What are electrolytes?
Present in small amounts, electrolytes are positively charged ions that are dissolved in the blood and the fluid that exists between cells and sweat. The principal electrolytes are sodium, potassium, chloride, calcium and magnesium.
How do horses get their electrolytes?
Most horses receive most of their daily electrolytes from forage. Calcium and phosphorus are also commonly added to compound feeds and mixes. However salt can be low in forages and are not added in high levels into compounds. Hence extra salt is routinely offered as licks or in the feed.
Horses on low forage diets, such as those receiving a lot of hard feed, or those on restricted diets due to being good-doers, will have a lower electrolyte supply than horses with good fibre levels in their diet.
Many working horses receive added electrolytes as a supplemented to their diet.
Why are electrolytes important?
Electrolytes are responsible for the correct function of nerves and muscles. They also help maintain normal hydration and are integral in maintaining the functioning of the digestive system, and the other vital organs.
Sub-optimal electrolyte status can lead to muscle problems and poor performance. Since electrolytes cannot be stored in the body, the amount available to the horse is dependent on electrolyte intake compared to natural losses through sweat, urine and faeces.
Electrolytes and sweating
Sweating removes heat generated by muscles during exercise. A fit horse efficiently removes heat from where it is not wanted in the muscles, out to the skin where it is lost through sweat- where the process of evaporation from the skin cools the horse.
Equine sweat is hypertonic – that it is contains more salts than internal body fluids – which means that a sweating horse loses electrolytes as well as water. Typically a working horse can lose 7-8 litres in an exercise bout. The amount of sweat produced by an individual depends on temperature, workload, temperament and stage of fitness.
One litre of horse sweat contains around 3.5g of sodium, 6g of chloride, 1.2g of potassium and 0.1g of calcium
I litre of sweat is estimated to dissipate heat from 1 –2 minutes of extreme work or about 5 minutes of sub-maximal work, summer or winter
When do horses need extra electrolytes?
- Whenever a horse works hard, summer or winter.
- Electrolyte use in the days before a competition will stimulate water intake such that the horse enters the competition fully hydrated. (long term mega-dosing is wasteful as any excesses cannot be stored)
- Before during or after travelling: offering water or an isotonic solution every couple of hours on long journeys should help avoid unnecessary fluid* and/or electrolyte deficits before the competition has begun.
- Before and during moderate to intense work: Research has shown that correct administration of good quality electrolytes can increase the time it take for a horse to fatigue by nearly 23%. (On the day of competition or exercise bout, the final offer of electrolytes should be made together with water, at least 4 hours before exercise.)
- Horses on low or restricted forage diets (i.e. less than 30% of total diet as forage) will receive a diet inherently low in electrolytes.. Equally a new forage source could be markedly different to the previous source, and cause problems.