Blood test misses mark for detecting ulcer pain in horses
Bottom line
A University of Adelaide study suggests a blood-based immune test won’t solve the long-running problem of identifying pain in horses with equine gastric ulcer syndrome, or EGUS. In the study, published August 26, 2026, in The Veterinary Journal, researchers tested whether interleukin-1 beta release from stimulated peripheral blood mononuclear cells could distinguish horses with gastric lesions from those without them. It couldn’t. Of 64 horses included in the final analysis, 59 had gastric lesions, and only 25% showed a measurable blood-cell response, with no significant association between that response and EGUS status. The authors said the findings point to a mismatch between localized gastric disease and what circulating immune cells can detect. (pubmed.ncbi.nlm.nih.gov)
Why it matters: For equine practitioners, the result is a useful negative finding. EGUS is common, especially in performance horses, but clinical signs are often subtle, inconsistent, or absent, and lesion severity doesn’t neatly map to pain. That leaves veterinarians balancing gastroscopy, history, management factors, and behavior when deciding how much weight to give a suspected ulcer diagnosis. Recent equine guidance continues to treat gastroscopy as the only definitive diagnostic tool, while reviews of EGUS biomarkers describe the field as active but unsettled. (cehhorsereport.vetmed.ucdavis.edu)
What to watch: Expect follow-up work on larger cohorts and multimodal pain assessment strategies that combine biomarkers with horse-specific behavioral and inflammation measures, rather than relying on a single blood test. (equusmagazine.com)
Key facts
- Study type
- University of Adelaide study
- Publication date
- August 26, 2026
- Journal
- The Veterinary Journal
- Question tested
- Whether IL-1β release from stimulated peripheral blood mononuclear cells could distinguish horses with gastric lesions from those without them
- Sample size
- 64 horses in the final analysis
- Gastric lesions
- 59 horses had gastric lesions
- Assay response
- 25% showed a measurable blood-cell response
- Main finding
- The blood-based assay did not significantly correlate with EGUS status
- Clinical takeaway
- Gastroscopy remains the definitive test for presence, type, and severity of ulcers
A new equine study has ruled out one more candidate in the search for an objective pain test for gastric ulcers. Researchers at the University of Adelaide reported that a blood-based assay centered on interleukin-1 beta, or IL-1β, release from stimulated immune cells did not reliably identify horses with equine gastric ulcer syndrome. The paper was published August 26, 2026, in The Veterinary Journal. (pubmed.ncbi.nlm.nih.gov)
That matters because EGUS remains one of the more frustrating syndromes in equine practice. Horses can carry gastric lesions with few outward signs, and when signs do appear, they’re often nonspecific: poor performance, attitude changes, appetite shifts, or intermittent discomfort. UC Davis guidance for horse caregivers notes that other diagnostic approaches have been explored, but none has shown the specificity or sensitivity needed to replace gastroscopy, which remains the definitive test for presence, type, and severity of ulcers. (cehhorsereport.vetmed.ucdavis.edu)
In the Adelaide study, investigators asked whether peripheral blood mononuclear cells, after ex vivo stimulation of toll-like receptors 2 and 4, would release IL-1β in a way that tracked with gastric lesions used as a proxy for presumed EGUS-associated pain. According to the study summary and university release, 64 horses were included in the final analysis, 59 of them had gastric lesions, and just 25% showed a measurable response in the assay. That response did not significantly correlate with EGUS status, and facial pain scores also did not differ significantly between responders and nonresponders. (pubmed.ncbi.nlm.nih.gov)
The finding fits with a broader theme in equine gastric disease research: promising biomarkers rarely translate cleanly into practical screening tools. A 2026 review in Equine Veterinary Education describes a wide but still unsettled biomarker landscape, including serum proteins, oxidative stress markers, cortisol-related measures, and salivary analytes. Some candidates have shown potential in specific settings, but the field still lacks a robust, field-ready marker that can reliably tell veterinarians which horses have clinically meaningful ulcer-associated pain. (beva.onlinelibrary.wiley.com)
Public expert reaction has been measured rather than dismissive. In the university release, lead author Gustavo Ferlini Agne said the study highlights how difficult it is to identify pain in animals that can’t localize or describe it, and argued that negative findings still help narrow the field. He also said future work should focus on larger studies and methods better tailored to horses, including combinations of biological and behavioral measures. That framing is consistent with current equine education efforts, which increasingly treat pain assessment as multidimensional rather than something likely to be solved by one lab value alone. (adelaide.edu.au)
Why it matters: For veterinary professionals, this study doesn’t change how EGUS is diagnosed today, but it does sharpen expectations. A blood test that fails to correlate with lesions is not ready to support treatment decisions, welfare assessments, or screening in practice. More importantly, the paper reinforces a point many equine clinicians already live with: gastric lesions, pain, performance effects, and pet parent-reported signs don’t line up neatly. That makes overinterpretation of nonspecific signs risky, particularly in horses with persistent problems that may involve glandular disease, management stressors, lameness-related pain, or other comorbidities. (cehhorsereport.vetmed.ucdavis.edu)
The study also lands in a clinical environment where practitioners are being asked to do more with imperfect tools. Educational resources from UC Davis emphasize forage access, feeding management, and veterinarian-guided treatment planning, while also warning that ulcers can recur quickly after treatment stops and that poor performance alone is a weak screening signal. In that context, a failed biomarker study is still useful intelligence: it argues against premature reliance on blood-based shortcuts and for continued emphasis on gastroscopy, case selection, management review, and careful follow-up. (cehhorsereport.vetmed.ucdavis.edu)
What to watch: The next phase will likely focus on larger validation studies, more horse-specific biomarker candidates, and composite approaches that pair biology with structured pain-behavior assessment. Until then, the practical standard remains the same: use gastroscopy to define lesions, and interpret suspected ulcer pain in the context of the whole horse. (adelaide.edu.au)