Why Is My Horse Peeing and Pooping So Much?

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

Increased drinking and urination in horses often trace back to one of a few causes: pituitary pars intermedia dysfunction (PPID, also called Cushing's disease), chronic kidney disease, or a diet and management issue. Manure output is usually a separate story tied to how much forage your horse eats. If you are asking why is my horse peeing so much, the answer starts with measuring what is actually normal for your horse, then watching for changes in drinking, urine color, and manure consistency.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

• A healthy adult horse typically drinks 5 to 10 gallons of water a day and produces 2 to 4 gallons of urine, though this shifts with weather, work, and diet.
• The most common medical causes of true excessive urination (polyuria) and excessive drinking (polydipsia) in horses are chronic kidney disease, PPID, and psychogenic polydipsia with secondary polyuria [1].
• Manure output tracks forage intake. A horse eating more hay or grazing more grass will pass more manure, and that is often normal.
• A horse that stops peeing, strains to urinate, or dribbles small amounts needs same-day veterinary attention.
• Blood work and a urinalysis are the core tests your veterinarian will run to sort out the cause [2].

What Normal Looks Like and What a Problem Looks Like

Normal drinking and urination in horses

Horses are big animals with big water needs. A typical adult horse at rest drinks somewhere in the range of 5 to 10 gallons per day, and urine output runs roughly 2 to 4 gallons. Hot weather, hard work, lactation, and a high-salt or high-protein diet all push water intake up. A horse on fresh pasture may drink less because grass holds water.

Normal horse urine is cloudy and thick, often yellow to tan to brownish, because horses normally excrete a lot of calcium carbonate crystals and mucus. Clear, watery, dilute urine is actually the abnormal finding in a horse, not the normal one [3].

Normal manure output

A 1,000-pound horse eating a forage-based diet passes manure 8 to 12 times a day, sometimes more. If your horse is on free-choice hay, on lush pasture, or getting more feed than usual, expect more piles. Softer, more frequent manure can also follow a diet change, spring grass, or a course of antibiotics.

What actually counts as "too much"

The number that matters is a change from your horse's own baseline. If your horse normally drains one bucket overnight and now drains three, that is a signal. If the stall has gone from a few wet spots to a soaked floor every morning, that is a signal. Owners often notice this before anything else looks wrong.

Why Is My Horse Peeing So Much? The Main Causes

Polyuria (excessive urine production) and polydipsia (excessive drinking) usually travel together. When a horse drinks more, it pees more. When a horse pees more for a medical reason, it drinks more to replace the fluid. Untangling which came first is part of what your veterinarian does [4].

PPID (pituitary pars intermedia dysfunction)

PPID is one of the most common reasons an older horse starts drinking and urinating more [1]. The pituitary gland overproduces hormones that disrupt normal regulation, and the kidneys respond by dumping more water. You may also see a thick, curly coat that does not shed, loss of topline muscle, a pot belly, and laminitis. PPID is manageable with medication and monitoring, and catching it early makes a real difference.

Chronic kidney disease

Chronic kidney disease is rare in horses, with a reported prevalence of about 0.12% [5]. When it does happen, the most common signs are vague: weight loss, polyuria and polydipsia, and swelling under the belly [5]. Creatinine only rises once at least two-thirds of kidney function is gone, so early disease can hide behind normal-looking blood work [5]. Your veterinarian may need a more sensitive test, such as an iohexol clearance study combined with a urine protein measurement, to get a real picture of kidney function [5].

Acute kidney injury

Acute kidney injury comes on fast. Common triggers include nephrotoxic drugs (some antibiotics and anti-inflammatories) and conditions that reduce blood flow to the kidneys, such as dehydration, shock, or severe colic [6]. Leptospira infection is the most common infectious cause [6]. Horses with a polyuric form of acute kidney injury often do well with aggressive fluid therapy, while horses that stop producing urine have a much poorer outlook [6]. This is an emergency.

