The modern racehorse is a work of art. From their lung capacity, to their raw power, to the wonder that is the thoroughbred heart; these animals were born to run. When taking a closer look at the way a race horse’s body works, it’s no wonder how they can accomplish feats like winning the Kentucky Derby.
Looking to impress your friends with some awesome racehorse knowledge? Keep reading to discover some fascinating facts that will make you the star of the party on derby day!
A typical racehorse could need around 35,000 calories a day2, which is roughly twice as much as a regular horse in pasture! This means that a 1000-pound racehorse would need over 20 pounds of hay per day (at least!), plus a lot of added calories through concentrates like feed.
The exact feeding regimen may vary from trainer to trainer, but these high-calorie concentrates are usually a combination of fortified feeds, grains, and oats. To maintain energy levels and support the musculoskeletal system, racehorses require a balance of carbohydrates, proteins, and fats. However, races are short periods of high-intensity exercise that requires readily accessible energy from carbohydrates. As such, a racehorse’s diet will likely consistently have significantly higher starch levels than would be healthy for the average horse.
On non-race days, however, research supports lower starch and higher fat levels to prevent digestive issues and maintain steady energy levels. Plus, fat generally has twice as many calories as starch - a good way to get those calories with less volume.
Fats are also important for maintaining healthy skin and hair coats. Feeds like Bluebonnet’s Intensify® line are formulated with healthy fats and healthy fiber, to help decrease strain on the digestive system and promote performance.
A racehorse's ability to maximize its breaths, and take in enough oxygen, can be the deciding factor between powering down the homestretch or fatiguing before the finish line. Oxygen is required for the chemical reaction that turns glucose into energy. So a higher oxygen intake means more energy available to the muscles.
To put those numbers into perspective, a racing horse can move about 1,800 liters of air per minute5. The Kentucky Derby record time is 1:58 ⅖ , which means by the end of Saturday’s race - your top pick could have blown up a bundle of at least 250 balloons with the amount of air moving through its respiratory system!
⬇️ Nutrition that helps keep your horse’s lungs healthy and strong ⬇️
Inflammation reduction plays a key role in any animal’s ability to breathe properly. Through advancements in research - ingredients like the biologically active proteins in plasma and specific amino acids, have been shown to help reduce inflammation in the lungs. Plasma can be found in LIFELINE®+ Equine, as well as all Intensify® feeds.
Promote healthy alveolar-capillary pressure and oxygenation - when the oxygen we breathe in goes into our blood and travels to all the parts of our body to give us energy so we can do things like run! Solutions like Surge™ contain antioxidants, plus other natural ingredients like beet root powder, can help support these processes and keep your horse's lungs healthy.
During strenuous exercise such as racing, pressure increases inside the small blood vessels of the lungs. Exercise Induced Pulmonary Hemorrhage (EIPH) is a condition where horses experience bleeding in the lungs and airway when small vessels burst while active.
It is estimated that just .15-.84% of race starters in Thoroughbreds experience bleeding. Bleeding is graded from 0 - 4, with Grade 0 being the least severe, and 4 the most worrisome. Horses that were graded 4 were studied to be less likely to finish in the top 3 positions and, therefore, less likely to collect race earnings4.
In an effort to make racing a clean sport, the medicine Furosemide (commonly known as Lasix, and used to treat EIPH) was banned from many races, including all three Triple Crown events. Vets and researchers have cited concerns about its diuretic properties, increasing the potential risk for dehydration and adverse side-effects. For those that do still struggle with bleeding - it’s important to know there are nutritional approaches like the antioxidants found in Surge to help manage this disorder.
To learn more about how owners manage this problem through nutrition, read our Support for Bleeders blog.
Even before there was research to back it up, a Thoroughbred with a large heart has always been thought to be a winner. Heart size is believed to be largely influenced by the X chromosome - coining big hearts in racehorses as the “X-factor”.
Today, research has made some connections between race wins and a large heart capacity. But, bigger isn’t always better. Size also can increase with disease, like congestive heart failure - where hearts which become overly enlarged. This is not only detrimental to your horse’s health, but also makes the heart less efficient.
Secretariat’s heart was thought to be THREE TIMES the size of the average racehorse, at 22 pounds. That’s a large Thanksgiving turkey! It’s also 20% more than Secretariat’s rival, Sham, even though both horses measured 16.2 hands tall.
Comparatively - your heart weighs just half a pound, about the size of a large apple.
