In the silence between a horse and its pain lies one of veterinary medicine's oldest dilemmas: how to know what a creature cannot say. Researchers at Adelaide University tested whether blood-borne immune signals might serve as a proxy for suffering in horses with gastric ulcers — a condition found in nearly every racehorse — only to find the test could not distinguish the sick from the healthy. The failure is not a dead end but a clarification, narrowing the field of possibility and reminding us that understanding animal suffering demands methods as particular as the animals themselves.
Blood Test Fails to Detect Pain in Horses With Gastric Ulcers
Horses with gastric ulcers may suffer undetected pain due to lack of reliable diagnostic methods, affecting animal welfare particularly in the racing industry.
A horse cannot tell you where it hurts.
Mark
So the test measured immune cells from the blood. Why would that tell you anything about pain in the stomach?
Mimi
The idea is that pain and inflammation trigger immune responses throughout the body, including in circulating cells. If the stomach is inflamed, you'd expect to see that signal in the blood.
Luke
But the study found no correlation between the blood response and the presence of ulcers. That's a pretty clear negative result.
Mimi
Exactly. Only 25 percent of horses showed any response at all, and it didn't match up with who actually had ulcers.
Mark
What does that tell us? That the test is useless, or that the theory is wrong?
Mimi
Probably both, in a way. The researchers think the inflammation might be too localized to the stomach to show up in circulating blood cells.
Luke
So the test might be measuring the right thing—immune response—but in the wrong place. The stomach is walled off.
Mimi
That's the working hypothesis. Which means you'd need a different approach entirely.
Mark
Like what?
Mimi
They don't know yet. That's why they're calling for larger studies and horse-specific methods.
Luke
The real issue underneath this is that 92 percent of the horses in the study had ulcers. If the condition is that universal in racehorses, how do you even define what normal is?
Mimi
That's the welfare question. If nearly every racehorse has gastric lesions, are they all suffering? Some? None? We have no way to tell.
The Pulse
- Gastric ulcers afflict up to 100% of racehorses, yet veterinarians still have no reliable way to know which animals are actually in pain — treatment decisions rest on educated guesswork.
- A blood test measuring immune cell response, designed to detect inflammation linked to pain, failed to distinguish ulcer-affected horses from healthy ones in a 64-horse study.
- The near-total silence of the test — only 25% of horses showed any measurable immune response — suggests ulcer pain may be confined to stomach tissue and invisible to the bloodstream.
- Behavioral cues and facial pain scores offered no rescue, showing no meaningful correlation with the blood results and leaving veterinarians without a reliable observational fallback.
- Researchers are now calling for larger, horse-specific studies that combine biological markers with behavioral observation, treating this failure as a necessary step toward genuine diagnostic tools.
In the silence between a horse and its pain lies one of veterinary medicine's oldest dilemmas: how to know what a creature cannot say. Researchers at Adelaide University tested whether blood-borne immune signals might serve as a proxy for suffering in horses with gastric ulcers — a condition found in nearly every racehorse — only to find the test could not distinguish the sick from the healthy. The failure is not a dead end but a clarification, narrowing the field of possibility and reminding us that understanding animal suffering demands methods as particular as the animals themselves.
A horse cannot tell you where it hurts. This silence sits at the heart of veterinary medicine, and nowhere is it more consequential than with gastric ulcers — a condition so prevalent that some studies find it in nearly every racehorse in a stable.
Researchers at Adelaide University asked whether blood might speak where horses cannot. They collected samples from 77 horses and tested whether immune cells would produce interleukin-1 beta — a molecule linked to pain and inflammation — when exposed to triggers, and whether that response would differ between horses with ulcers and those without. The logic was sound. The results were not.
Of 64 horses that completed the study, 59 had gastric lesions — 92.2 percent. Yet only a quarter showed any measurable immune response, and that response bore no meaningful relationship to the presence of ulcers. The test could not tell a suffering horse from a healthy one. Behavioral cues and facial pain scores fared no better, offering no correlation with the blood findings.
