# Prognostic Significance of Erythrocyte Sedimentation Rate for Survival in Equine Colic

## TL;DR

Low erythrocyte sedimentation rate (ESR) at admission is linked to poor survival in horses with colic, suggesting it could help identify at-risk animals early.

## Contribution

This study is the first to characterize ESR behavior in equine colic and demonstrate its potential as an early prognostic tool.

## Key findings

- Non-survivors had significantly lower ESR at admission compared to survivors.
- ESR increased in surviving horses within 24 hours but remained low in non-survivors.
- Low ESR at admission is associated with poor survival outcomes in horses undergoing colic surgery.

## Abstract

Colic is one of the most common and severe emergencies in horses and continues to represent a major cause of death in equine practice. One of the main clinical challenges is identifying, as early as possible, which horses are at greater risk of deterioration or death, particularly at the time of hospital admission when rapid decisions are required. Although several biomarkers are used to support prognostic evaluation, many of them increase slowly and may be of limited value during the early stages of severe disease. In this study, we investigated the erythrocyte sedimentation rate, a non-specific indicator of systemic inflammation widely used in human medicine and recently made available for routine use in horses through automated analysis. This parameter was measured at admission in horses presenting with colic and, in surgical cases, again 24 h later. Horses that did not survive showed markedly lower values at presentation compared to survivors. These results suggest that low erythrocyte sedimentation rate values at admission may be associated with severe systemic compromise. Given that this test is rapid, inexpensive and easy to perform, it may represent a valuable additional tool to support early prognostic assessment in horses with colic.

Accurate early prognostic assessment is a central aspect of clinical decision-making in horses presenting with colic. Despite the availability of multiple clinical and laboratory parameters, reliable biomarkers that provide useful information at the time of admission remain limited. The erythrocyte sedimentation rate is a non-specific indicator of systemic inflammation that has recently been validated for automated point-of-care use in horses. Its behaviour in equine colic has not been previously characterised. This study included 85 horses admitted for colic at two university referral hospitals. The erythrocyte sedimentation rate was measured at admission in all horses and again approximately 24 h after surgery in a subset of surgical cases. Horses were classified as medically managed, surgical survivors or surgical non-survivors. Group comparisons were performed using non-parametric statistical methods, and associations with survival were evaluated. The admission erythrocyte sedimentation rate was significantly lower in surgical non-survivors compared to the other groups (p < 0.05). Erythrocyte sedimentation rate rose in surviving horses within 24 h, while it barely changed among non-survivors, and there were no significant changes among surgical values. Actually, these observations suggest that low erythrocyte sedimentation rates on admission are associated with low chances of survival for horses undergoing colic surgery and thus make these rates a feasible additional prognostic indicator for equine colic.