Study into early detection of injury risk

Racing Australia’s Research and Development Fund, in collaboration with the Equine Genetics
Research Centre (EGRC) and Telemedvet, has announced a joint investment exceeding $400,000 for a 12-month project aimed at studying a serum biomarker in the clinical investigation of equine musculoskeletal injuries. This initiative has the potential to develop real-time capabilities that could help prevent injuries to both horses and jockeys.

The project focuses on evaluating the serum bone biomarker Osteocalcin (OC) as a potential predictor of equine lameness and fractures. Dr. Natasha Hamilton, a leading global equine geneticist and Director of the EGRC, highlights the significance of this research:

“Pilot studies have shown a correlation between OC level and abnormal radiomic scintigram findings that can indicate a horse is at elevated risk of catastrophic fracture. This study will investigate whether OC is an effective biomarker to identify at risk horses in a broader population. We are very excited to be able to support this work.”

The research is led by Prof. Dominique Blache from the University of Western Australia’s School of Agriculture and Environment, alongside a team of co-investigators headed by Dr. Peter Tually, Co-director and Nuclear Medicine Practitioner at Telemedvet. Dr. Tually envisions integrating advanced nuclear technology into Thoroughbred welfare practices:

“Our passion for horse racing and a lifelong dedication to science and advanced imaging has given us a unique perspective. The support of trainers has been essential and has shown us the enthusiasm the industry has for modern advancements. To be supported by the regulators in this important research is something we are immensely proud of.”

The Racing Australia Research and Development Fund is supported by industry contributions, with $20 from every Thoroughbred registration allocated to its investment initiatives. All research projects undergo rigorous assessment in alignment with Racing Australia’s commitment to horse welfare. Racing Australia CEO Paul Eriksson reinforces this dedication:

“Racing Australia has a national role and firm commitment to advance research and development to enhance and support positive welfare outcomes for athletes both human and horse. The Racing Australia Research and Development Fund and the EGRC led by Dr Natasha Hamilton is excited to invest in research that takes steps in assessing the risk of fractures to mitigate injuries and support trainers in managing the training schedules of their equine athletes.”

(edited press release)

Cardiac Arrhythmias and the Role of cTnI in Horses

While some arrhythmias in horses are benign and pose no significant health risks, others can
severely impact performance and, in some cases, become life-threatening. Accurate diagnosis and management are especially critical in performance horses, where cardiac efficiency directly affects athletic ability.

Unlike humans, where vascular disease can lead to heart attacks, such conditions are rare in horses. Instead, horses are more commonly affected by cardiac rhythm abnormalities (arrhythmias). The most frequent arrhythmia observed is atrial fibrillation, which can impair heart function but is often manageable.

More serious are ventricular arrhythmias—abnormal heart rhythms originating from the ventricles—which can lead to severe cardiac complications. Horses with myocardial toxicities often experience these arrhythmias, but because they tend to be intermittent, detection can be challenging.

In human medicine, cardiac damage is assessed using cardiac troponin-I (cTnI), a regulatory protein released into the bloodstream when myocardial (heart muscle) cells are damaged. cTnI is highly specific to cardiac muscle and plays a crucial role in heart contraction. Elevated plasma cTnI levels are widely used to diagnose and assess the severity of myocardial damage, particularly in coronary artery disease (commonly associated with heart attacks).

Since equine cTnI is structurally similar to human cTnI, diagnostic methods developed for humans have been adapted for use in horses. 

Researchers, led by Jonathan Foreman, at the University of Illinois Veterinary Teaching Hospital, conducted a study to establish reference values for cTnI in healthy horses, using a human chemiluminescence assay. They then compared these values to cTnI levels in horses with diagnosed cardiac disease, confirmed through electrocardiography (ECG) and ultrasonography. All full report of the work is published in Animals.

The researchers found that horses with atrial fibrillation sometimes showed mildly elevated cTnI levels, occasionally falling outside the normal reference range.

On the other hand, horses with ventricular arrhythmias had a 10-fold higher median cTnI concentration compared to those with atrial fibrillation.

These results suggest that measuring plasma cTnI levels could be a valuable diagnostic tool in horses with suspected ventricular premature contractions or ventricular tachycardia. The findings support the use of cTnI assays in equine medicine to detect and monitor cardiac disease, improving early diagnosis and management of potentially serious conditions.

