In this month's Science Corner, we look at more ways to ensure the equine athlete can reach their peak performance, from examining the relationships between sleep and cortisol levels, to whether a cool shower before working on a hot day can help stabilise a horse's physical condition.
Each month, we break down five recently published scientific studies that could affect the way we breed, train, and race Thoroughbreds. We explain what the research found and what it means for you.
You can click the title of each paper to read it in full.
1. Furosemide lowers circulatory system pressures to reduce EIPH incidence
What’s it about?
Furosemide (also known as Lasix) is a diuretic purported to assist with reducing the incidence of exercise-induced pulmonary haemorrhage (EIPH) in horses. This study examined the degree to which it achieved that and how pressure in the capillaries affects EIPH by looking at blood pressure during exercise before and after the use of furosemide.
Key findings:
Furosemide decreased mean pulmonary capillary, artery, and wedge pressures, as well as the minimum and maximum transmural pressures in the body’s circulatory system.
There was a significant decrease in EIPH score after using furosemide and a decrease in time spent with transmural pressure about the threshold established to cause EIPH, but did not stop it completely.
Furosemide | Image courtesy of The Horse
What it means for you:
This study backs up previous findings that furosemide lowers the chance of an EIPH episode by showing what pressures it reduces in the circulatory system. It is not a complete cure for the disease, but its use during track gallops can reduce the severity of an episode if a horse suffers from EIPH.
2. Cool showers before work help horses keep condition
What’s it about?
Working horses in hot countries can be difficult when trying to ensuring the horse doesn’t lose condition with work. This study looks at the effects of cooling a horse down prior to commencing exercise in a hot environment, and whether cooling measures could effect a horse’s weight and exercise tolerance.
Key findings:
Horses were either walked for 30 minutes, stood at rest for 30 minutes, or given a 10-minute cooling shower before work, and those that received the shower had a significant reduction in weight loss during work compared to the other two treatments.
There was no difference in heart rate and lactate during exercise, or in time to reach exhaustion, between any of the three treatments, but the pre-work walk resulted in significantly higher pulmonary artery temperatures.
A horse being hosed down | Image courtesy of The Horse
What it means for you:
A pre-work cool shower is a great method to reduce body condition lost by a horse working in a hot environment, and walking the horse for a long period of time before work leads to them getting hotter, which could potentially lead to a horse overheating. These are things to bear in mind when taking horses to hot race days during the Australian summer and early autumn.
3. Racehorses deemed high risk by sensors are more likely to suffer fatal injuries on the track
What’s it about?
This study looks back over sensor data collected from over 28,000 race starts completed by 11,000 American racehorses and examines the findings under a fresh light to work out if there is a correlation between a horse deemed high risk by a specifically trained algorithm and actual fatal musculoskeletal injuries occurring.
Key findings:
Horses deemed the highest risk by the algorithm were assigned six on a scale of one to six, and made up 0.4% of all race starts in the study, but also made up 4% of casualties identified by the study.
Horses rated six had a probability of suffering a fatal injury that was 44.6 times greater than horses rated one (lowest risk). Males were at higher risk than females, as were sprinters, but age was not a factor.
Horse racing | Image courtesy of The Image Is Everything
What it means for you:
It’s important for trainers and their staff to keep a close eye on their horses movement and any data they are receiving from wearable sensors, as it has become apparent that horses most often shows signs of being at high risk of injury long before the injury happens. Hopefully findings like these will drive technology in the direction of better pinpointing things that make a horse high risk.
4. Poor sleep associated with stress markers in racehorses
What’s it about?
This study aims to look at what the relationships are between racehorse’s sleep and markers that indicate their stress levels, and thus what this can inform us about their welfare.
Key findings:
Non-rapid eye movement sleep increased with age, while rapid eye movement decreased with age of the horse.
A higher frequency of abnormal behaviours was associated with poorer sleep quality, and horses with poor sleep quality had higher salivary cortisol levels in the morning.
Horse sleeping | Image courtesy of Horse Sports
What it means for you:
The quality of a horse’s sleep is another factor in their welfare, and needs to be considered by trainers. This study opens the door for further research into what causes poor sleep in racehorses and how to improve equine sleep quality.
5. Plasma proteins emerge as possible candidates for monitoring training
What’s it about?
This study aimed to identify new plasma protein biomarkers that indicate adaptation or overload caused by training in the hopes of expanding the toolkit for identifying how a horse is coping with its work.
Key findings:
Plasma samples collected at rest, immediately after exercise, and after recovery for horses in initial training showed widespread activation of inflammatory, metabolic, and antioxidant markers as horses adjusted to being in work.
For horses in mid-season conditioning, the plasma profile shifted to contain more proteins to do with remodelling and redox regulators, while samples taken around racing showed the strongest response from up to 100 different proteins.
What it means for you:
This study opens the door for further research into how to identify these proteins more easily at each stage and what the differences are in profiles when a horse is overloaded as opposed to working appropriately to improve in condition. In the future, these could be refined into similar simple stable-side tests such as lactate to help inform trainers how horses are progressing.