Psychogenic polydipsia

Some horses drink out of boredom, habit, or stress, especially if they are stalled with nothing to do. They drink far more than they need, and the kidneys dutifully produce more urine. This is a diagnosis of exclusion, meaning your veterinarian has to rule out PPID, kidney disease, and other causes first [1]. Management usually involves more turnout, more forage, and sometimes restricting water access under veterinary supervision.

Diet, salt, and workload

A horse on a high-salt diet, a high-protein diet, or a heavy sweat-inducing workload will drink and pee more. So will a horse that suddenly gets more forage. This is often normal physiology, not disease. The trick is to look at the whole picture: is the horse eating, working, and behaving normally, or is something else off?

Manure output and diet

If your horse is pooping more, look at the feed first. More hay, more pasture, more grain, or a recent diet change all increase manure volume. Loose or watery manure, manure with a foul smell, or manure with undigested grain suggests a digestive problem, not just a big appetite. Horses with chronic kidney disease can also develop diarrhea, though it is a less common sign [5].

Red Flags That Make It an Emergency

Call your veterinarian right away if you see any of these:

• Your horse is straining to urinate, posturing repeatedly, or passing only dribbles.
• Your horse has not urinated in 12 hours or more.
• The urine is dark red, brown, or bloody.
• Your horse is colicky, sweating, or rolling.
• Your horse has stopped eating or drinking entirely.
• Your horse is depressed, weak, or has a fever.
• Your horse's gums are pale, dry, or tacky.

A horse that cannot pass urine can rupture its bladder. That is a life-threatening emergency. Do not wait to see if it resolves on its own.

Safe Things You Can Do at Home While You Wait

You cannot diagnose this at home, but you can gather information that helps your veterinarian.

Measure water intake. Fill a known volume, such as a 5-gallon bucket, and track how much your horse drinks over 24 hours. Do this for two or three days if you can.

Watch the stall or paddock. Note how many wet spots you see and how large they are. Take a photo of the urine if the color looks off.

Check the manure. Count piles, note consistency, and look for undigested feed, parasites, or blood.

Keep a simple log. Write down feed, hay, turnout, work, weather, and any medications. This history is exactly what your veterinarian needs [2].

Do not restrict water unless your veterinarian tells you to. A horse that is peeing a lot because of kidney disease still needs to drink.

Do not give any medication without asking your vet first. Some common drugs are hard on the kidneys [5].

If you want to compare notes with what owners of other species see, our guides on why a dog pees so much and why a dog drinks so much water cover similar patterns in dogs, though the causes differ by species.

What Your Veterinarian Will Check and Test

Your veterinarian will start with a full history: how much your horse drinks, how often it urinates, what the urine looks like, what medications it takes, appetite, diet, weight changes, and past illnesses [2]. Then comes a physical exam, including hydration status, body condition, and a check for swelling under the belly.

Blood work is the next step. A chemistry panel looks at kidney values (creatinine, BUN), electrolytes, and blood protein. A complete blood count checks for infection or inflammation. A urinalysis looks at urine concentration, crystals, protein, and cells [2].

If PPID is suspected, your veterinarian may run a hormone test such as baseline ACTH or a dexamethasone suppression test. If kidney disease is suspected, an iohexol clearance test gives a more accurate measure of kidney function than creatinine alone [5].

Endoscopy can be useful too. A small flexible tube with a camera is passed through the urethra to look at the urethra and sometimes the bladder, which helps identify obstructions, tumors, or malformations [2].

In some cases, your veterinarian may recommend a kidney biopsy or imaging such as ultrasound. The exact plan depends on what the initial tests show.

Prevention and Monitoring

You cannot prevent every cause of increased urination, but you can lower risk and catch problems early.

Know your horse's baseline. Track normal water intake and manure output for a week when your horse is healthy. That gives you a reference point.

Schedule annual exams for older horses. PPID becomes more common with age. Early detection lets you start treatment before laminitis or muscle loss sets in.

