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Does my horse need electrolytes?

Electrolytes are essential minerals found in the body and lost in sweat, urine and breath. Within the body they are needed for hydration, regulation of blood acidity, absorption of nutrients from the digestive tract, nerve function and muscle function.

Electrolytes should not be thought of as a supplement, instead they are a vital and basic component of any horse’s diet, especially if they are exercised.

What do electrolytes do in the body?

Sodium and Chloride: are essential for maintaining water balance, which is needed for cell function and acid base balance. Sodium deficiency is not uncommon, and typically presents as poor performance. Chloride deficiency is less common unless extreme prolonged sweating has occurred.

Potassium: is also required for cell function and acid base balance. Potassium is found in significant amounts in forages, so deficiency is less common. However, it is worth remembering that after strenuous exercise, the horse may not eat normal quantities of forage, and choose to rest instead. There is no body “store” for sodium, chloride or potassium so losses must be accounted for after exercise.

Calcium and Magnesium: Requirements for these ions increases with workload, but the increase in requirements is not down to sweat loss alone, they are needed for muscle function, lactate trapping and bone turnover. They are stored in bone, but accessing to the store is slow.

Where do electrolytes come from in the diet?

Electrolytes occur naturally in the horse’s diet. However, modern pastures and forages are commonly low in sodium and as a result it is recommended that salt (sodium chloride) is offered to all horses, even those who are retired or resting. This is commonly done in the form of a salt lick, as many retired or resting horses are not fed bowl feeds on a daily basis. Salt licks as a sole source of sodium are not recommended for horses in exercise, as just like us, some horses don’t like the taste and do not use them even if they need to.

The concentration of calcium and magnesium in grass and forage will vary enormously depending on the species in the pasture and the time of year. Young exercising horses are at greater risk of deficiency in the diet, while special attention should be paid to the diets of mature horses with muscle problems. The easiest way to ensure the diet is balanced for calcium and magnesium is to feed label directed volumes of a hard feed or pelleted balancer, and then top up with a complete electrolyte if the horse is sweating regularly.

To help develop a better understanding of electrolyte requirements, a knowledge of the amount of sweat lost while exercising and the amount of electrolytes per liter of sweat is really useful.

How much sweat does my horse loose?

Sweat loss can be measured quite accurately if you are able to weigh your horse (plus any droppings and urine passed) before and after exercise, once he has dried off. However, this is a luxury which the majority of riders do not have.

Instead approximations can be made by assessing how hard a horse has worked, and how long worked for. The NRC described moderate work load as 3-5hr/week mainly at trot, with some canter, hard work as 4-5hr/week mainly at canter. The electrolyte requirements of the exercising horse increase dramatically compared to their resting counterparts, as shown in the table below.

Workload Sodium (g) Chloride (g) Potassium (g) Calcium (g) Magnesium (g)
Resting 10 40 25 20 8
Moderate 18 53 32 35 12
Heavy 26 67 39 40 15


(Information taken from the NRC for a 500kg horse. Moderate work load equates to 3-5hr/wk, Heavy work load equates to 4-5hr/wk)

A really important point to consider is temperature, which is not accounted for in this table. Hot weather will markedly increase sweat production and therefore, electrolyte losses.

A horse exercising in warm conditions, for an hour can easily loose 5L of sweat, equating to 50g of electrolytes. These horses tend to require sponging off under their saddle, over their neck and flanks and between their legs.

At the most extreme end of the scale would be the horse which is dripping sweat, this horse could be loosing approximately 18L of sweat per hour, requiring 180g of electrolytes to replace what has been lost. Remember, the body does not have a rapid release store of electrolytes, so sweat losses need to be replaced after exercise.

In the majority of cases, following label directions on complete electrolyte products will provide ample electrolytes for your horse’s workload. However, if your horse suffers from a medical condition which could be antagonized by inappropriate electrolyte provisions it would be sensible to contact the manufacturer or a professional equine nutritionist to make sure the diet is supporting your horse correctly.

Why use an electrolyte to replace for these losses if electrolytes are present in the diet?

A complete electrolyte provides all the essential electrolytes in simple, readily absorbable forms which require very little digestion to release them ready for absorption. It also means the entire requirement for the horse can be administered in around 50g and eaten in ten minutes rather than the horse needing to eat 10kg of hay plus and a large serving of table salt, which could take 24 hours. This is particularly relevant for fit horses staying away at competitions who many not be eating as well as they would at home.

The key motivator for providing rapidly absorbable electrolytes promptly after exercise is to promote the best possible recovery from exercise. Here our focus is on rehydration, maximising muscle recovery and nerve function, to avoid associated illnesses like tying up and colic.

Why not just use table salt?

Table salt given on a daily basis will provide sodium and chloride to the horse, which are arguably the most important electrolytes to replace. Adding these two electrolytes to the diet is suitable for horses which may sweat moderately twice a week on the basis that there is ample time for the horse to eat and digest enough food between sessions to replace other lost electrolytes. However, if the horse is sweating more frequently than this, or have a predisposition to any other health conditions, such as tying up, a complete electrolyte would be more supportive.

Please remember, if you do not feed label directed volumes of a complete feed or pelleted balancer, you will need to balance the diet for sodium in addition for accounting for sweat losses regardless of work load.

Adding electrolytes to my horses feed puts him off his food…

This is a not a common dilemma, often affecting the horses who need electrolytes the most. Help is at hand as the Science Supplement Complete Electrolytes are encapsulated which disguises the taste of these salts and avoids any gastric irritation, as the oil encapsulation is not broken down until the small intestine.

For horses which flatly refuse to eat their meal with anything added to it we recommend using an electrolyte syringe. As these syringes are not normally given around feeding time we strongly recommend allowing the horse to graze or eat hay for 30 minutes before administering the syringe, never give an electrolyte syringe on an empty stomach.

What’s your top tip for feeding electrolytes?

Commonly, horse owners only think of feeding electrolytes through the summer, or around the time of a competition. For horses which sweat regularly, a complete electrolyte should be used on a daily basis to compensate for losses and promote a healthy recovery from exercise, maximising the horse’s ability to response positively to training. If your horse has sweated excessively at a competition or training session, increased provisions can be given for three days before returning to your normal daily serving.

For more information on our equine supplement range, click here or contact us.

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