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Why winter hydration is crucial

Dehydration in the winter months may not be a foremost concern for horse owners, but everyone should be aware of the potential dangers. Vet Karen Coumbe explains the importance of staying hydrated, whatever the weather.

Given the heat and sweat of the summer months, many owners may think that dehydration is a fair-weather concern. However, it's important to be aware of the risks of fluid loss year-round - frozen drinking water and dropping temperatures in the winter months can mean that some horses actually drink less, increasing the possibility of dehydration.

The cold facts

Horses can survive for weeks without food, but only three or four days without water - it is vitally important for their health and wellbeing, and makes up around 60% of their body weight.

Whatever the weather or the season, average Thoroughbred-sized horses require at least 20-30 litres of water a day to drink (so at least two big buckets, assuming a bucket equals 10 litres) - more if they are doing lots of exercise. Mild dehydration is akin to a human hangover, and vets estimate that a 1 per cent loss of hydration leads to 4 per cent reduction in performance. But there are more serious consequences to consider, too.

First, dehydration can increase the risk of colic. Horses store large amounts of water in their gastrointestinal tract and if the contents become too dry, this can lead to impaction colic. This tends to be exacerbated in winter, when horses are stabled more, exercised less and eat an increased amount of fibre, such as hay.

Second, a dehydrated horse can be more prone to respiratory infections or the worsening of conditions such as recurrent airway obstruction. This is because the mucous lining the airways thickens and clears more slowly from the lungs.

Signs of dehydration

You need to know what is 'normal' for your horse - how often he passes urine and droppings, the colour of his mucous membranes and his energy levels. Signs that he may be unwell and/or running low on fluid are:

  • Dark urine or not passing urine regularly
  • He looks dull, listless and depressed
  • Dark red gums and inside the eyelids, rather than a healthy salmon pink
  • Decreased performance levels

The 'skin pinch test' - where the skin is pinched and the time taken to return to normal is counted in seconds - is no longer considered a reliable indicator of hydration levels. The gold standard test is a blood sample to confirm dehydration - consult your vet if you're in any way concerned about dehydration.

Six ways to prevent dehydration

As the saying goes, you can lead a horse to water but you can't make it drink. To help prevent your equine friend suffering from dehydration, follow these six steps:

  1. Always ensure there is fresh water available. Horses don't like chilled water, especially in the winter, so add a little hot water if it's too cold.
  2. Always consider how much water your horse is getting in his feed. If his rations are dry, make extra efforts to provide plenty of water.
  3. Break or melt ice on outdoor troughs every day, and take time to check that automatic drinking systems are not frozen. In sub-zero conditions, floating an apple in your horse's water buckets can help to slow down the freezing process, due to the bobbing motion of the apples.
  4. The lush grass that horses graze on in the spring contains lots of moisture. In winter horses tend to be stabled more, and therefore eat less grass and more hay. To ensure your horse is getting the moisture he needs, soak the hay, or feed him haylage rather than dry hay, as it has a higher moisture content.
  5. If your horse is drinking less than normal, consider adding electrolytes or a teaspoon of salt to his feed, which will encourage him to drink. But do consult your vet if you need to do this regularly, as large amounts of salt can be harmful.
  6. If your horse has a thick coat, he may sweat more profusely, so clipping will be beneficial.