• Briony Witherow BSc MSc RNutr. PGCERT FHEA

How to keep a horse hydrated

Briony Witherow, explains how to tell if our horses are well hydrated and why it is important


Hydration is often a forgotten part of our management but can have far reaching impacts when it comes to health and performance. Just like knowing your horse’s 'temperature, pulse, respiration' (TPR), knowing what is normal in terms of water intake, and other measures of hydration status is key.


Why is hydration important?

With water representing around 60-75% of a horse’s bodyweight, water is arguably the most important component of a horse’s diet. Insufficient replenishment of water can quickly cause dehydration, with a loss of just 2% having a detrimental effect on performance¹.


Water is lost through various mechanisms, one of which is through sweat. Sweat consists of water, a protein called latherin (which helps to spread the sweat) and electrolyte minerals. Under mild ambient conditions you could expect a 500kg horse to lose 5-7 litres of sweat per hour of steady trotting and cantering² ³. This can rise up to 10-12 litres per hour, under conditions of high heat and humidity ² ⁴. In addition to large amounts of water lost in sweat, electrolyte loss is estimated at ~10g per litre of sweat ⁵. This is important to note when it comes to staying hydrated, as electrolyte balance is integral to thirst response, making not only water but electrolyte provision key considerations for any hydration strategy⁶.


dehydrated horse, the horse hub
Latherin

While dehydration is well established as a factor in poor performance, it is also implicated as a key risk for several health concerns. Studies have identified dehydration as a key risk factor for colic ⁷⁻¹³; gastric ulcers14, urinary tract infections and disorders such as urinary calculi ¹⁵ ¹⁶ .


What can we do to keep track of hydration in our horses?

Monitoring real-time hydration in our horses is somewhat challenging and many indirect tests of dehydration like skin-pinch tests can be unreliable and perhaps more reactive than proactive. The following points detail a number of measures that we can look out for on a daily basis to keep tabs on hydration status:


Volume of water consumed

Water requirement varies between individuals and, is dependent on a number of external factors such as age; exercise intensity; moisture content of the diet; heat and ambient temperature; degree of sweating¹⁷.


What's normal? As a baseline a horse requires approximately 5 litres of water per 100kg bodyweight (25 litres for a 500kg horse).


Tips to help; Use buckets instead of automatic waterers (unless a flow meter function is available) Monitor your horse’s water intake over a normal week and take an average. Include not only volume but typical timing/behaviour.

Continue to check water intake daily (using measure stick or bucket with measurements).

Dehydrated horse, the horse hub

The number and duration of drinking bouts¹⁸

Drinking patterns vary depending on management, water availability and age of the horse. The average time spent drinking per day is short, at only 5-6 minutes. Horses fed dry diets drink around the time of feeding (10 minutes before and 30 minutes after)¹⁹.


Monitor manure consistency

Number, colour and consistency of droppings will change depending on diet, management and other factors. Extremes of consistency may provide an indication of hydration status. Firm faecal balls, which break easily typically indicate good levels of hydration, whereas very hard or dry manure may indicate dehydration.


Skin pinch test

Pinch the skin near the shoulder between finger and thumb. When released, the skin should return to its original position and shape immediately, if it takes 2-4 seconds to return, your horse may be dehydrated.

As water intake is very individual to your horse, his management and environment, keeping track of what is normal for an individual and checking in periodically (particularly if management or feeding changes) is essential.


Provide clean fresh water at all times

Clean troughs/buckets and check for contaminants regularly


Ensure sodium requirements are met

Even horses at rest or in light work that are receiving the recommended amount of a bucket feed are likely to require added salt. Feeding 30g (a heaped tablespoon) of table salt per day will provide 12g of sodium, which is sufficient to meet the maintenance requirements of a 500kg horse.

For moderate to hard work, particularly when combined with hot and humid conditions, horses will require electrolytes to keep them hydrated and support recovery from training and competitions.


Ensure ample fibre

Fibre acts as a reservoir for water and electrolytes in the gastrointestinal tract ²⁰⁻²³. This can act as a fluid reservoir for the horse during physical activity and periods when water is inaccessible and as such can help to reduce time to fatigue ²⁴.

Know how much forage your horse actually eats on a daily basis, even if fed ad lib; weigh what you put in and take out over a few days and take an average. If it is low, find ways to boost fibre intake such as alternative fibre sources (chaffs, beets etc.).

For particularly picky feeders, offering a range of forage choices ‘buffet’ style can help to increase overall intake. You can also apply this same approach to the travelling horse – next time you go somewhere, weigh what you put in and, take out, and see how much they are eating on the move. Knowing if there is an issue is half the battle, for those that won’t eat while in motion, ensuring regular stops to allow forage and water consumption is key and may have big implications for your performance the other end.


Make use of high moisture feedstuffs

In terms of fibre sources, providing grass, haylage, soaked or steamed hay as opposed to dry hay can help to increase dietary moisture content.

In addition to this, including succulents like carrots (~85% moisture) or opting for soaked fibre additions such as Fibre-Beet, Alfa-Beet or Speedi-Beet in place of dry chaffs can help to further boost moisture intake.


Beware of ‘foreign’ water

It is a common problem for horses to reduce water intake when away due to disliking the taste of ‘foreign’ water. To combat this, on short journeys or whenever possible take water from home with you. For times when this is not feasible, get horses used to drinking flavoured water (adding a small amount of Ribena/apple juice for example) at home so that when they are competing away, you can add this to ‘foreign’ water to help to maintain water intake.


Be aware of high-risk times when water intake may reduce

For example, cold weather, travelling/competing away

  • Horses prefer lukewarm water²⁵, so consider adding hot water to icy buckets in cold weather.

  • Decide on strategies to boost fibre and water intake ahead of travelling/competing to address any training aspect and ensure the digestive system has adapted to utilising any new feeds.


References

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2. McCutcheon L.J., R.J. Geor, M.J. Hare, G.L. Ecker, and M.I. Lindinger. (1995) Sweating rate and sweat composition during exercise and recovery in ambient heat and humidity. Equine Veterinary Journal Suppl. 20:153-157.

3. Kingston J.K., R.J. Geor, and L.J. McCutcheon. 1997. Rate and composition of sweat fluid losses are unaltered by hypohydration during prolonged exercise in horses. Journal of Applied Physiology, 83:1133-1143.


4. Flaminio, M.J., and Rush, B.R. (1998) Fluid and electrolyte balance in endurance horses, Veterinary Clinics of North America: Equine Practice, 14 (1): 147-158


5. Marlin, D. and Nankervis, K. (2002) Thermoregulation. In: Equine Exercise Physiology. Oxford: Blackwell Science, pp. 133-150.


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