ESTABLISHING REFERENCE INTERVALS FOR SERUM INFLAMMATORY MARKERS AND INVESTIGATING THEIR STORAGE STABILITY AND CLINICAL UTILITY IN ASIAN WILD HORSES (EQUUS FERUS PRZEWALSKII) UNDER MANAGED CARE.

Abstract

Acute phase proteins (APPs) are commonly used in domestic equine practice, where they rise rapidly in response to inflammation and decrease soon after resolution. This response provides useful information to identify, monitor, and prognosticate a variety of inflammatory conditions. Asian wild horses (Equus ferus przewalskii) are an endangered relative of the domestic horse, and APP reference intervals (RI) and clinical utility in this species are not well documented. This study used serum samples from clinically healthy Asian wild horses under managed care to establish RI for serum amyloid A (SAA, n = 21) using an equine SAA assay and haptoglobin (HP, n = 23) using a proprietary assay. The utility of SAA and HP in identifying inflammation in clinically abnormal horses was assessed, and storage stability of these analytes under refrigerated conditions was determined. The RIs established in this study were 0.3-6.8 mg/L for SAA and 0-3.25 g/L for HP. Six clinically abnormal cases were retrospectively assessed using the RI established in this study. One case of pituitary neoplasia showed elevated SAA levels, one case of maxillary lip phaeohyphomycosis and concurrent endometritis showed elevations in SAA and HP, and one case of chronic laminitis had elevated SAA. Storage stability of SAA and HP were assessed at 4°C over 7 d. SAA significantly decreased between Time 0 h and Time 72 h, but increased again at 7 d with no significant difference between Time 0 h and Time 7 d. Because of the initial decrease in SAA concentration over the first 72 h, it is recommended that SAA is analyzed within 48 h if freezing or immediate analysis is not possible. There was no significant difference between HP between Time 0 h and Time 7 d, suggesting stability of this analyte over this period if freezing or immediate analysis is not possible.