Dr. Gustavo Ferlini Agne, who led the research, framed the outcome as useful rather than defeating. He noted that pain from ulcers may be localized to the stomach itself, invisible to circulating blood cells — a reminder that a blood test can only measure what reaches the bloodstream. The ulcer's suffering, if it exists, may never leave the tissue where it begins.
The racing industry faces an endemic problem without an objective solution. Lesions can be severe while outward signs remain subtle or absent, leaving treatment decisions — medication, dietary change, rest — grounded in uncertainty rather than evidence. Ferlini Agne called for larger studies and horse-specific methods that weave together biological markers and behavioral observation. For now, horses with gastric ulcers remain silent witnesses to their own condition, and those who care for them must still decide in the dark.
A horse cannot tell you where it hurts. It cannot say the pain is sharp or dull, constant or intermittent, bearable or unbearable. This silence is the central problem in veterinary medicine, and nowhere is it more consequential than with gastric ulcers—a condition so common in racehorses that some studies find it in nearly every animal in a stable.
Researchers at Adelaide University set out to solve part of this puzzle. If horses cannot speak their pain, perhaps their blood could. The team collected blood samples from 77 horses and tested whether immune cells in that blood might reveal something about gastric ulcers—specifically, whether those cells would produce a molecule called interleukin-1 beta, a substance linked to pain and inflammation in other species. The logic was sound: expose the cells to immune triggers, measure the response, and see if horses with ulcers showed a different pattern than those without.
The test failed. Of the 64 horses that completed the study, 59 had gastric lesions—a striking 92.2 percent. Yet only 25 percent of all horses showed any measurable response in the blood test. More damaging still, the researchers found no meaningful connection between that response and the actual presence of ulcers. The test could not reliably tell a sick horse from a healthy one. It could not distinguish pain from its absence.
Dr. Gustavo Ferlini Agne, who led the work, framed the failure not as defeat but as necessary information. "Horses can't tell us when they are in pain, and signs of discomfort can be subtle, inconsistent or easily overlooked," he said. The real problem runs deeper than any single test. Gastric ulcers present a diagnostic trap: a horse can have severe lesions and show almost no outward sign of suffering. Behavioral cues are unreliable. Facial pain scores—one of the few measurable indicators veterinarians have—showed no correlation with the blood test results. A horse might be in agony or merely uncomfortable, and a veterinarian would have no certain way to know.
The condition is endemic in racing. Studies have documented gastric disease in 80 to 100 percent of Thoroughbreds, depending on the form of the disease and the population studied. Yet the profession still lacks an objective measure of pain. Treatment decisions rest on guesswork. A veterinarian might recommend medication or dietary changes based on the presence of a lesion, but without knowing whether that lesion is actually causing suffering, the decision remains fundamentally uncertain.
Ferlini Agne was careful to note what the study did not prove: that gastric ulcers cause no pain. Rather, the findings suggest that pain or inflammation from ulcers may be localized to the stomach itself, invisible to the circulating immune cells in the bloodstream. A blood test, by its nature, measures only what reaches the blood. It may miss what is happening in the tissue where the ulcer actually exists.
The path forward requires both humility and ambition. Larger studies are needed. Horse-specific testing methods must be developed—approaches that combine biological markers with careful observation of pain-related behavior and signs of inflammation. The goal is not to replace veterinary judgment but to ground it in evidence. "Knowing what doesn't work is just as valuable as identifying a promising test," Ferlini Agne said. For now, horses with gastric ulcers remain largely silent witnesses to their own condition, and the veterinarians who care for them remain forced to make decisions in the dark.
Notable Quotes
Horses can't tell us when they are in pain, and signs of discomfort can be subtle, inconsistent or easily overlooked.— Dr. Gustavo Ferlini Agne, Adelaide University
Knowing what doesn't work is just as valuable as identifying a promising test.— Dr. Gustavo Ferlini Agne
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