 cells/mm3, protein levels of 4–6 g/dL in the presence of low viscosity, and a serosanguineous appearance are typical findings. For treatment, see Arthropathies in Large Animals: Subchondral Cystic Lesions.
Last full review/revision March 2012 by Stephen B. Adams, DVM, MS, DACVS; Andrew L. Crawford, BVetMed, CertES (Orth), MRCVS; James K. Belknap, DVM, PhD, DACVS; Jane C. Boswell, MA, VetMB, CertVA, CertES (Orth), DECVS, MRCVS; Peter Clegg, MA, Vet MB, PhD, CertEO, DECVS, MRCVS; Marcus J. Head, BVetMed, MRCVS; C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DACVS; James Schumacher, DVM, MS, DACVS, MRCVS; John Schumacher, DVM, MS, DACVS, MRCVS; Roger K. W. Smith, MA, VetMB, PhD, DEO, DECVS, MRCVS; Chris Whitton, BVSc, FACVSc, PhD; Jean-Marie Denoix, DVM, PhD, Agregé; Joerg A. Auer, DrMedVet, Dr h c, MS, DACVS, DECVS