Table 2.

Summary of five original research papers describing the use of L-lactate in the equine patient with colic.

Author, Year	Evaluated in Blood/Plasma and/or Peritoneal Fluid	Major Findings	Clinical Relevance
Shearer, 2018 [14]	Blood and peritoneal fluid	No significant difference was found in blood and peritoneal fluid L-lactate values from horses with non-strangulating and strangulating intestinal lesions. However, the peritoneal fluid L-lactate to blood lactate ratio was significantly elevated in horses with strangulating intestinal lesions.	The peritoneal fluid L-lactate to blood L-lactate ratio may help differentiate strangulating from non-strangulating intestinal lesions.
Kilcoyne, 2019 [97]	Plasma and peritoneal fluid	Peritoneal L-lactate of 3.75 mmol/L was highly specific (92%) and moderately sensitive (81%) for predicting a strangulating intestinal lesion in colicking horses.	Elevated peritoneal fluid L-lactate is a strong indicator of intestinal ischemia.
Delesalle, 2007 [105]	Plasma and peritoneal fluid	Significantly elevated blood and peritoneal fluid L-lactate values were found in horses with strangulating lesions versus non-strangulating lesions and in horses that required colic surgery compared to horses medically managed. Peritoneal fluid L-lactate was significantly more elevated than blood L-lactate in horses that did not survive.	While both blood and peritoneal fluid L-lactates can be prognostic indicators in horses with colic, peritoneal fluid L-lactate is more predictive for intestinal ischemia and case outcome than blood L-lactate.
Latson, 2005 [6]	Plasma and peritoneal fluid	Horses affected with strangulating or non-strangulating intestinal lesions had significantly elevated peritoneal fluid and plasma L-lactate levels compared to normal horses. L-lactate levels were more significantly elevated in peritoneal fluid than plasma in horses with intestinal strangulation and ischemia.	Peritoneal fluid L-lactate is a better predictor of strangulating lesions and intestinal ischemia than blood L-lactate levels.
Peloso, 2012 [106]	Blood and peritoneal fluid	Peritoneal fluid L-lactate levels were significantly higher at admission to the hospital and after 6 h of hospitalization in horses with strangulating lesions than non-strangulating lesions. Horses with strangulating lesions had significantly elevated peritoneal fluid-to-blood L-lactate ratios compared to horses with non-strangulating lesions. Peritoneal fluid L-lactate >4 mmol/L and an increase in peritoneal fluid L-lactate levels over time were predictive for strangulating intestinal lesions.	Peritoneal fluid L-lactate levels can be used to help differentiate between strangulating and non-strangulating intestinal lesions in horses with colic.