Association between Eosinophil Count and Cortisol Concentrations in Equids Admitted in the Emergency Unit with Abdominal Pain.

Simple Summary: Acute stress can manifest physiologically through a "stress leukogram" (neutrophilia, eosinopenia, lymphopenia, and mild monocytosis), with eosinopenia as one of its main indicators. Changes in cortisol concentrations, the primary stress biomarker, whether measured in blood or saliva, strongly correlate with the severity of gastrointestinal diseases in equids. Recently, eosinophil count has been used to identify critically ill horses and as a prognostic marker in horses with Systemic Inflammatory Response Syndrome or SIRS. However, the relationship between both parameters has not been proven. Therefore, the objective of this study was to assess the possible differences in eosinophil count in horses with acute abdominal diseases that survived and non-survived upon hospitalization and its relationship with salivary cortisol. It was demonstrated that non-surviving horses showed the lowest eosinophil count, and a strong correlation (negative) was observed between cortisol and eosinophil count. Thus, eosinophil count could be a potential prognosis biomarker in horses with acute abdominal diseases. Stress leukogram includes eosinopenia as one of its main markers (neutrophilia, eosinopenia, lymphopenia, and mild monocytosis). Cortisol is the main stress biomarker, which is also strongly correlated with the severity of gastrointestinal diseases. This study aimed to determine the relationship between salivary cortisol and the eosinophil cell count (EC) in equids with abdominal pain. To do this, 39 horses with abdominal pain referred to an emergency service were included. All samples were taken on admission, and several parameters and clinical data were included. Equids were classified according to the outcome as survivors and non-survivors. Non-surviving equids presented higher salivary cortisol concentrations (Non-Survivors: 1.580 ± 0.816 µg/dL; Survivors 0.988 ± 0.653 µg/dL; p < 0.05) and lower EC (Non-Survivors: 0.0000 × 10³/µL (0.000/0.0075); Survivors: 0.0450 × 10³/µL (0.010/0.1825); p < 0.01). In addition, the relationship between salivary cortisol concentration, EC, and the WBC was determined. Only a strong correlation (negative) was observed between cortisol and EC (r = −0.523, p < 0.01). Since cortisol is not an analyte that can be measured routinely in clinical settings such as emergencies, the EC could be a good alternative. While the results are promising, further studies are needed before EC can be used confidently in routine practice to predict survival in cases of abdominal pain. [ABSTRACT FROM AUTHOR]