Circulation is key to heart function and delivery of oxygen-rich blood to hungry muscles. The nitric oxide in a horse’s body helps their tiny blood vessels, called capillaries, to stay strong and healthy. Supporting this normal function with nutrition, like that found in Surge™, means the blood can move around their body better, especially when they run fast.
Similar to how a car reaches its maximum speed, by revving its engine to increase its rpm, a race horse's heart rate increases to help it perform at its best during a race.
When a racehorse's heart beats faster, it can pump up to four times more blood - get more oxygen and nutrients to the muscles.
⬇️ Nutrition for a healthy horse heart ⬇️
To support a healthy heart rate, a horse's diet should include antioxidants like vitamin E and selenium, which can protect cells from damage and help maintain heart health. Many quality performance horse feeds will include such support in their guaranteed analysis.
Additionally, it's important to keep horses well hydrated, as dehydration can put stress on the heart by reducing blood volume, increasing heart rate and blood pressure, and making it harder for the heart to pump. Clean, fresh, water should always be available. During hot temperatures or strenuous exercise, most horses will require electrolyte supplementation to replenish key nutrients lost through sweat.
Thoroughbreds produce a lot of heat energy, around 1,250 kilojoules per minute 6 when they race, which is also enough to boil a liter of water!
While physiologically impressive, that level of energy output also puts racehorses at a higher risk for exertional heat illness (EHI). Exertional heat illness (EHI) is a type of heat stress that specifically occurs during intense physical activity. With a horse creating so much body heat, making hydration and cool-down procedures absolutely critical. EHI symptoms include dehydration, muscle cramps, and in severe cases, organ failure.
Research has shown that horses who have already experienced EHI are almost 19 times more likely to have it again. This same study of 702 racing horses with an occurrence of EHI, acclimation to warmer temperatures as a potential risk factor. if the weather leading up to a race was consistent, horses were slightly less likely to experience exertional heat illness.
To prevent EHI, proper hydration and cooling measures such as cold water baths and fans, should be provided to help regulate the horse's body temperature.
⬇️ Feeding to defend against heat stress ⬇️
Studies suggest that giving horses Chromium Propionate may help horses regulate their body temperature better, and decrease the chances of illnesses caused by heat stress, such as EHI.
Chromium Propionate is a mineral shown to help a horse turn glucose into energy more efficiently. As a result, less heat is produced during this process, to help the horse maintain a more stable body temperature during exercise. Chromium is approved for horses by the FDA, and can be given through feed or supplementation.
Studies have shown substantial weight long in racehorses during races and high-intensity exercise. One published in the Journal of Equine Veterinary Science, tracked changes in body weight and hydration status of racehorses during a simulated 1600-meter race (0.99 miles). The average Thoroughbred lost 2.8% of their bodyweight, while some horses lost up to 6.8%.
Multiple other studies 8,11 show similar ranges, citing averages closer to 5% and highest weight-loss up to 11%. That’s 50 to 110 pounds for the average 1000 lb racehorse!
While this is significant, don’t be too alarmed - the majority of the dropped weight is water loss through sweat. If the racehorse is hydrated, and in peak physical fitness, they should be able to regain the lost pounds within a couple days - some making a full recovery within 24 hours.
Even though most horses don’t exercise quite like these elite competitors, other stressors can have a similar impact. For example, research from the University of California, Davis has shown that horses can lose 0.45 to 0.55% of total body weight per hour of transport 10. That means your horse could lose over 30 pounds, during a 5-hour trip.
⬇️ Maximizing Hydration and Recovery ⬇️
Hydration starts long before the sweating begins. It is important to ensure horses are adequately hydrated before, during, and after travel or exercise.
Make sure your horse has access to clean water 24/7. Studies have shown that an average horse, NOT in work, drinks 5-7 gallons per day. However, under high temperatures, this same horse’s water intake could be more than 20 gallons per day X. This doesn’t even factor in exercise! ensure horses are adequately hydrated before, during, and after travel or exercise.
Whether your horses are turned out in the sunshine or running in a race, they will likely need a well-balanced electrolyte, ideally with sodium, chloride, and potassium. Research shows that added chromium propionate, magnesium, and calcium can also help with muscle recovery following exercise or heat stress.
Choose a solution that works best for your horse. A paste can make sure your horse gets the full dose if they’re picky, or during travel and competition. While a daily option is the most convenient to provide in their feed (or for horses who shun tubes).
Feeding a high-powered racehorse, for speed and good health, is certainly not a straightforward task. Providing the best diet for a racehorse requires a lot of knowledge and experience.
