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

Abstract

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.

Keywords: biomarker; colic; cortisol; eosinophils; horses; survival.

Figure 1

Comparison between survival and non-survival equids regarding salivary cortisol (n = 39, A), EC (n = 30, B), and WBC (n = 35, C) in horses admitted to an equine hospital with acute abdominal pain. Data are presented as mean ± SD (A,C) and median ± standard error of the mean (B). Statistical analysis was performed using a Student’s t-test if data showed normal distribution or the Mann–Whitney test if no normal distribution was presented. n.s. no significance.

Figure 2

Correlation coefficient (r) between salivary cortisol, EC (A), and WBC (B). Statistical analysis was performed using Spearman’s rho coefficient (A) and Pearson’s coefficient (B). Graphics show a regression line with 95% confidence bands.