Farming Magazine - March, 2013


Working Horses: Factoring in Hydration

By Vicki Schmidt

If you're involved with livestock and conscientious about their care, you probably spend a considerable amount of time making sure your animals are properly watered and that their water is fresh and clean. Add to this the concept of hydration, especially that of the working horse, and you raise your knowledge to a higher level.

A horse becomes dehydrated when water intake is insufficient or there is an excessive loss of water from the body, usually in the form of sweat. There are a variety of factors that can affect these two issues, especially for the working horse. These include aspects of forage; weather and working conditions; access to fresh, clean water; and your horse's access to salts.

Forage and vegetation

Horses are foraging creatures and enjoy a grass-based diet, but given a choice they will also feed on leaves, berries, twigs and tree bark. In addition to helping to keep a horse's teeth in naturally good shape, a variety of forage provides for adequate roughage and also helps maintain trace minerals and vitamins.

How forage and vegetation relate to hydration in the horse is dependent on the moisture content of the forage. Working horses with a hay-based diet will need more water to help rehydrate and digest their food than horses on a fresh grass-based diet. Seasonal changes in the availability and quality of graze and hay will also affect your horse's consumption of fresh water.

Weather and working conditions

Along with forage, the daily weather and working conditions will also have an impact on your horse's need for water. Horses receive the signal that they are thirsty much differently than humans. This is due to a combination of factors, mostly related to how horses process salts and electrolytes, as well as the large amounts of water retained by their internal organs. Realize that your horse can be clearly dehydrated, yet still not be thirsty due to a horse's natural lack of an early warning "thirst signal."

Attention to the weather, how you are working your horse and its degree of sweating is essential to secure its hydration factors. A working draft may appear not to sweat as much on one day due to the dryness of the air, sunshine, rainy mist, a cool breeze or other conditions. Do not be deceived by a horse that appears to be working well and well hydrated at the moment. Monitor for hydration at all times and allow for adequate rehydration during rest or harsh weather conditions.

Access to fresh, clean water

Consider that your working draft can lose 2 to 3 gallons of water per hour from sweating alone. Ideally, this water needs to be replaced while performing the work. Providing your working horse with water between 45 to 65 degrees every hour while it's working is a good start to ensuring adequate hydration.

Given a leisurely day and free-choice water, nursing mares will drink every two hours, while the majority of other horses will choose to drink the bulk of their water early in the morning or later in the afternoon. The average draft on a leisurely day can easily consume 35 gallons of water, while working drafts nearly double that, or more, in order to stay hydrated and healthy.

Access to salts

Horses lose salts and excessive moisture primarily by sweating. Realize that most electrolyte and water loss occurs early during work or exercise and that salts and electrolytes are not immediately processed for use upon consumption. It takes hours, often days, for a working draft to replace certain salts and minerals that are expelled with its sweat. Salts and minerals are vital to proper nerve and muscle function. A horse with low electrolyte levels shows fatigue and nervousness, and the horse's muscles may stiffen and tremble.

Potassium and other minerals found in electrolyte supplements are often the answer to help a working horse retain the proper salt and nutrient balance that it requires for efficient work. Many of these are easily top-fed with grain rations or provided with a secondary water bucket. Consult with your veterinarian or an equine nutritionist if you have questions regarding a particular horse's needs.

Since horses do not have an early warning signal of thirst for pending dehydration, it is crucial that you understand and monitor your draft's hydration factors, especially under working conditions.

How do you determine if your horse is adequately hydrated?

  • The pinch test - Using the pinch test is a quick and easy indicator of your horse's hydration factors, as skin inelasticity is an indication of dehydration. Pinch a bit of skin at the point of your horse's shoulder or along its neck and release it. If it flattens back into place immediately (less than one second), your horse is adequately hydrated. If it takes more than two to three seconds, your horse is experiencing dehydration and it's critical to get more water and possibly salts into it.
  • Capillary refill time - Press solidly, but gently, on your horse's gum above the front teeth. The skin changes from pink to white as you press. Release the pressure and count how many seconds it takes for the pink color to return. Less than a second or two is ideal, while three seconds or more indicates dehydration.
  • Stress to internal organs - Ask your vet to show you how to check your horse's heart rate along its ankle. Normal heart rate is between 36 and 42 beats per minutes (BPM). If your horse's heart rate is 60 BPM or more, this is often an indication of severe dehydration. In addition, normal respiration will be negatively impacted by dehydration. A normal horse respires 12 breaths per minute. A dehydrated horse will have higher-than-normal respiration, and the breaths will also be more shallow.

As a conscientious owner, support factors that encourage adequate hydration for your horse. Even mild dehydration leads to a variety of negative health and wellness issues, including colic, which is a leading cause of premature death in domesticated horses. With any horse, and especially with working drafts, the goal should always be to prevent your horse from becoming thirsty, as thirst in a horse is a sign they are already well on their way toward significant dehydration.

Vicki Schmidt owns and operates Troika Drafts, a 100-acre working farm in western Maine. Visit them online at