For more details, see:

Jonathan H Foreman, Brett S Tennent-Brown,  Mark A Oyama,  D David Sisson. 

Plasma Cardiac Troponin-I Concentration in Normal Horses and in Horses with Cardiac Abnormalities

Animals (Basel) (2025);15(1):92. 

doi: 10.3390/ani15010092

Anatomy workshop

(c) Lifeontheside Dreamtime.com

If you’d like to expand your knowledge of horse anatomy, you might be interested in a three-day dissection workshop hosted by Gillian Higgins of Horses Inside Out at Equine Science Labs, Hartpury University, (Gloucester UK) on April 9th, 10th, and 11th, 2025.

You can choose to attend all three days for a comprehensive whole-horse dissection or select specific days based on your interests. Each day focuses on a different area: Spine, Head & Neck, and Limbs. This hands-on workshop offers a unique opportunity to learn in a professional, clinical lab environment.

Full details are available at:

https://www.horsesinsideout.com/dissection-workshop

Impact of environmental exposure and captivity on gut microbial diversity

Petrą Kaczensky Wikipedia CC-BY-SA3.0

Over thousands of years, hosts and their resident microbiota have evolved complex interactions, with microbial communities adapting to the physiological and dietary conditions of their hosts. 

In addition to these evolutionary relationships, genetic factors play a crucial role in shaping microbial colonisation and immune responses. Domestication significantly influences microbiome composition through changes in diet, habitat, and human-driven selection pressures. The external environment also contributes to microbial diversity, as hosts acquire microbes from soil, water, and food sources. 

A study conducted by Victor Hugo Jarquín-Díaz and colleagues, and published in Scientific Reports, explored the contribution of environmental microbiota from freshwater sources to the gastrointestinal microbiomes of wild khulans (Equus hemionus hemionus). 

 The study also compared the faecal microbial diversity of wild khulans to that of captive khulans in Europe and two other equid species—Przewalski’s horses and domestic horses—in Mongolia. By examining these populations, the researchers sought to understand the extent to which environmental exposure and captivity shape equid gut microbiota. 

They used PacBio sequencing (a DNA sequencing technique widely used for microbial genomics) and the LotuS pipeline for 16S rRNA gene sequencing, enabling a detailed analysis of microbial communities. The research team measured alpha diversity (species richness and evenness within a sample) and beta diversity (differences between samples) and conducted differential abundance analysis to identify microbial differences between groups. 

Their findings showed minimal microbial exchange between wild khulans and their water sources, suggesting that freshwater sources have little impact on their gut microbiomes. They point out that this finding also indicates that khulans contribute little to waterborne microbial contamination, despite regular interactions with these water sources. 

 Comparisons revealed that wild khulans have a more diverse and richer gut microbiome than captive khulans. The researchers suggest that this is an adaptation to the harsh nutritional conditions of the Gobi Desert, where wild khulans must digest a wide range of fibrous, low-quality forage. In contrast, captive khulans have reduced microbial diversity, likely due to changes in diet, lower exposure to environmental microbes, and possible antibiotic use. 

They conclude that their findings demonstrate limited microbial sharing between khulans and the waterholes they drink from, challenging the hypothesis that these act as a source of their gut bacteria or that khulans shape the water microbiome through their exudates. Captive khulans exhibit lower microbial diversity compared to their wild counterpart. However, captivity appears to be less of an influence than species differences – as the faecal biomes of captive and wild khulans are more like each other than they are to those of domestic horses and Przewalski’s horses. 

For more details, see: 

 Jarquín-Díaz, V.H., Dayaram, A., Soilemetzidou, E.S. et al. 

 Unraveling the distinctive gut microbiome of khulans (Equus hemionus hemionus) in comparison to their drinking water and closely related equids. 

 Sci Rep (2025)15, 2767 (2025). 

 https://doi.org/10.1038/s41598-025-87216-z

Behavioural signs of gastric pain

(c) Abby Thoriaty Dreamstime

 Researchers have identified distinctive behavioural signs that may indicate equine gastric discomfort.

Gastric ulcers are often believed to be the cause of a wide range of behavioural and performance issues in horses. Studies suggest that between 60% and 80% of horses across various disciplines experience gastric ulceration. However, a definitive diagnosis requires gastroscopy.

Are there specific behavioural indicators that reliably suggest gastric ulceration? Researchers at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center believe so.

