Pagan.J.D. 2001. Electrolytes and the Endurance Horse.
– Endurance World.
Geor, R.J. 2002. Fluids and Electrolytes Keeping pace with losses.
– Equine Health Update.
Electrolytes are substances that dissociate in solution into electrically charged particles called ions. In the horse, electrolytes play an important role in maintaining osmotic pressure, fluid balance and nerve and muscle activity. During exercise, sodium (Na+), potassium (K+), chloride (Cl-) and magnesium (Mg++) are lost in the sweat and urine. Loss of these electrolytes causes fatigue and muscle weakness, and decreases the thirst response to dehydration.
It is important to have some idea of the magnitude of loss of electrolytes from the horse during exercise before a supplementation programme can be developed to replace these losses. Since most of the electrolyte loss in the horse occurs through sweating, one method of calculating electrolyte requirements can be based on different amounts of sweat loss. Body weight loss during exercise is a good way to estimate the amount of fluid lost, where 1 kg of body weight loss equals 1 litre of fluid.
The Composition table (above) contains the levels of Na+, Cl-, K+and Mg++ required per day by a horse at rest and after exercising hard enough to lose either 5, 10, 25 or 40 litres of sweat. The amount of fluid loss will depend on a number of factors such as duration and intensity of exercise, temperature and humidity. Therefore, the best way to determine this is to weigh the horse before and after exercise. This after exercise weight should be taken before the horse is allowed to drink. A racehorse training in Durban will obviously lose more sweat than one training in Iceland, but for the sake of comparison we will consider that during a routine workout, sweat loss in a race horse will amount to between 5 and 10 litres.
Losses of 25 litres might occur during a normal endurance ride, and 40 litres of fluid loss would probably only be seen in an exhausted, dehydrated endurance horse in serious danger of dying.
Many people don’t have a good idea of their horse’s daily sweat loss or don’t have access to a scale to weigh their horse before and after exercise. Therefore, a more general set of recommendations based on work intensity can be used. Table A contains daily requirements of electrolytes for a 500 kg horse at maintenance and at light, moderate and heavy work. These values were calculated by Dr Helmet Meyer, a German researcher who has extensively studied electrolyte requirements in horses (grams/day).
Table A: Daily requirements of sodium, potassium, chloride and magnesium for horses exercising at different intensities.
The following are general guidelines for Rigly Endurance Paste. The actual amount of electrolyte supplementation will depend on the level of exercise, temperature and humidity.
Light training = 30 ml Rigly Endurance Paste / day
Moderate training = 60ml – 90 ml Rigly Endurance Paste / day
Heavy training = 90ml – 120 ml Rigly Endurance Paste / day
Recognising the relatively extensive sweat loss during a race, an endurance horse should receive the following before and during a competition:
- Night before = 60 ml Rigly Endurance Paste
- Prior to start of race = 60 ml Rigly Endurance Paste
- Every vet check = 30ml – 60 ml Rigly Endurance Paste
Large volumes should not be administered to horses that have suffered acute water deprivation.
Warnings / Precautions:
Ensure a separate supply of clean, fresh drinking water is also available after administering the required amount of paste.
Store below 30 oC. (Room Temperature). Protect from freezing. Replace cap tightly after use.