Because horses can lose up to 10–15 litres of water an hour, much more than their human counterparts, simply drinking water after exercise is not enough. Riders know first-hand the damaging effects that can result from dehydration, a condition when sweating exceeds water consumption. We’ve all used a skin pinch test to assess hydration in our horses. University of Guelph professor, Dr. Mike Lindinger, cautions this qualitative approach may be “too little, too late.”
Why? Clinical dehydration may already be occurring when skin tenting is apparent.
Consequences of dehydration can be as serious as lack of appetite, colic, physical injury, heat strain, hyperthermia, cardiovascular impairment, kidney damage, and even death.
“Drinking plenty of water after exercise is NOT enough!” Dr. Lindinger stresses. Water given during or after exercise dilutes the body fluid compartments and is excreted because the body senses it as volume overload. Prolonged exercise results in loss of electrolytes and depleted glycogen levels which contribute to muscle soreness and poor performance. Simply replacing water is not sufficient due to the high concentration of electrolytes (including sodium, potassium, chloride, magnesium and calcium) that a horse loses during sweating. Administration of electrolytes helps restore those essential nutrients lost during sweating.
Dr. Lindinger first became involved with studying electrolyte balance in horses 20 years ago after meeting potential MSc student Gayle Ecker, current director of Equine Guelph. Ecker introduced Lindinger to elite equine athletes in the world of endurance riding and eventing.
In a scientific study, Lindinger and Ecker monitored the performance of horses on a treadmill with and without use of an electrolyte supplement. When horses received electrolyte supplement one hour before exercise the horses could perform at a fast trot for 27% longer duration than the control group.
Their research also measured the rate of gastric emptying and intestinal absorption into the blood. Gamma camera imaging was used to track gastric emptying and showed the electrolyte supplement emptied from the stomach as quickly as water. Through blood testing it was discovered the supplement, given one hour prior to exercise, was being absorbed into the blood within 10 minutes of administration. Muscle biopsies showed that potassium was taken up by this tissue, and sweat analysis showed appearance of sodium from the supplement, indicating that supplemented electrolytes replace those lost through sweating. Electrolytes moderate many body functions including firing of nerves and contracting of muscles.
Dr. Lindinger’s studies have included working with three-day event horses and endurance horses (most notably before the games in Atlanta) but high performance horses are not the only ones at risk for dehydration. Transport stress can also result in dehydration. Lindinger says one of the first signs of dehydration is usually behavioural, as the horse becomes less responsive. His studies conclude that giving electrolytes before situations likely to cause dehydration will be beneficial to overall performance and help guard against the serious effects of dehydration.
Jackie Bellamy, Communications and Administration assistant at Equine Guelph, has 20 years of equine experience including training, coaching, competing and writing for equestrian magazines. Her “ Biosecurity for Horse Farms ” appeared in the April/May 2013 edition of Holistic Horse (Issue 84).
Funding for Dr. Lindinger’s research was provided by the American Endurance Rider’s Conference, Buckeye Nutrition, Equine Guelph, Natural Sciences and Engineering Research Council of Canada, Ontario Ministry of Agriculture, Food and Rural Affairs and United States Equestrian Federation Equine Health Research Fund. Buckeye Nutrition produced the electrolyte supplement used in the scientific testing.
Reprinted by kind permission of Equine Guelph, www.equineguelph.ca