In research published in Animals, Catherine Torcivia and Sue M. McDonnell explored this question. As part of their clinical assessments, they regularly analyse 24-hour video recordings of hospitalised horses to detect subtle signs of discomfort, or intermittent signs caused by heart or neurological problems, which might otherwise go unnoticed. Over the years, they suspected that certain behaviours were associated with gastric disease.

Their findings suggest that specific discomfort behaviours are strongly linked to gastric disease. These behaviours include frequent attention to the cranial abdomen—such as nuzzling, swatting, nipping, and/or a focused gaze on the abdomen caudal to the elbow—as well as deep abdominal stretching. These signs were often observed while horses were eating, drinking, or anticipating feeding.

To investigate this further, they conducted a study to evaluate how reliably these behaviours correlated with gastric disease. They reviewed clinical records of 30 cases where 24-hour video behaviour evaluations had been conducted alongside gastroscopic examinations.

Of the 30 horses studied, 26 were diagnosed with gastric disease—either gastric ulcers or gastric impaction. Gastric discomfort behaviours were observed in 24 of these 26 horses but were absent in all four horses without gastric disease. Among the six horses that did not display these behaviours, four had no abnormalities on gastroscopy, while two exhibited only mild lesions.

The researchers conclude that, although a larger study is needed to accurately estimate the sensitivity and specificity of these behavioural associations with gastric disease, the findings support their long-held clinical impression that gastric discomfort in horses has a recognisable behavioural signature.

For more details, see:

 

Torcivia, Catherine, and Sue M. McDonnell. 2025. 

Behavioral Signature of Equine Gastric Discomfort? Preliminary Retrospective Clinical Observations

Animals (2025) 15, no. 1: 88. 

https://doi.org/10.3390/ani15010088

Assessing dental pain : limitations of the Horse Grimace Score

(c) Chelle129 Dreamstime.com

Research suggests that the Horse Grimace Score may not be a reliable tool for objectively assessing dental pain in
horses. 

 The Horse Grimace Score (HGS) is a facial expression-based pain assessment tool that evaluates specific facial changes, including: ears held stiffly backward, orbital tightening, glazed or withdrawn expression, tightening of the mouth and lips, strained nostrils, increased facial muscle tension.

 

While it has been successfully used for evaluating pain associated with lameness and colic, its effectiveness in detecting dental pain remains uncertain.

 

Dental disease is a common issue in horses, with conditions such as equine odontoclastic tooth resorption and hypercementosis (EOTRH) and equine periodontal disease (PD) being recognised as painful. 

 

Given the importance of accurately assessing pain, a small study was conducted to evaluate and compare the usefulness of the Horse Grimace Score and a numerical rating scale (NRS) for assessing dental pain in horses with dental conditions.

 

The study, by Amelia Sidwell and colleagues at the University of Nottingham veterinary school in conjunction with the Pool House Equine Hospital aimed to see if a pain scale based on facial expressions (HGS) provided an objective assessment of pain in equine dental cases. 

 

An additional aim was to identify whether specific dental conditions are associated with greater pain severity. A full report of the research is published in the Veterinary Record.

 

Twelve horses that had been admitted to a referral equine referral hospital for tooth extraction were included in the study. Diagnoses included: cheek tooth fracture (5 cases), periapical tooth infection (3), developmental disorders (2), periodontal disease (PD) (1), EOTRH (1).

 

Each case was assessed for pain by an experienced clinician using both a HGS and a numerical rating score. In addition, photographs of the head showing facial expressions were incorporated into a questionnaire which was submitted to equine veterinary surgeons, nurses, and final-year veterinary students for evaluation.

 

The research team found that there was poor correlation between individual observers using both pain scales, suggesting low reliability in assessing dental pain. The highest mean pain scores were associated with periodontal disease and EOTRH, aligning with existing literature on the painful nature of these conditions.

 

They concluded that tools designed for identifying acute pain (such as HGS) are unreliable for assessing chronic pain like dental pain. They recommended the development of a dental-specific ethogram to more accurately assess dental pain in horses.

 

 

For more details, see:

 

Sidwell AE, Duz M, Hill B, Freeman S, Hole SL. 

Application of the horse grimace scale in horses with dental disease: Preliminary findings. 

Veterinary Record. (2025) 196(3):e4800. 

https://doi.org/10.1002/vetr.4800