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The Most Important Nutrient for Your Horses: Water — Part 1

7 minute read

Is Your Horse Getting Enough Water?

This is Part 1 of a two-part series about horse water requirements. Part 2 will focus on horse water-quality management.

As nutritionists, we spend a lot of time talking about protein, energy, fat, fiber and so on — but in reality, water is the number one priority. It’s second only to air in importance as a nutrient critical to life. It’s involved in everything from pumping of the heart and food digestion to lubricating joints and filtering waste through the kidneys. While we can’t control the amount of available air, we can control the amount of water we provide our animals.

Lack of water puts a horse’s vital systems at risk. A horse can live about a month without food —  but within 48 hours without water, they’ll likely start developing issues like colic, impaction, lethargy or other life-threatening problems such as kidney failure. Dehydration also affects milk production in lactating mares. If you notice your horse acting lazy or being a little more stubborn than usual, it could be a sign of dehydration.

This two-part series focuses on horses and the importance of providing adequate, clean water. In this first part, I’ve included some tips to ensure your horse is getting enough water. In Part 2, I’ll talk more about how you can better manage water quality your horses receive to help them stay active and healthy.

How Much Water Does a Horse Need Each Day?

It’s a great question, but the answer isn’t black and white. Water intake for a horse varies due to many factors. When it comes to water needs for a horse, size matters — the bigger the horse, the more water it’s going to require. Water requirements for a work horse or a Belgian, for example, will be greater than those for a quarter horse or pony.

A horse needs about three to seven liters of water per 100 kilograms of body weight, or about four to nine gallons per day for an 1,100-pound horse. Keep in mind this amount is usually met by drinking only 5 to 10 minutes per day. When a horse wants to drink, it’s imperative that you have a readily available supply that’s clean and pleasant to drink. Your horses won’t spend much time drinking water on a daily basis.

Lifecycle Stages

Stages in a horse’s lifecycle are important too. With colts, for instance, their initial water requirements are met by the mare’s milk. But by about a month of age, they’ll start eating a pretty significant amount of feed and/or be nibbling at dry forages — their water intake may be as high as a gallon a day by this time. When they shift to more dry feed such as hay and grain (and less milk), their water intake increases. Conversely, an older, more mature horse that’s exercised less may typically have a lower water intake. A horse’s daily water needs are a reflection of their workload.

Symptoms of Dehydration

Outside of ensuring your horse has available water 24/7, there are some visible signs a horse has become dehydrated. Dehydrated horses may have sunken eyes, and you’ll usually see thick saliva or a thickened mucous discharge. Another easy way to tell if a horse is dehydrated is through a simple skinfold test: Just grab a pinch of skin on the neck or anywhere there’s smooth skin, and the skinfold should snap back almost instantly. If it remains as a ridge for 2 to 5 seconds, the horse is mildly dehydrated. If it remains as a ridge or a tent for 10 to 15 seconds, the horse is extremely dehydrated, and you should call your veterinarian to get IV fluids in as soon as possible.

What Makes Water Requirements Increase or Decrease?

Water requirements change with the horse’s level of work. A pleasure horse that’s ridden often and aggressively will have higher water requirements than one that’s only ridden occasionally. Performance and work horses will require one and a half to two times more water due to losses in sweat, respiration, higher feed intake and increased urination.

Things like working, racing, endurance rides, hunts or hill-topping increase work sweat and respiratory water loss, thus, increasing their water demand. Horses exercised in hot humid conditions can lose gallons of sweat and critical electrolytes, depending on the length of the exercise.

Horses may also lose a significant amount of hydration when being hauled long distances. Even if the horse has only been in the trailer for an hour or so, it can suffer hydration losses.

Water requirements change with the season too. Water requirement increases with increased ambient temperature and humidity. Just like with humans, when it gets hot, we’re instructed to stay hydrated. The same is true for our horses. When temperatures drop, water intake also tends to decline in horses due to less evaporative loss and lower exercise. However, be aware that water requirements may go up in winter as the horse is consuming more dry feed and hay, and less lush grass.

How Does Feeding Impact Water Needs?

Grass intake can have a direct effect on your horse’s water intake. If the horse is primarily eating a lot of lush grass, it may not need to consume much water if its exercise level is relatively low. If you water using a five-gallon bucket and it’s still full, don’t assume your horse didn’t need that amount of water — it simply got the water from the grass versus drinking.

Grass in the spring or fall has about 80% or more moisture. That means water intake is going to be low as the temperature is lower. In summer it may seem like your horse is eating a lot of grass, but the grass’s dry matter this time of year is around 60% or 70% — and that decreased water content compounds when you add in heat and humidity. Even though it looks like your horse may be eating a lot, it makes sense that it’s going to consume more water throughout the summer.

Another important consideration is the impact of changing your horse’s feed. For example, if you got a new load of hay and it contains more alfalfa, your horse will likely drink more water. Simply by changing the fiber content of the diet from an alfalfa hay to a grass hay can also change your horse’s water intake because of the amount of water that it actually holds in the feed as it moves through the gastrointestinal tract. Alfalfa will create wetter feces, so water intake goes up.

The key here is to monitor your horses and understand the different factors that change how much water they need each day. Don’t let yourself get into the habit of simply filling a bucket once or twice a day or leave an automatic waterer unattended at length.

Supplement Zinc to Prevent Leaky Gut and Dehydration

Gut integrity is an important part of preventing dehydration in horses. If a horse is dehydrated, then it’s likely that they are suffering from a condition called leaky gut, leading to additional body moisture loss. Including zinc from performance trace minerals in your equine nutrition program strengthens the bond between the epithelial cells in the gastrointestinal tract, helping to maintain the tight junctions and decrease the occurrence of leaky gut.

Ensure your horses have plenty of fresh, clean water 24/7 to keep them properly hydrated and healthy. To learn more about your horse’s water needs and feeding performance trace minerals in your equine nutrition program, contact your Zinpro representative today. For more information about water quality, visit us online.