Study measures stress response in Lidia bulls at roping events
Bottom line
A new paper in Animals adds to the small but growing body of research on the physiology of Lidia bulls used in Spain’s “Toro de Cuerda,” or roping bull, celebrations. In the underlying 2025 study, researchers collected blood samples from 53 adult male Lidia bulls immediately before and after a standardized 45-minute running event across four Spanish autonomous regions, finding significant increases in leukocytes, red cell measures, platelets, muscle enzymes including creatine kinase, and the stress hormones cortisol and ACTH. The authors reported that, despite those marked acute changes, measured values remained within established bovine reference ranges. (sms.carm.es)
Why it matters: For veterinary professionals, the study doesn’t settle the welfare debate around roping bull events, but it does provide objective field data in an area where evidence has been limited. That matters because the discussion has largely been driven by ethics, tradition, and observational concerns, while prior veterinary commentary has pointed to overexertion and muscle injury risk in bulls subjected to intense, short-duration exertion. The new data may help inform event oversight, pre-participation screening, sampling protocols, and post-event monitoring, even as broader questions about whether “within reference range” equals acceptable welfare remain open. (sms.carm.es)
What to watch: Watch for follow-up work on which bulls are most vulnerable, including whether age, repeat participation, and timing of sampling meaningfully change the apparent physiologic burden. (pmc.ncbi.nlm.nih.gov)
A newly published Animals study is giving the veterinary field more concrete data on a long-disputed welfare issue: how Lidia bulls respond physiologically to Spain’s roping bull celebrations. In the 2025 paper, investigators measured pre- and post-event blood parameters in 53 adult male Lidia bulls after a standardized 45-minute running event and found significant acute changes in hematologic, biochemical, and endocrine markers associated with stress and exertion. The authors’ central conclusion was that the response was substantial, but still stayed within established bovine reference ranges. (sms.carm.es)
That matters because evidence on these events has been sparse, even though “Toro de Cuerda” celebrations are widely practiced in Spain and sit at the center of a broader cultural and welfare debate. The paper describes roping bull events as one of the country’s most widespread traditional bullfighting celebrations, and frames the work as the first detailed physiological assessment of Lidia cattle in this setting. More broadly, public scrutiny of bull-related spectacles has intensified in recent years, alongside declining support for bullfighting among younger Spaniards and continuing criticism from animal welfare groups and veterinary advocates. (sms.carm.es)
The study’s design was straightforward and field-based. Researchers sampled bulls 2 to 5 minutes before the event and again 2 to 5 minutes after completion, aiming to capture the acute physiologic response to continuous exercise. According to the publication, the bulls showed significant increases in leukocytes, lymphocytes, monocytes, eosinophils, neutrophils, erythrocytes, hematocrit, hemoglobin, and platelets, along with marked rises in lactate dehydrogenase, lactate, creatine kinase, cortisol, and ACTH. Creatine kinase rose as much as tenfold over baseline in the earlier paper from the same research line, underscoring the degree of muscle exertion involved. (sms.carm.es)
Still, the interpretation is more complicated than a simple “safe” or “unsafe” label. The authors emphasize that all measured parameters remained within normal bovine ranges, and present the findings as a basis for evidence-based welfare evaluation rather than proof of severe physiologic collapse. But that framing is likely to draw scrutiny. Prior veterinary commentary from the Spanish anti-bullfighting veterinary association AVATMA has argued that intense exertion in Lidia bulls can produce muscular lesions, enzyme release, hypoxia-related injury, and welfare compromise, particularly when events are prolonged. In other words, measurable adaptation and measurable harm aren’t mutually exclusive, and reference-range findings don’t necessarily resolve the welfare question. (sms.carm.es)
There’s also useful scientific context here. This 2025 Animals paper appears to be part of a broader line of work by the same group examining exercise-related physiology in Lidia cattle, including prior studies on biochemical variables after intense exercise and hormonal indicators linked to combative behavior. That suggests the field is moving, slowly, from anecdote and ideology toward repeatable physiologic measurement, even if the evidence base remains narrow and focused on acute biomarkers rather than longer-term outcomes such as recovery time, injury prevalence, or cumulative effects from repeat participation. (mdpi.com)
Why it matters: For veterinarians, the practical value is in risk stratification and event medicine. Acute spikes in cortisol, ACTH, CK, LDH, and blood cell indices can help define what “expected” looks like after these events, which may support more standardized pre-event exams, exclusion criteria for compromised animals, and post-event observation protocols. At the same time, the study highlights an important caution for welfare assessment: physiologic resilience should not be conflated with absence of distress. Veterinary professionals involved in policy, certification, or on-site oversight may need to weigh biomarker data alongside behavior, handling stress, transport, environmental conditions, event duration, and repeat exposure. (sms.carm.es)
What to watch: The next important step is the variability question flagged in the story’s title and abstract summary: whether age, prior participation, and sampling period explain why some bulls mount larger responses than others. If follow-on analyses show that older animals, repeat participants, or bulls sampled under different field conditions have consistently higher physiologic loads, that could shape welfare rules, veterinary screening standards, and the defensibility of these events under modern animal welfare expectations. (pmc.ncbi.nlm.nih.gov)