AgriFutures Australia's Science Corner Summarizes Recent Equine Research

AgriFutures Australia's Science Corner brings to light recent equine research with direct implications for the thoroughbred industry. This month's edition highlights five key studies impacting breeding, training, and racing Thoroughbreds, focusing on areas like performance, health, and injury prevention.

Furosemide Lowers Circulatory System Pressures to Reduce EIPH Incidence

This study delved into how furosemide (Lasix), a commonly used diuretic, mitigates exercise-induced pulmonary haemorrhage (EIPH) by analyzing blood pressure dynamics during exercise, both before and after its administration.

The research revealed that furosemide significantly decreased mean pulmonary capillary, artery, and wedge pressures. It also reduced minimum and maximum transmural pressures within the circulatory system. Crucially, a significant decrease in EIPH score was observed after furosemide use, with less time spent with transmural pressure exceeding the known EIPH-triggering threshold.

While not a complete preventative, furosemide reduces the severity and incidence of EIPH episodes by lowering circulatory system pressures during track gallops.

This reinforces prior findings regarding furosemide's effectiveness in reducing the likelihood of EIPH episodes.

Cool Showers Before Work Help Horses Maintain Condition

Research explored the impact of pre-exercise cooling on horses operating in hot environments, specifically concerning weight management and exercise tolerance. Horses were divided into three preparatory groups: a 30-minute walk, 30 minutes of rest, or a 10-minute cooling shower before work.

Horses that received the pre-work shower exhibited a significant reduction in weight loss during exercise compared to the other two groups. While heart rate, lactate levels during exercise, and time to exhaustion showed no significant difference across treatments, the group that undertook a pre-work walk had notably higher pulmonary artery temperatures.

A pre-work cool shower effectively reduces body condition loss in horses working in hot conditions. Conversely, prolonged walking before exercise may inadvertently contribute to overheating.

Racehorses Deemed High Risk by Sensors More Likely to Suffer Fatal Injuries

A retrospective study analyzed an extensive dataset of sensor information from over 28,000 race starts, involving 11,000 American racehorses. The goal was to identify correlations between algorithmic risk assessment and fatal musculoskeletal injuries.

Horses classified as highest risk (level six on a scale of one to six) represented a mere 0.4% of all race starts, yet accounted for a disproportionate 4% of all casualties. Those rated at level six had a staggering 44.6 times greater probability of suffering a fatal injury compared to horses rated at level one (lowest risk).

This research underscores the critical importance of monitoring horse movement and sensor data, as crucial signs of high injury risk often manifest before an injury occurs.

The study also identified male horses and sprinters as being at higher risk, while age did not emerge as a significant factor in injury probability.

Poor Sleep Associated with Stress Markers in Racehorses

This study investigated the intricate relationship between racehorse sleep patterns and indicators of stress, providing insights for welfare considerations. The findings revealed that non-rapid eye movement sleep increased with age, whereas rapid eye movement sleep decreased with age.

A higher frequency of abnormal behaviors was directly linked to poorer sleep quality. Furthermore, horses experiencing poor sleep quality consistently exhibited higher morning salivary cortisol levels.

Equine sleep quality is a vital welfare factor. These findings highlight an urgent need for further research into the underlying causes of poor sleep in racehorses and the development of effective improvement methods.

Plasma Proteins Emerge as Possible Candidates for Monitoring Training

This research aimed to identify novel plasma protein biomarkers that could signal training adaptation or overload, thereby expanding the toolkit for assessing a horse's response to work. Plasma samples were collected at various stages: at rest, immediately after exercise, and after recovery, from horses undergoing initial training, mid-season conditioning, and around racing events.

During initial training, the study observed widespread activation of inflammatory, metabolic, and antioxidant markers as horses adjusted to their new workload. In mid-season conditioning, the plasma protein profile evolved, showing a shift to include more proteins related to remodelling and redox regulators. The samples collected around racing events exhibited the strongest response, involving up to 100 different proteins.

This study paves the way for identifying easily detectable plasma proteins at each training stage, potentially leading to simple, stable-side tests, similar to lactate tests, to help trainers monitor horse progression and preemptively identify overload.