How To Tell If Horse Is Dehydrated: Signs

A horse is dehydrated when it loses more body fluid than it takes in. This is a serious issue that needs quick attention. Checking horse hydration levels is vital for good horse health.

Why Water Matters So Much for Horses

Horses need a lot of water every day to stay healthy. Water helps many body jobs. It keeps blood flowing well. It helps move food through the gut. It also keeps the horse cool when it is hot or exercising.

A horse might drink 5 to 15 gallons of water daily when it is mild outside. If the horse works hard or the weather is hot, it might drink much more. Even a small loss of body water can make a horse sick fast. Losing just 5% of body water can cause problems. Losing 10% or more is an emergency.

Key Physical Checks for Horse Dehydration

You can check your horse for signs of equine dehydration using simple tests at home. These tests look at how well the body holds onto water.

The Skin Tent Test: Checking Elasticity

The horse skin tent test is a common way to check for dehydration. It checks how fast the skin snaps back into place.

How to Perform the Skin Tent Test

Find a spot on your horse’s neck, usually over the shoulder blade.
Gently pinch a fold of skin. You want to lift it slightly, like a small tent.
Let go of the skin quickly.
Watch how fast the skin goes back to normal.

What the Results Mean:

Not Dehydrated: The skin snaps back right away, in one second or less.
Mild Dehydration: The skin snaps back slowly, taking 2 to 4 seconds. This shows the horse needs water now.
Moderate to Severe Dehydration: The skin stays tented for 5 seconds or longer. This means the horse needs a vet right away. The longer it stays tented, the worse the dehydration is.

Checking the Gums: Capillary Refill Time

Checking the gums tells you about blood flow and hydration in the mouth. This test is called capillary refill time horse (CRT).

How to Check Capillary Refill Time

Lift your horse’s upper lip gently.
Press your finger firmly against the gums until the spot turns white.
Remove your finger quickly.
Time how long it takes for the pink color to return to the spot.

What the Results Mean:

Normal Hydration: Color returns in 1 to 2 seconds. Good blood flow is present.
Dehydrated: It takes longer than 2 seconds for the color to return. This shows that blood volume is low due to fluid loss.

Healthy gums should also look pink and feel slick or wet. If the gums look dry, pale, or sticky, it is another sign of trouble.

Examining the Eyes

One of the clear horse dehydration symptoms involves the eyes.

Sunken Eyes Horse Dehydration: When a horse is very dehydrated, the fat and tissue behind the eye lose fluid. This makes the eye look deep set or sunken into the socket. This is a sign of severe fluid loss.

Testing the Pinch in the Gums

You can also check the gums directly for wetness. Gently touch the gums above the front teeth.

Well Hydrated: Gums feel moist and slick.
Dehydrated: Gums feel sticky or dry to the touch.

Behavioral and Physical Clues

Besides the hands-on tests, your horse’s overall look and behavior give big clues.

Energy Levels and Behavior

A dehydrated horse often acts differently. Look for these changes:

Lethargy in Dehydrated Horse: The horse may seem unusually tired or weak. It might not want to move or stand up straight. Normal energy levels drop a lot.
Appears Depressed: The horse might look dull or unresponsive to its surroundings.
Loss of Appetite: A thirsty horse might not want to eat its feed.

Coat Condition

The condition of the hair coat changes when the body lacks water.

Dull Coat Horse Dehydration: A healthy coat shines. When dehydrated, the coat can look dry, rough, and lack its usual luster. It might stand up more easily when touched.

Other Body Signs

Keep an eye out for these other physical markers:

Thick Saliva: When you check the mouth, saliva may look thick, ropey, or like thick strings instead of thin and watery.
Muscle Cramps: Severe dehydration affects muscle function. Cramps can happen during or after exercise.
Increased Heart Rate: The heart may beat faster because it works harder to pump thicker, lower-volume blood.

Deciphering Lab Tests for Dehydration

Vets often use blood tests to confirm how bad dehydration is, especially if the horse is very sick.

Packed Cell Volume (PCV)

The packed cell volume horse dehydration test, also called a hematocrit, is very important. This test measures the percentage of red blood cells in the total blood volume.

How it Works: Red blood cells are solid parts of the blood. Water (plasma) is the liquid part. When the horse loses water, the total blood volume drops. But the number of red blood cells stays the same. This makes the blood look “thicker” or more concentrated.
Results: A high PCV number means the blood is too concentrated. A normal PCV is usually between 30% and 45%. A PCV over 50% strongly suggests dehydration. A very high PCV (like 60% or more) signals severe dehydration.

Total Solids (TS) Test

This test measures the total amount of protein and cells in the plasma. Like PCV, if the horse is dehydrated, the total solids measurement will be high because the water content is low.

Causes of Dehydration in Horses

Knowing why your horse is losing water helps you treat it and prevent it from happening again.

Poor Water Intake

Sometimes the simplest reason is the horse just isn’t drinking enough.

Cold Weather: Water can freeze in buckets or troughs. Horses drink less when the water is too cold.
Dirty Water: Horses refuse to drink water that looks dirty, smells bad, or has debris floating in it.
Water Source Issues: If automatic waterers break or troughs run dry, the horse has no option but to stop drinking.
Travel Stress: Horses often drink less when moving or staying in new places (like at a show).

