two horses drinking water

How Long Can A Horse Go Without Water?

Dehydration is the result of excessive loss of water in your horse’s body. It is one of the most common challenges a horse will face in its lifetime, so it is essential to be able to recognize and treat the symptoms of dehydration quickly – your horse’s life may depend on it!

Horse Dehydration Prevention

Did you know that your horse’s bones are made up of about 30% water, his muscles about 75%, and his brain a whopping 85%? Water makes up about 60% of your horse! Water is an essential nutrient that is needed for almost every bodily function. It’s little wonder that dehydration and loss of vital electrolytes (salts) will not only negatively affect a horse’s performance, but it can lead to systemic (internal) and neuromuscular imbalances that can lead to severe and even life-threatening health issues for your horse, if left unchecked.

Electrolytes are responsible for the transfer of water through the cell membranes, which keeps the horse’s system balanced and working correctly. The loss of too much water and essential electrolytes will cause the horse’s body to become stressed. This can quickly lead to a variety of physiological problems, including fatigue, kidney impairment or failure, muscle spasms and reduced muscle function, inadequate respiratory responses, gastrointestinal stasis, and heart arrhythmias to name just a few.

Horses sweat in much the same manner as humans do to rid their bodies of excess heat. But dehydration from excessive activity, coupled with sweating, can cause the loss of essential fluid reserves and electrolytes needed, not only for continued activity but for the continuation of life. For example, just to fulfill their basic physiological needs, most adult horses that weigh around 1,000 pounds (which is NOT a big horse!) require at least 10 to 12 gallons of water each day! Under moderate conditions, a trotting horse will lose slightly over 3 gallons of sweat per hour, so it’s easy to see how quickly your horse may become dehydrated to the point of irreparable harm. And equine sweat contains more salts than body fluid (hypertonic), which means that a sweating horse loses more electrolytes than water.

Common Causes of Horse Dehydration

  • horse exercising and getting dehydratedVigorous exercise, long rides, or racing, especially on hot, humid days
  • Increased respiration rate
  • Endurance/trail riding
  • Athletic events
  • Long bouts of diarrhea
  • Fever or abnormally high body temperature (hyperthermia)
  • Anaphylactic shock (triggered by an allergic reaction)
  • Severe burns
  • Colitis-X (a disease which causes watery diarrhea and hypovolemic shock)

Dehydration can also be a problem during cold, winter weather, as well. In cold weather, a horse’s thirst may be significantly reduced. Instead of losing excessive amounts of water through sweating, as they do in hot weather, horses lose water even on the coldest days through such functions such as the saliva they use to soften their food, through urine and feces, and also the moisture in their breath. With a diminished thirst trigger, dehydration is a danger – even in the dead of winter. And remember – snow is NOT an acceptable substitute for plenty of good, clean water for your horses. Just as humans often enjoy hot beverages during winter months, warming the drinking water for horses (to a temperature of around 90 degrees), during the winter, will result in the horse consuming more water.

How Can I Tell If My Horse Is Hydrated?

Remember – It’s essential to act quickly to intervene in cases of dehydration, and the way to do that is to be able to recognize the symptoms before severe damage is done.  The most reliable way to diagnose dehydration is to take a blood sample to determine the level of proteins in the plasma, along with the proportion of red blood cells in the blood compared with the plasma. Your veterinarian may also order a urine test. However, there are other means by which you may be able to detect the effects of dehydration in your horse. Although these not as specific as blood or urine tests, they are generally reliable as diagnostic indicators that your horse may be in a state of dehydration and imminent need of intervention.

The Pinch Test

Probably the most straightforward test to check for signs of dehydration in your horse, is the pinch test.  As with humans, a horse’s skin loses its elasticity when it’s in a state of dehydration. S0 pinch up a fold of skin anywhere along the horse’s back, or, near the base of the horse’s neck, or on his lower chest. Hold it for 2 seconds, then release it. If the skin is NOT dehydrated, it should immediately spring back to normal. If the horse is dehydrated, the skin will stay up in a ridge, and the longer the ridge remains is an indicator of the severity of the dehydration. If the skin remains in a ridge for 10 to 15 seconds, seek veterinary assistance immediately, as your horse may be dangerously dehydrated.

Respiration Rate

barn fire orevention hayThis is an excellent quick check for your horse’s health. A typical breathing rate for an average horse is between 8 and 12 breaths per minute. If a horse is dehydrated, he will take more frequent, shallow breaths, as his body tries to move its vital resources from one system to another to maintain a sense of normalcy. 

Heart Rate

A horse’s resting heart averages about 36 – 42 beats per minute. For best results, try to count his pulse for 60 seconds. A resting heart rate higher than 60 beats per minute may be an indication of dehydration. (Avoid 10 seconds of pulse multiplied by 6, if possible – the results may be inaccurate.)

