# Hematologic Ratios in Donkeys: Reference Intervals and Response to Experimentally Induced Endotoxemia

## TL;DR

This study establishes reference intervals for hematologic ratios in donkeys and shows how they change during experimentally induced endotoxemia, which could help in diagnosing this condition in donkeys.

## Contribution

The study provides the first reference intervals for hematologic ratios in donkeys and evaluates their response to endotoxemia.

## Key findings

- Most hematologic ratios showed significant changes after LPS infusion in donkeys.
- The neutrophil to lymphocyte ratio decreased similarly to septic foals.
- Red cell distribution width to platelet ratio did not change in donkeys, unlike in septic foals.

## Abstract

Donkeys commonly suffer from endotoxemia as a complication of other diseases such as colic, pleuropneumonia, or diarrhea. Although new hematologic ratios are used in human medicine and foals to diagnose and determine the outcome in sepsis, no data are available in donkeys. Reference intervals for these ratios were established in adult healthy donkeys. LPS infusion caused significant variations in most of the ratios studied, with changes in the neutrophil to lymphocyte ratio being similar to the ones reported in septic foals. However, no changes in the red cell distribution width to platelet ratio were observed, contrary to septic foals. Moreover, reported cut-off values in foals should not be used in donkeys. In conclusion, these ratios are informative for donkeys and could be useful in the diagnosis of endotoxemia. More studies evaluating the changes in these ratios in different diseases and specific cut-off values in this species are necessary.

Endotoxemia is commonly observed in donkeys, secondary to colic, pleuropneumonia, or diarrhea among other disorders. Hematologic ratios are new biomarkers widely used in the diagnosis and prognosis of multiple conditions in human medicine, including sepsis. While the utility of these ratios has been proved in septic foals, no data are available on donkeys. Moreover, reference intervals (RIs) have not been studied in this species. In this study, RIs of the most commonly reported hematologic ratios were determined in 73 healthy adult donkeys. In addition, variations in these ratios in response to LPS infusion were also evaluated in six healthy adult donkeys. Most of the ratios evaluated showed significant variations after induced endotoxemia, with most of them showing values outside of the established RIs. Similarly to septic foals, the neutrophil to lymphocyte ratio was significantly reduced after LPS infusion. No significant changes were observed in the red cell distribution width to platelet ratio, contrary to reports on septic foals. Previously reported cut-off values for both of these ratios should not be extrapolated to donkeys. Future studies evaluating these ratios in natural endotoxemia or other diseases in donkeys, as well as establishing species-specific cut-off values, are necessary.