Study maps expected peritoneal fluid changes after equine colic surgery

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A prospective study in Veterinary Surgery tracked serial postoperative peritoneal fluid changes in 26 horses after exploratory laparotomy for naturally occurring gastrointestinal disease, including 14 strangulating and 12 non-strangulating lesions. The researchers found that peritoneal lactate and total protein stayed elevated for as long as one week after surgery in both groups, while total nucleated cell count and neutrophil count also rose over time. In other words, postoperative peritoneal fluid abnormalities were common even when horses were recovering, and those values did not reliably separate strangulating from non-strangulating cases after surgery. The paper was published in 2026 and was also presented at the 2025 ACVS Surgery Summit, where it received a highest clinical impact award in the Large Animal Resident’s Forum. (pmc.ncbi.nlm.nih.gov)

Why it matters: For equine veterinarians, the study helps put postoperative abdominocentesis results in context. Peritoneal lactate has long been used preoperatively to help identify ischemic or strangulating lesions, but earlier work has shown that lactate alone can be imperfect even before surgery, especially when comparing strangulating and non-strangulating small intestinal disease. This new study suggests clinicians should be cautious about overinterpreting persistently high postoperative peritoneal lactate or protein as evidence of ongoing strangulation or a surgical complication in the first postoperative week. (pmc.ncbi.nlm.nih.gov)

What to watch: Larger studies will be needed to define which postoperative peritoneal fluid patterns are expected, and which truly signal complications such as ischemia, peritonitis, or the need for reintervention. (pmc.ncbi.nlm.nih.gov)