Check Eyes and Gums

The mucous membranes should appear moist and shiny. Excessively red gums and/or dry-appearing eyes may indicate that your horse is moving fluid from those regions to more core body functions to compensate for dehydration. Another easy test is to press gently on the gum near your horse’s upper teeth, with your fingertips, and release. As you press, the skin will turn white, or pink. When you release, the color should return quickly. This will determine how long it takes the capillaries to refill. More prolonged refill means a higher chance of dehydration. Anything longer than 2 seconds, for the color to return to his gums, may indicate dehydration.


A horse that produces dark urine or has not passed urine for an extended time may be dehydrated.

Other Symptoms of Horse Dehydration

  • Lethargy/sluggish activity/fatigue/depression
  • Loss of glossy coat/dry skin
  • Signs of pain/Muscle spasms
  • Thick and sticky saliva
  • Decreased feed intake due to lack of saliva
  • Constipation/impaction colic
  • Cardiac arrhythmias

What Can I Do If My Horse Is Dehydrated?

horses get dehydratedFirst and foremost, the administration of fluids and electrolyte solutions is vital in the treatment of dehydration for horses. Contact your veterinarian, as the dosages are essential and require medical expertise. One easy remedy while you are waiting for the vet to give advice or to arrive, is to give your horse a nice bath – this depends of course on the time of year etc….you don’t want to bath your horse in the middle of winter…depending on where you live!! It is possible that excess rehydration can lead to a condition called water intoxication. In this condition, excessive water intake can cause stress on the kidneys and dilute the electrolytes in the horse’s body, which hampers their ability to regulate body temperature. Research has shown, however, that healthy horses generally do not drink beyond their body’s normal capacity based on body weight or weather conditions. Be aware that there are medical conditions and even diet imbalances (such as high levels of fiber/hay, salt, potassium, and protein in the diet) that may cause your horse to over-hydrate, in this case; you should seek the advice of your veterinarian as soon as possible.

For less severe dehydration, be aware that offering water alone does not always sufficiently rehydrate a dehydrated horse. The water may simply dilute the body fluids surrounding the tissues – effectively turning off the thirst mechanism. Some effective rehydration therapies that may stimulate drinking include the administration of electrolyte preparations in feed or water, which are commercially available in rations specifically formulated toward activity levels. Increased hydration can also be stimulated by adding extra water to your horse’s mash and letting it sit for 10 minutes to allow for expansion of the grain, as well as increasing your horse’s salt intake – keeping in mind that the recommended daily intake of salt for a 1,000 pound horse should be about two ounces.  

How To Prevent Horse Dehydration

Unlike many conditions over which horse owners have no control, dehydration is often totally and easily preventable. GIVEN THE OPPORTUNITY TO DRINK AND THE AVAILABILITY OF FRESH, CLEAN WATER, MOST HORSES WILL NOT SUFFER FROM DEHYDRATION!

Here are some simple steps that owners can easily practice to prevent horses from suffering the effects of dehydration, especially during stressful or strenuous events. 

  • horse hydration is importantMake sure that your horse has plenty of fresh, clean, palatable water to drink and access to salt at all times. If you’re feeling thirsty or dehydrated, the chances are that your horse is feeling the same.
  • Be sure to frequently check water troughs and buckets, scrubbing and refilling as necessary.  
  • Pay attention to each horse’s unique level of activity and weather conditions.
  • Make sure that electrolytes and fluids are balanced and at appropriate levels for the activity level of the horse and the weather.
  • Never ride or exercise a horse to the point of exhaustion. One way to practically guarantee dehydration and electrolyte imbalance in your horse is to force him/her to be active during hot, humid weather.
  • Do not restrict your horse’s access to water at competitions.
  • Check for signs of dehydration regularly.
  • Don’t wait until a horse looks dehydrated to administer electrolytes. If your horse doesn’t seem to like the taste of water when you travel, bring some from home. You can also add a masking flavor such as apple juice, mint, or a commercial product designed to help horses drink.
  • Consider the higher moisture content of well-soaked beet pulp for a horse that isn’t drinking well. It will provide the horse with water and fiber, reducing the risk of colic.  
  • On a hot day, cool your horse off thoroughly, as soon as possible after exercising. Try to keep your horse in the shade whenever and wherever possible, especially at competitions. And remember to administer electrolytes to help replace the salts in the body lost through sweat.
  • When traveling with your horses, consider stopping every two to three hours to offer your horse water. This will keep him hydrated and better able to tolerate traveling over long periods. Also, consider giving them some well-soaked beet pulp the day before and if possible the day of the journey.
  • Finally, if there is any doubt as to the severity of the situation, seek expert veterinarian care immediately!

Banixx For Horses

Learn more about Banixx and its many uses for horses, such as treating scratches.