title: Serum and Synovial Fluid Serum Amyloid A Response in Equine Models of Synovitis and Septic Arthritis.
abstract: OBJECTIVE
  To investigate the serum and synovial fluid serum amyloid A (SAA) response in equine models of synovitis and septic arthritis and to compare handheld and validated immunoturbidometric assays for SAA quantification.
  
  
  METHODS
  Controlled, experimental study.
  
  
  METHODS
  Healthy adult horses (n = 9).
  
  
  METHODS
  Synovitis (n = 4) and septic arthritis (n = 5) were induced using lipopolysaccharide and Staphylococcus aureus, respectively, and serial serum and synovial fluid samples were collected. Serial synovial fluid cytology was performed for both models and synovial fluid from the septic arthritis model was submitted for bacterial culture. Serum and synovial fluid SAA were quantified by handheld test and immunoturbidometric assay. Cytologic and SAA data were compared within and between models (mixed model ANOVA) and results of SAA assays were compared using category-by-category analysis (weighted kappa coefficient).
  
  
  RESULTS
  Synovial fluid total nucleated cell counts and total protein increased significantly following induction of both models. Serum and synovial fluid SAA remained normal in synovitis horses and increased significantly in septic arthritis horses. Serum SAA increased more rapidly than synovial fluid SAA. Agreement was 98% when SAA concentrations were low (<50 μg/mL) but the assays diverged when concentrations were greater than ∼100 μg/mL. Overall, there was good category-by-category agreement between SAA assays (weighted kappa = 0.824).
  
  
  CONCLUSIONS
  Serum and synovial fluid SAA may be useful adjuncts in diagnosing septic arthritis in horses. SAA concentrations for the assays diverged and examination using a larger sample size is needed before direct numeric comparisons between the assays can be made.
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Elsa K
authors: EK
authors: Ludwig
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia.
authors: R
authors: R
authors: Brandon Wiese
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Megan R
authors: MR
authors: Graham
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Amelia J
authors: AJ
authors: Tyler
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Julie M
authors: JM
authors: Settlage
authors: Laboratory for Study Design and Statistical Analysis, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia.
authors: Stephen R
authors: SR
authors: Werre
authors: Department of Dairy Science, College of Agriculture and Life Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Christina S
authors: CS
authors: Petersson-Wolfe
authors: Department of Dairy Science, College of Agriculture and Life Sciences, Virginia Tech, Blacksburg, Virginia.
authors: Isis
authors: I
authors: Kanevsky-Mullarky
authors: Department of Large Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia. lad11@vt.edu.
authors: Linda A
authors: LA
authors: Dahlgren
mesh_terms: D000818:Animals; D001170:Arthritis, Infectious / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*; D004195:Disease Models, Animal; D005260:Female; D006734:Horse Diseases / Q000209:etiology / Q000378:metabolism*; D006736:Horses; D007118:Immunoassay / Q000379:methods / Q000662:veterinary*; D008297:Male; D009391:Nephelometry and Turbidimetry / Q000379:methods / Q000662:veterinary*; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D013582:Synovial Fluid / Q000737:chemistry; D013585:Synovitis / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*
chemical_list: D000685:Serum Amyloid A Protein