Hydration in Horses

Written by Briony Witherow MSc RNutr. FHEA

Hydration is often overlooked in horse management, but it underpins everything from performance to gut health. Water makes up 60–75% of a horse’s bodyweight, and even a small shortfall has consequences. Just a 2% loss of bodyweight through dehydration can impair performance, while more severe deficits increase the risk of colic, gastric ulcers, urinary problems, and fatigue.

How Horses Lose Water

Water is lost daily through urine, faeces, and respiration, but sweat is the major additional route during exercise and hot weather. A 500 kg horse can lose 5–7 litres of sweat per hour of steady trotting and cantering in mild conditions, rising to 10–12 litres in heat and humidity. Alongside water, sweat carries electrolyte minerals which are critical for thirst response and muscle function. If electrolytes are not replaced, simply offering water may not be enough.

Monitoring Hydration – Know What’s Normal

Checking hydration in horses isn’t always straightforward, and common tests like the skin pinch are more reactive than proactive. The best approach is to know what’s normal for your individual horse and track it over time.

Key measures include:

• Water intake – As a baseline, horses need around 5 litres per 100 kg bodyweight (25 litres for a 500 kg horse), but this varies with diet, workload, and climate. Use buckets rather than automatic drinkers to measure intake.
• Drinking patterns – Most horses only drink for 5–6 minutes per day, usually around feeding. Watch for changes in frequency or enthusiasm.
• Manure – Firm, moist droppings that break apart easily suggest good hydration; very dry or hard droppings may be a warning sign.
• Skin pinch – Slow return (2–4 seconds) can indicate dehydration, but compare to your horse’s normal baseline.

Practical Ways to Promote Hydration

1. Provide clean, fresh water at all times
Clean buckets and troughs regularly. Horses can be fussy and may refuse water with algae, debris, or contamination.

2. Meet sodium and electrolyte requirements
For most horses at rest or light work, adding table salt to the ration (around 30 g per day for a 500 kg horse) is enough to meet baseline sodium needs. Salt licks can also be offered, but monitor intake for consistency.

For those in moderate to hard work, or exercising in hot or humid conditions, an electrolyte supplement is essential. Products such as Everyday Electrolytes provide a balance of sodium, chloride, and potassium for daily use. For harder training and competition schedules where rapid recovery is needed, Restore-Lyte Powder or Restore-Lyte Liquid may be a better choice as it combines electrolytes with ingredients to support muscle glycogen replenishment. 

3. Fibre fuels hydration
Fibre in the diet acts as a reservoir for water and electrolytes in the gut, creating a buffer against dehydration. Adequate forage intake supports hydration as well as gut health. For horses reluctant to eat forage when travelling, soaked beet pulp or fibre mashes can be an effective way to maintain intake.

4. Use high-moisture feeds
Haylage or soaked/steamed hay provide extra water compared to dry hay. Succulents such as carrots (85% water) or soaked beet pulp are also useful ways to boost water intake, particularly for stabled horses.

5. Manage “foreign” water issues
Some horses refuse unfamiliar water when travelling. Where possible, take water from home. Alternatively, train horses to accept flavoured water (e.g. apple juice, or a splash of their usual fibre mash) so the same flavour can disguise taste differences away from home.

6. Prepare for high-risk times
Water intake often dips in cold weather. Horses prefer lukewarm water, so adding hot water to icy buckets can encourage drinking. Before competition or travel, trial fibre mashes and electrolyte strategies at home so your horse is accustomed to them.

Take-Home Messages

• Hydration is central to performance, gut health, and overall wellbeing.
• Salt and electrolytes are essential
• Fibre is a key hydration reservoir, not just a calorie source.
• Anticipate challenges like travel, competition, and cold weather, and plan hydration strategies in advance.

By combining good management with targeted use of salt and electrolyte products, you can help ensure your horse stays hydrated, healthy, and performing at their best year-round.