The Importance of Hydration

Summer has arrived! It’s a season many of us look forward to, as longer, warmer days set the scene for fun in the sun with our four-legged friends. However, the summer months do present their own set of challenges when caring for our horses; maintaining adequate hydration and minimising electrolyte loss are two of the most important considerations when preparing for the sometimes harsh conditions Australian summers can present.

Horses do not naturally have a strong thirst drive and will often spend only a few minutes each day drinking water. As such, ensuring water sources are clean, fresh, easily accessible and appealing for the horse is the first step we can take to promote adequate fluid intake, particularly during the summer months. While some horses are spelled during summer, meaning their requirement for electrolyte supplementation will differ from those that are exercised, promoting adequate hydration is the first principle of summer horse care, regardless of the animal’s workload.

Did you know?

Horses can consume up to 50 litres of water per day and are likely to drink twice as much water if the water is cooler than 30 degrees.

As such, position water troughs and tubs in the shade where possible, and consider providing multiple water sources for horses kept in herd environments. Horses grazing on lush pastures will naturally take in more water through the grass they consume than those relying on dry pasture and/or hay and other feeds; remember to consider your horse’s diet when monitoring your horse’s water intake.

Did you also know?

Water makes up approximately 65-75% of a horse’s body weight; if a horse becomes dehydrated due to insufficient water intake and/or fluid loss, the impact can range from appetite loss, lethargy and poor performance in mild cases, to major impacts on vital organs such as kidney failure, and death in severe cases.

What are electrolytes & how can they help?

An electrolyte is a mineral that conducts electricity when dissolved in water. As with humans, many of the automatic processes in the horse’s body rely on a small electric current to function. Electrolytes provide this, interacting with each other and the cells in the tissues, nerves, and muscles. The right balance of different electrolytes is vital for healthy, normal body function.

Electrolyte levels can change in relation to factors such as water levels in the body; when the level of an electrolyte in the blood becomes too high or too low an imbalance can occur. Important electrolytes are lost in sweat when the horse exercises, including sodium and potassium, however, in hot summer conditions a horse can sweat while resting in the paddock or stable, creating the same effect, particularly if they have limited access to shade or are rugged. Horse sweat is more concentrated in electrolytes than blood – the opposite of humans – hence the potential for extreme electrolyte loss when horses exercise and sweat.

The minerals collectively referred to as electrolytes are sodium, chloride, potassium, calcium, and magnesium. If your horse is not ingesting the correct amount or balance of these minerals through its diet to suit the animal’s environment and workload, electrolyte supplementation will be necessary.

So, what roles do sodium, chloride, potassium, calcium, and magnesium play?

Sodium plays an important part in central nervous system function, including nerve impulse transmission and moving substances such as glucose across cell membranes. It’s also an important electrolyte involved in maintaining body fluids’ acid-base balance and osmotic pressure regulation. In simple terms, it helps tissues and organs retain water.

Chloride plays a critically important role in the horse’s digestive system as it produces stomach acid. Like sodium, chloride also works to keep the body’s fluids at a neutral pH, enabling the body to function normally. Chloride also controls the excitability of muscle and nervous tissue, aids sweat production and regulates fluid balance in cells.

Feeding a 500kg horse 30ml or 2 tablespoons of salt each day, all year round, regardless of the climate or whether they are in work, will ensure they are receiving a maintenance level of sodium and chloride (NaCl). While hay and grass are low in sodium, many processed feeds include added salt, therefore it’s helpful to check the nutritional breakdown of products your horse is fed when considering how much salt to add to its diet.

Potassium is important for normal nerve and muscle function and relaxation. Forage is generally high in potassium and healthy horses normally excrete excess potassium in their urine, however, there are risks associated with both excess and insufficient potassium intake. A horse’s sweat contains a high percentage of potassium, and if depleted of this electrolyte, horses can experience muscle weakness and fatigue, along with decreased appetite and water intake. If the horse’s kidneys fail to filter out excess potassium in the horse’s diet, this can result in a serious condition known as hyperkelemia, which involves over-contraction of muscles, cramping and an irregular heartbeat. Excess potassium can also inhibit the body’s absorption of calcium and magnesium.

While sodium, chloride and potassium are considered the three most important electrolytes, calcium and magnesium also play an important role in maintaining the normal function of muscles and nerves.

When should an electrolyte supplement be fed?

A healthy horse with a balanced diet including forage and adequate salt, that is either in light or no work and not exposed to excessively hot or humid conditions, is unlikely to require a daily electrolyte supplement. A horse’s body holds reserves of electrolytes and will draw on these if required. However, any situation that causes the horse to sweat, including hot weather, exercise, travel or other forms of physical stress, can cause these reserves to be depleted and trigger the need for additional supplementation. An exercising horse can lose up to 10-15 litres of sweat per hour, which can not only lead to dehydration but also the loss of key electrolytes.

Choosing the right electrolyte supplement for your horse

A horse that is sweating regularly due to its environment or workload will require electrolyte supplementation beyond the daily provision of salt. Electrolyte powders, which can easily be mixed into the horse’s feed, are suitable for these situations. Virbac’s Humidimix is designed to provide a balanced daily intake of electrolytes, and is formulated for horses that lose large volumes of sweat. It does not contain fillers such as sugar, and encourages drinking to prevent dehydration.

With higher levels of chloride, potassium and magnesium than many other electrolyte supplements available, Humidimix has been formulated to aid in the treatment of “alkalosis”, a condition caused by a greater loss of chloride in sweat compared to sodium. Disproportionate loss of chloride leads to an increase in blood bicarbonate levels, resulting in blood becoming alkaline.

Liquid electrolyte supplements are a great way to rapidly restore depleted electrolytes while stimulating hydration. Products such as Virbac’s Recharge are highly palatable options that can be administered after exercise or travel, and can either be diluted in water or administered by oral syringe; as such, liquid electrolyte supplements can be a handy choice for horses who reject the addition of powdered supplements to their daily feeds.

Introducing and offering Recharge diluted in water to the horse in their home environment, in the days and weeks prior to travelling or a period of intense exercise, can be a useful way to accustom and encourage the horse to drinking a palatable “sports drink” liquid, while also building up the horse’s store of electrolytes before these are depleted. A horse that accepts water when it is offered before, during or after travel or exercise is less likely to suffer from dehydration and electrolyte loss than one that shows little interest in drinking at these times.

Electrolyte supplements in paste form, such as Virbac’s Bectyl Paste, are convenient to have on hand when travelling or after strenuous exercise. Administering electrolytes via a paste is a fast and easy way to quickly replenish lost electrolytes. In addition to key electrolytes, Bectyl contains B-group vitamins, vitamin E and citrate, scientifically balanced to aid the horse’s recovery from exercise and rehydration process.

Maintaining the right balance of electrolytes is the key principle regardless of which format electrolytes are administered in. Adequate hydration, electrolyte balance and replenishment are the first principles of maintaining optimum health during the summer months. Knowing when your horse requires supplementation beyond daily access to salt will ensure that when your horse sweats this summer, it won’t be to their detriment.