Reference intervals of acute phase proteins in healthy Andalusian donkeys and response to experimentally induced endotoxemia

BACKGROUND: Assessment of acute phase proteins (APPs) may allow prompt detection of diseases in donkeys, that otherwise may be missed because of the stoic behavior of donkeys. Reference intervals (RIs) of APPs measured using immunoassays and a comparison of the response of these biomarkers to a controlled inflammatory insult are lacking in donkeys. OBJECTIVES: (a) To describe the RIs for APPs in healthy Andalusian donkeys, (b) to study the effects of sex and age on APPs, and (c) to assess the early response of APPs to experimentally induced endotoxemia. ANIMALS: Seventy‐three healthy Andalusian donkeys (67 for RIs and 6 for endotoxemia). METHODS: Serum amyloid A (SAA), haptoglobin (Hp), C‐reactive protein (CRP), ceruloplasmin (Cp), α1‐acid glycoprotein (AGP), procalcitonin (PCT), ferritin (Ft), and fibrinogen (Fb) RIs were determined. Endotoxemia was induced and samples for APP determination were obtained at regular intervals for 4 hours. RESULTS: The RIs in Andalusian donkeys were: SAA (0.1‐0.6 mg/L), Hp (75‐2261 mg/L), CRP (1.3‐7.0 mg/L), Cp (0‐745 mg/L), AGP (0‐884 mg/L), PCT (0‐504 pg/mL), Ft (26.9‐31.8 μg/L), and Fb (115‐466 mg/dL). Concentrations of SAA were higher (P < .05) in jacks. Donkeys <5 years old had higher Cp, AGP, and PCT compared to older donkeys. Concentrations of SAA and Hp were significantly increased in endotoxemic donkeys from 2 hours postinduction. CONCLUSIONS AND CLINICAL IMPORTANCE: We illustrated the importance of using species‐specific RIs for APPs in donkeys and the effect of age and sex on APP concentrations. Concentrations of SAA and Hp appear to be the most useful biomarkers in donkeys in the early stages of endotoxemia.