Study examines serial monitoring after equine colic surgery

A new equine clinical research paper in Animals takes on a familiar postoperative problem: how to interpret serial blood, peritoneal fluid, and ultrasound findings in horses recovering from ventral midline exploratory celiotomy for colic. The study followed 36 client-owned horses and set out to define postoperative trends, including L-lactate changes, while also asking whether abdominal ultrasonography could help predict complications. That’s an important question because repeat abdominocentesis and ultrasound are widely used after colic surgery, yet clinicians have had limited prospective reference points for what constitutes expected postoperative change versus a developing complication. (pubmed.ncbi.nlm.nih.gov)

The backdrop is a high-stakes part of equine practice. Horses that need surgical treatment for colic face meaningful risks of postoperative morbidity and death, and the field has been looking for better ways to identify trouble earlier. A Morris Animal Foundation-funded University of Illinois project has explicitly framed this gap, noting that no test reliably predicts which horses will experience complications after colic surgery and positioning peritoneal fluid as a promising source of biologic signals. In parallel, recent reviews have reinforced that peritoneal fluid reflects abdominal pathology more directly than blood in many cases, but that interpretation is complicated by the effects of ischemia, inflammation, contamination, and surgical manipulation. (769b073a.flowpaper.com)

That context helps explain why this study matters. In horses with acute colic, peritoneal fluid analysis is already central to triage, especially when clinicians are weighing strangulating versus non-strangulating lesions. But experts caution that once a horse has been through laparotomy, the abdomen is no longer “baseline.” A 2022 review in the Journal of Veterinary Emergency and Critical Care notes that abdominal fluid variables change in predictable ways with disease, yet should be used to direct treatment rather than as a definitive diagnostic test. A separate 2024 pilot study of 26 postoperative horses similarly found that peritoneal fluid lactate can decline more slowly than systemic lactate because of ongoing intra-abdominal inflammation after surgery. (onlinelibrary.wiley.com)

Ultrasound is the other key piece. Broader equine imaging literature describes abdominal sonography as useful not just for initial colic assessment, but for serial postoperative monitoring of free fluid, intestinal wall thickness, motility, distension, and wound complications. More recent MDPI guidance on equine abdominal point-of-care ultrasound says serial sonographic assessment can help monitor case progression or resolution, and cites postoperative reflux and recovery as areas where repeat intestinal ultrasound can be informative. Separate work has also shown that incision ultrasound can reveal fluid accumulation and other changes suggestive of surgical site infection before drainage is clinically obvious. (mdpi.com)

Taken together, the new Animals paper appears to be less about introducing a brand-new biomarker and more about building a clinical reference framework: what serial venous and peritoneal values look like after surgery, how those trends behave over time, and whether postoperative abdominal ultrasound adds predictive value. Based on the study abstract and related Illinois research, the larger goal is practical decision support for horses in the first days after celiotomy, when clinicians are trying to distinguish expected postoperative inflammation from complications that warrant escalation. (morrisanimalfoundation.org)

Expert commentary in the field supports that framing. Rolfe Radcliffe and colleagues wrote that abdominal fluid interpretation has become central to managing challenging equine colic patients, while stressing that it should be integrated with the rest of the clinical picture, not used in isolation. That caution is especially relevant postoperatively, when inflammation from intestinal handling and surgical trauma can muddy the signal. Inference: if this new study gives clinicians better day-by-day expectations for lactate, protein, cell counts, and ultrasound findings after colic surgery, it could reduce both overreaction to normal postoperative changes and delayed recognition of genuine complications. (onlinelibrary.wiley.com)

Why it matters: For veterinary professionals, especially equine surgeons, internists, emergency clinicians, and referring veterinarians, the value is operational. Postoperative colic cases often hinge on repeated reassessment, and false reassurance can be as costly as unnecessary intervention. Studies across the field have tied colic surgery to frequent postoperative issues, including colic episodes, reflux, incisional infections, hemoperitoneum, and longer-term complications after discharge. Better interpretation of serial peritoneal fluid and ultrasound findings could sharpen monitoring protocols, improve conversations with pet parents about risk and prognosis, and support earlier, more targeted intervention in horses that are starting to drift off course. (thehorse.com)

What to watch: The next step is likely validation and refinement, including whether postoperative fluid and ultrasound patterns can be linked to specific complications strongly enough to support predictive tools, risk scores, or standardized monitoring pathways in referral hospitals. (morrisanimalfoundation.org)