title: Changes in synovial fluid and serum biomarkers with exercise and early osteoarthritis in horses.
abstract: OBJECTIVE
  To discriminate between changes in biomarkers with exercise compared to changes in biomarkers with osteoarthritis (OA) in exercising horses.
  
  
  METHODS
  Sixteen, 2-year-old horses were randomly assigned either to an exercise-alone (n=8) or OA-affected (also exercised) (n=8) group. All horses had both mid-carpal joints arthroscoped and OA induced in one mid-carpal joint in the OA-affected joints of OA-affected horses. Two weeks after surgery all horses commenced a strenuous exercise program on a high-speed treadmill. Clinical outcomes and synovial fluid and serum biomarkers, were evaluated weekly. Synovial and serum biomarkers evaluated were epitope CS846 (CS846), epitope CPII (CPII), glycosaminoglycans (GAGs), epitope Col CEQ (Col CEQ) (a marker of type II collagen degradation), type I and II collagen degradation fragments (C1,2C), osteocalcin, C-terminal of bone type I collagen (CTX1), type I collagen (Col I) and (synovial fluid only of cartilage) prostaglandin E2 (PGE2) levels. Horses were euthanized at day 91 and their joints assessed grossly, histopathologically, and histochemically.
  
  
  RESULTS
  Exercise induced a significant increase in synovial fluid CS846, CPII, GAG, Col CEQ, C1,2C, osteocalcin and Col I concentrations. There was a significant increase in synovial fluid CS846, CPII, Col CEQ, C1,2C, osteocalcin, Col I and PGE2 concentrations in OA-affected joints compared to exercise-alone joints. The concentration of serum CS846, CPII, GAG, osteocalcin, C1,2C and Col I increased with exercise. For each of these biomarkers there was also a statistically significant increase in serum biomarker levels in OA-affected horses compared to exercise-alone horses.
  
  
  CONCLUSIONS
  Six synovial fluid and serum biomarkers were useful in separating early experimental OA from exercise alone but synovial fluid CTX1 and serum Col CEQ and CTX1 were not.
authors.affiliation: Orthopaedic Research Center, Colorado State University, 300 West Drake, Fort Collins, CO 80523, United States.
authors.forename: D D
authors.initials: DD
authors.lastname: Frisbie
authors.forename: F
authors.initials: F
authors.lastname: Al-Sobayil
authors.forename: R C
authors.initials: RC
authors.lastname: Billinghurst
authors.forename: C E
authors.initials: CE
authors.lastname: Kawcak
authors.forename: C W
authors.initials: CW
authors.lastname: McIlwraith
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006734:Horse Diseases / Q000097:blood*; D006736:Horses; D007794:Lameness, Animal / Q000097:blood*; D010003:Osteoarthritis / Q000097:blood / Q000662:veterinary*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D044967:Serum / Q000378:metabolism; D013223:Statistics as Topic; D013582:Synovial Fluid / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D024043:Collagen Type II