Serum amyloid A, haptoglobin, and ferritin in horses with colic: Association with common clinicopathological variables and short-term outcome

Equine colic may be associated with an acute phase response (APR). Measurement of acute phase proteins (APPs) allows the detection of an APR and may help clinicians in monitoring the disease; however, the role of APPs in colic is unclear. This study aimed to evaluate the clinical usefulness of serum amyloid A (SAA), haptoglobin and ferritin in combination with an extended clinicopathological profile in equine colic. The medical records of 54 horses were retrospectively selected. Horses were grouped based on outcome (survivors vs. non-survivors), diagnosis (ischaemic/strangulating vs. non-ischaemic/nonstrangulating), and treatment (medical treatment vs. surgery). Laboratory data were compared, and a logistic regression analysis was performed for outcome prediction upon admission. A high percentage of horses had abnormal SAA (29/54), haptoglobin (20/54), and ferritin (31/54) concentrations. In particular, haptoglobin was below the reference interval in 13/54 horses. Non-survivors had significantly decreased haptoglobin and increased ferritin concentrations compared with survivors. The ischaemic/strangulating group had significantly increased creatinine and ferritin and decreased haptoglobin concentrations compared with the non-ischaemic/non-strangulating group. Creatinine was the only significant predictor of mortality in the regression analysis. In conclusion, APPs including SAA, haptoglobin, and ferritin combined with clinicopathological variables may help clinicians to understand the pathogenesis of APR and underline potential complications of equine colic. The reduction in haptoglobin concentration may suggest haemolysis or muscle fibre damage; ferritin may indicate alteration in iron metabolism and tissue damage. Further prospective studies are needed to assess diagnostic and prognostic values of APPs in colic horses.