Watch medications. Some drugs are nephrotoxic, meaning they can damage the kidneys [6]. Ask your veterinarian about kidney-safe alternatives when your horse needs long-term pain relief or antibiotics.

Manage diet carefully. Sudden increases in grain, rich pasture, or salt can all change drinking and manure output. Make changes gradually.

Keep water clean and available. Horses drink more when water is fresh. That is fine. What matters is whether the increase is sudden and unexplained.

Monitor for subtle signs. Weight loss, a dull coat, poor performance, and swelling under the belly can all point to kidney problems before blood work changes [5].

If you are also managing a dog with similar symptoms, our article on dog urinating a lot and drinking a lot walks through the same logic for a different species.

Limitations and When to Contact a Veterinarian

This article cannot tell you what is wrong with your specific horse. Only a veterinarian who examines your horse and runs tests can do that.

Call today (same day): Your horse is drinking and peeing much more than usual, has lost weight, has a poor appetite, or has swelling under the belly. These signs need blood work and a urinalysis.

Go emergency now: Your horse is straining to urinate, has not urinated in 12 hours, has bloody or dark urine, is colicky, is not eating or drinking, or is depressed and weak.

Routine visit: Your horse is older and showing a long coat, muscle loss, or laminitis along with increased drinking and urination. This can wait for a scheduled appointment, but do not put it off for weeks.

Horse not peeing much: This is a different problem from peeing too much, and it is often more urgent. A horse that is not passing urine may have an obstruction or a bladder problem. Call your veterinarian right away.

Frequently Asked Questions

How much water should a horse drink per day?

A typical adult horse drinks about 5 to 10 gallons of water per day, though this varies with weather, work, and diet. Hot weather, lactation, and heavy exercise all increase needs. If your horse is drinking noticeably more than its usual amount for more than a day or two, have your veterinarian check it.

Why is my horse drinking and peeing so much?

The most common medical causes are chronic kidney disease, PPID, and psychogenic polydipsia with secondary polyuria [1]. Diet, salt intake, and workload can also play a role. Your veterinarian will use blood work and a urinalysis to narrow it down.

Why does my horse poop so much?

Manure output follows forage intake. A horse on free-choice hay or lush pasture will pass more manure than one on a measured diet. If the manure is loose, foul-smelling, or contains undigested grain, that points to a digestive issue instead of a normal increase.

Can a horse pee too much from stress?

Yes. Psychogenic polydipsia is a real condition in horses, often linked to boredom or stress in stalled horses [1]. It is diagnosed only after medical causes are ruled out. More turnout and more forage often help.

When should I call the vet for a horse that is peeing a lot?

Call your veterinarian if the increase is sudden, if your horse is also losing weight or eating less, or if you see swelling under the belly. Call immediately if your horse is straining to urinate, has not peed in 12 hours, or has bloody or dark urine.

Related Articles

• Why Is My Dog Peeing So Much?
• Why Is My Dog Drinking So Much Water?
• Dog Urinating a Lot and Drinking a Lot: What It Could Mean
• Dog Urinating Frequently: Causes and When to Call the Vet
• Dog Urinating More Frequently: When to See the Vet
• Why Is My Dog Panting So Much?

References

1. Polyuria and Polydipsia in Horses. The Veterinary clinics of North America. Equine practice, 2022.
2. Detecting Disorders of the Kidneys and Urinary Tract in Horses - Horse Owners. Merck Veterinary Manual.
3. The Urinary System of Horses - Horse Owners. Merck Veterinary Manual.
4. Polyuria and polydipsia in horses. The Veterinary clinics of North America. Equine practice, 2007.
5. Chronic Renal Failure-Causes, Clinical Findings, Treatments and Prognosis. The Veterinary clinics of North America. Equine practice, 2022.
6. Acute Kidney Injury and Renal Failure in Horses. The Veterinary clinics of North America. Equine practice, 2022.

Further Reading

• Noninfectious Diseases of the Urinary System in Horses - Horse Owners (Merck Veterinary Manual)
• Merck Veterinary Manual: Horse Owners