Systemic serum amyloid A in early (<24 h) diagnosis of acute synovial structure involvement in horses with penetrating limb injuries.

Synovial structure involvement secondary to limb injury is a common emergency in equine practice, requiring an accurate initial diagnosis for immediate treatment. This study aimed to investigate the clinical usefulness of Serum amyloid A (SAA) in the initial diagnosis of synovial structure involvement caused by acute (<24 h) penetrating limb injuries in horses and to correlate SAA with standard diagnostic parameters. Fifty-five horses with acute limb injuries were divided into two groups: Group 1 (G1, n = 26) with a diagnosis of penetrating synovial trauma and Group 2 (G2, n = 29) without synovial structure penetration. Serum SAA, white blood cell (WBC) count and fibrinogen as well as clinical criteria and synovial fluid parameters were assessed on admission. The two groups were compared using a two-sample t-test (metric parameters) or a Wilcoxon-Mann-Whitney test (ordinal parameters). Correlation was determined between serum SAA and the following parameters: WBC count, fibrinogen, synovial total nucleated cell count (TNCC) and percentage of neutrophils (% N), body temperature and the degree of lameness. Serum SAA concentrations were not different between G1 and G2; however, there were statistically significant differences in general health, the degree of lameness, and synovial fluid parameters. In G1, serum SAA concentrations positively correlated with fibrinogen concentrations and synovial fluid % N. Nonetheless, SAA cannot be used as a sole tool to diagnose synovial structure involvement caused by limb injuries. Synovial fluid parameters remain the most important tool in the diagnosis of synovial penetration. In cases where synoviocentesis fails or is not possible, serum SAA might support diagnosis.