We hope you enjoy surprising your friends with these fun facts come race day! If you would like expert guidance on the nutrition for any of your horses, sign up for a FREE nutrition consult.
Direct Citations
1 - Evans, D. L., & Rose, R. J. (1997). A comparison of the size and shape of the equine heart in vivo and post mortem, with observations on the heart of the racing Thoroughbred. Journal of Anatomy, 191(2), 261-270.
2 - Geor RJ, Harris PA, Coenen M, et al. Energy intake and nutrient digestibility in thoroughbred horses during training and racing. Journal of Animal Science. 2001;79(11):2979-2988.
3 - Hermansen, R. J. (1985). The horse at high speed: A study of the maximum heart rate. Journal of Applied Physiology, 58(6), 1780-1786. doi: 10.1152/jappl.1985.58.6.1780.
4 - Lester, G. D., Secombe, C. J., & Perkins, N. R. (2017). EIPH in horses: prevalence, impact, and management strategies. Journal of Equine Veterinary Science, 52, 9-19.
5 - Mazan M. Equine exercise physiology-challenges to the respiratory system. Anim Front. 2022 Jun 14;12(3):15-24. doi: 10.1093/af/vfac035. PMID: 35711503; PMCID: PMC9197307.
6 - McGowan, C.M., Davies-Morel, M.C., Evans, D.L., Hodgson, D.R., & Rose, R.J. (2010). Metabolic rate, oxygen consumption and carbon dioxide production in Thoroughbred horses during incremental treadmill exercise. Equine Veterinary Journal, 42(S38), 148-153. doi: 10.1111/j.2042-3306.2010.00293.x.
7 - McKeever, K. H., Martin, B. B., & Straub, R. (2013). Changes in body weight and hydration status of Thoroughbred racehorses during a simulated 1600-meter race. Journal of Equine Veterinary Science, 33(11), 920-926.
8 - Montain, S. J., & Coyle, E. F. (1998). Fluid and electrolyte losses during exercise in the heat: sweat rates and gut losses. Journal of Applied Physiology, 70(1), 157-163.
9 - Reef, V. B., B. T. Spencer, L. H. Stoltz, L. W. Adams, and E. B. Farris. ""Heart weight and left ventricular dimensions of Thoroughbred, Standardbred, and Quarter Horses."" Journal of the American Veterinary Medical Association 198, no. 11 (1991): 1982-1986.
10 - Stull CL, Rodiek AV. Physiological responses of horses to 24 hours of transportation using a commercial van during summer conditions. J Anim Sci. 2000 Jun;78(6):1458-66. doi: 10.2527/2000.7861458x. PMID: 10875627.
11 - Ungerfeld, R., Correa, M. N., & Johnson, C. B. (2000). Effects of an electrolyte supplement on fluid and electrolyte balance and running capacity in Standardbred horses. Journal of Animal Science, 78(7), 1818-1825.
Additional References
12 - Arthur RM. Respiratory problems in the racehorse. Vet Clin North Am Equine Pract. 1990 Apr;6(1):179-96. doi: 10.1016/s0749-0739(17)30562-x. PMID: 2187569.
13 - Bayly, W. M., & Van Der Heyden, M. A. (1997). Left ventricular mass and dimensions in Thoroughbred racehorses. American Journal of Veterinary Research, 58(7), 738-742.
14 - Butler PJ, Woakes AJ, Smale K, Roberts CA, Hillidge CJ, Snow DH, Marlin DJ. Respiratory and cardiovascular adjustments during exercise of increasing intensity and during recovery in thoroughbred racehorses. J Exp Biol. 1993 Jun;179:159-80. doi: 10.1242/jeb.179.1.159. PMID: 8340728.
15 - Pagan, J. D., Horn, G. W., Holt, T. N., Fontenot, J. P., and Johnson, D. D. (2013). Effects of plasma protein supplementation on growth performance, health, and immune responses of weanling horses. Journal of Animal Science, 91(7), 3152-3161.
16 - Sakamoto, K., Gunawan, A., Asano, K., Sato, F., and Katoh, K. (2017). Effects of dietary plasma protein on respiratory function in weanling horses. Journal of Equine Veterinary Science, 51, 15-19. DOI: https://doi.org/10.1016/j.jevs.2017.01.006
17 - Hoffman, R. M., & Holcomb, K. E. (2009). Water intake of horses increases under high environmental temperatures. Journal of animal physiology and animal nutrition, 93(1), 71-77.