Increased Water Loss

This happens when the horse loses too much fluid too quickly.

Heavy Work/Sweating: Intense exercise causes massive fluid loss through sweat. If not replaced, dehydration follows.
Diarrhea (Scours): This is a major cause. Fluid leaves the body rapidly through the manure.
Vomiting: Though less common in horses than in other animals, severe vomiting causes rapid fluid loss.
Fever: High body temperature increases water loss through breathing and sweating.
Excessive Urination: Certain illnesses, like kidney problems or Cushing’s disease, can cause a horse to pee too much.

Fathoming the Dangers of Dehydration

Dehydration is more than just being thirsty. It affects the whole body system.

Impact on Circulation

When the blood loses water, it becomes thick.

The heart must pump harder and faster to move this thick blood around.
This strains the cardiovascular system.
Less oxygen and nutrients reach the muscles and organs.

Impact on Digestion

The digestive tract needs water to work right.

Water helps break down food.
It keeps feed moving smoothly through the intestines.
Dehydration makes gut contents thick and slow. This hugely increases the risk of colic, especially impaction colic.

Impact on Cooling

Horses rely on sweat to cool down.

If dehydrated, the horse cannot sweat effectively.
This leads to overheating (heat stroke), which can be fatal very quickly.

Horse Dehydration Treatment: What to Do Next

If you find horse dehydration symptoms, you must act fast. The treatment depends on how severe the problem is.

Mild Dehydration Treatment

If the skin test is slow but the horse seems alert:

Offer Fresh Water: Make sure the water is clean and accessible. If the horse is reluctant to drink, try adding electrolytes to the water (check with your vet first for the right mix).
Offer Cool Water: Sometimes slightly cooler water encourages drinking.
Monitor Closely: Repeat the skin tent test and CRT every hour.

Moderate to Severe Dehydration Treatment

If the skin tent test is slow, the horse has lethargy in dehydrated horse, or the CRT is very slow:

Call the Veterinarian Immediately: Severe dehydration is a medical emergency. Do not wait.
Fluid Therapy: The vet will likely administer intravenous (IV) fluids. IV fluids quickly restore blood volume and hydration directly into the bloodstream.
Electrolyte Support: Fluids will contain necessary salts (electrolytes) lost through sweat or diarrhea.
Addressing the Cause: The vet will also treat the underlying problem, such as infection causing diarrhea or fever.

Important Note on Oral Rehydration: If a horse is severely dehydrated or has poor gut motility (a sign of serious illness), forcing large amounts of water by mouth can be dangerous. The fluid might not be absorbed well, or it could cause more stomach upset. Only use slow, voluntary drinking or vet-administered fluids in bad cases.

Preventing Dehydration: A Daily Plan

Prevention is always better than treatment when it comes to hydration.

Ensuring Constant Water Access

This is the most important step.

Check water sources at least twice a day, especially in very cold or very hot weather.
Clean all buckets and troughs regularly. Algae or dirt can make water unappealing.
For winter, use heated buckets or troughs to keep the water from freezing. Ensure the heater is safe.

Water During Exercise

Fluid loss during work is significant.

Offer small amounts of water frequently before, during, and after exercise.
If you ride for over an hour, give your horse a short break every 30–45 minutes to drink.
Use electrolyte supplements during long or hot rides to replace lost salts, which encourages the horse to drink more water.

Hydrating the Feed

You can boost water intake through feed.

Soaking hay pellets or sweet feed helps increase total water intake.
Adding water to the grain mash makes it appealing and hydrating.

Condition	Normal Hydration	Mild Dehydration	Severe Dehydration
Skin Tent Test	Snaps back instantly (<1 sec)	Slow return (2–4 sec)	Very slow (>5 sec)
Gums	Pink and moist	Slightly tacky/dry	Sticky or dry
Capillary Refill Time	1–2 seconds	3–4 seconds	>4 seconds
PCV (Hematocrit)	30–45%	46–50%	>50%
Energy Level	Alert and energetic	Slightly quiet	Lethargic, weak

Frequently Asked Questions (FAQ)

Can I give a dehydrated horse cold water?

Yes, but offer it slowly. If a horse is moderately dehydrated, cool (not ice-cold) water is usually fine. If the dehydration is severe, very cold water might shock the system or slow down gut motility, so vets often prefer temperature-neutral water initially or IV fluids.

How much water should a horse drink per day?

A typical adult horse needs about one gallon of water for every 100 pounds of body weight daily, under normal conditions. So, a 1,000-pound horse should drink about 10 gallons daily. This need increases with heat and work.

What is the danger of electrolyte overload?

While electrolytes are needed, giving too much can be harmful. Too many electrolytes can cause digestive upset (like diarrhea) or, worse, draw water out of the tissues into the gut, worsening dehydration if the horse cannot drink enough water to balance the salts. Always follow product instructions or vet advice.

Does a dull coat horse dehydration always mean they are sick?

A dull coat horse dehydration is a strong sign, but it is not the only cause. Poor nutrition or skin issues can also cause a dull coat. However, when paired with other signs like lethargy in dehydrated horse or slow skin tenting, dehydration is the most likely cause.

How fast can a horse become dehydrated?

In extreme heat, during heavy work without water breaks, or with severe diarrhea, a horse can become significantly dehydrated within just a few hours. This rapid loss emphasizes the need for constant vigilance.