Association of blood lactate concentration and outcome in foals.
Authors: Wotman K, Wilkins P A, Palmer J E, Boston R C
Journal: Journal of veterinary internal medicine
Summary
# Blood Lactate as a Prognostic Marker in Critically Ill Foals Elevated blood lactate concentration is a recognised indicator of tissue hypoxia and cellular dysfunction in critically ill patients, yet its specific prognostic value in neonatal foals had not been systematically evaluated prior to this 2009 study. Researchers conducted a retrospective analysis of 225 foals admitted to a neonatal intensive care unit, measuring arterial or umbilical blood lactate at admission, 24 hours, and 48 hours post-admission, then correlating these values and their rate of change with short-term survival outcomes and clinical parameters including blood pressure and bacteraemia status. The findings demonstrated that surviving foals had significantly lower lactate concentrations at all time points, and crucially, foals whose lactate *decreased* over the first 24 hours had substantially better survival odds—a 156% increase in odds of 96-hour survival for each 1.0 mmol/L daily improvement—whereas every 1 mmol/L increase in admission lactate reduced survival odds by 18–53% depending on timepoint. The authors propose 6.5 mmol/L as an admission cut-point for 96-hour mortality prediction and 5.5 mmol/L for discharge outcome, with the important caveat that the lactate–blood pressure relationship only became statistically significant when excluding foals with severe hypotension and low lactate, suggesting these parameters work synergistically in prognostication. For practitioners managing critically ill foals, serial lactate monitoring—particularly tracking the *trajectory* of decline—offers a quantifiable, objective tool for assessing treatment response and counselling on prognosis, though the authors rightly call for prospective validation of these cut-points before implementing them routinely into clinical decision-making
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Practical Takeaways
- •Blood lactate concentration is a valuable prognostic indicator in sick neonatal foals—higher lactate at admission correlates with worse outcomes, making it useful for triage and prognosis discussion with owners
- •Lactate trend (improvement vs. worsening) over the first 24 hours is more predictive of survival than a single measurement, so serial monitoring is essential for assessing treatment response
- •Use proposed cut-points (6.5 mmol/L at admission for 96-hour prognosis; 5.5 mmol/L for discharge prognosis) to guide clinical decision-making and intensity of care in neonatal foals with sepsis or critical illness
Key Findings
- •Blood lactate concentration was significantly lower in surviving foals at 96 hours and discharge compared to non-survivors across all measurement times
- •For every 1 mmol/L increase in lactate at admission, odds of 96-hour survival decreased 18% and discharge survival decreased 22%
- •Change in lactate over time (admission to 24 hours) showed strongest predictive value: 1.0 mmol/L/day increase in lactate clearance associated with 156% increased odds of 96-hour survival
- •Proposed admission lactate cut-points of 6.5 mmol/L for 96-hour survival and 5.5 mmol/L for discharge survival warrant prospective validation