Dehydration In Horses


Water is essential for life and the composition of your horse’s diet can have a significant impact on water intake. There can be around 50 litres of water in the digestive system but this is significantly influenced by diet. Horses at grass for longer periods usually consume far higher levels of water than stabled horses as grass is around 80% water, hay is only about 15% water and haylage typically between 30 and 50%.

Meal feeding can also affect fluid balance in the body with research showing considerable shifts in water out of the digestive system when meals are fed. Feeding a few large meals each day can cause sufficient dehydration in the colon to result in impaction which could initiate other forms of very serious colic such as large colon displacement.

horse being exercised on hot day

Causes of Dehydration in Horses

There are many factors that contribute to dehydration in horses including:

  • Excessive sweating, caused by strenuous exercise or increased temperatures
  • Failure to drink – animals that are under stress especially those affected by disease may fail to drink. This is even more important in foals who become dehydrated very quickly.
  • Dietary factors

Signs of Dehydration in Horses

Dehydration in horses not only affects their performance, but it can also have serious implications for their health and potentially be life-threatening. Symptoms of dehydration can be confused with other things but the typical signs to look out for are:

  • Poor performance especially early onset of fatigue when working
  • Lethargy and depression
  • Darker-coloured urine

How to Hydrate a Dehydrated Horse

In a serious case of dehydration veterinary attention is required to administer fluid therapy to rehydrate the horse. To reduce the risk of dehydration in horses there are various things you can do:

  • Encourage your horse to drink – Horses often prefer the water from the field tank rather than fresh from the tap and so if they don’t normally drink much out of the bucket while they are in the stable or away from home, try filling it with water from the tank in your field. Another way to entice a fussy drinker to their water would be to add some flavour with a little cordial or food flavouring.
  • Use a soaked feed – the horse doesn’t actually have to drink from a water bucket and so may be more inclined to consume wet feeds. Dengie have a range of pelleted fibres such as Alfa-Beet or Grass Pellets which can easily be soaked to a sloppy mash as a more tempting way to aid hydration.
  • Consider using haylage rather than hay – a true haylage will have at least 30% water and so will provide more water than hay. As the horse consumes so much more forage than bucket feed this can have a significant impact on total water intake
  • Turn out if possible – grass is 80% water so some time out grazing will increase water intake. Obviously this isn’t feasible if the horse is prone to laminitis as the grazing presents a greater risk to their health.

horse drinking water in field

Top Tip for Summer

It is important to have fresh clean water available to your horse at all times of year but you may find the sunshine and warmer weather means you’re having to wash out and change the water in your field more frequently than you would do normally.

Feeding Electrolytes To Horses

Rising temperatures and harder work can cause your horse or pony to sweat more resulting in the loss of electrolytes. Electrolytes are minerals that are found in fluids in the body and their concentration in and around cells affects neuro-muscular function. Electrolyte losses and dehydration are linked to fatigue and ultimately compromise performance. Excessive losses can have serious repercussions for health too. Horses that appear to get tired towards the end of their work may well be doing so as a result of electrolyte losses, particularly if they are working in hot conditions. Click here to read more about feeding electrolytes to horses.

How to Cool down a Horse in Hot Weather

Walking can help to cool your horses, by increasing the movement of hot air from the body and replacing it with cooler air. Ensuring the horse is in the shade and out of direct sunlight will also increase convection cooling. It is also important to physically cool the horse down after exercise. Cold water applied all over the body has been proven to be one of the most effective ways to keep horses cool. It is important to ensure the water temperature is cooler than the horse so that heat can be lost through both evaporation and conduction (transfer of heat from the body to the air).

horse wash down

The cool down period helps to bring the horse’s temperature and respiration rate down but it has another important function. The lymphatic system is crucial to the horse’s health, performance, and recovery. It consists of an extensive network of vessels and nodes that help to maintain fluid balance and cellular health. After exercise, the lymphatic system clears the waste generated by cells that have been working hard to supply the fuel that powers performance. A cool down for around 20 minutes helps the lymphatic system to work efficiently.

Top tips for helping to prevent dehydration:

  • Ensure fresh clean water is available at all times.
  • If your horse doesn’t like drinking fresh tap water while in, try filling a bucket from the field tank.
  • Adding cordial or food flavouring to water can help tempt fussy drinkers.
  • Using soaked feeds can help aid hydration without the horse having to drink from a bucket.
  • Adding salt or electrolyte supplements can help replace what is lost through sweating.
  • Ensure your horse is sufficiently warmed up and cooled down before and after exercise.
  • Cold hosing is the most effective way to cool the horse down.

For personalised feeding advice call the Dengie Feedline on 01621 841188 or click here to complete the Feed Advice Form.