Key Insights
  • Horses produce 35–50 pounds of manure daily, making observation a useful health check
  • Normal manure is brown, moist, well-formed into fecal balls, and breaks apart easily
  • Loose or watery manure may reflect diet changes but persistent diarrhea suggests illness
  • Dry, hard manure can signal dehydration, slow gut transit, or early colic
  • Abnormal colors—black, red, or yellow—may indicate ulcers, bleeding, or liver disease
  • Gritty texture suggests sand ingestion; visible feed signals chewing or digestion issues

When you have horses, dealing with manure is simply a fact of life. After all, an average-sized horse defecates anywhere from 4 to 13 times each day. This means each horse produces approximately 35 to 50 pounds of manure per day. [1]

Other than cleaning stalls and paddocks, horse owners may not pay too much attention to their horse’s manure. However, manure can provide quite a bit of information about your horse’s health, especially when it comes to their digestive system.

It’s good to get in the habit of doing a daily check of your horse’s manure. This will not only help you understand what’s normal for your horse, but also allow you to catch any potential problems early on.

Continue reading to learn about different appearances of manure and what this can tell you about your horse. If you observe any sudden changes or if your horse’s manure appears abnormal, this can indicate a health concern. Contact your veterinarian if you are concerned about changes in your horse’s bowel movements.

What Does Healthy Horse Manure Look Like?

Manure has several identifying characteristics that can relay information about a horse’s health. These characteristics include consistency, color, odor, and overall appearance. When evaluating your horse’s manure, keep these characteristics in mind and compare against what is normal for your horse.

Since healthy horse manure can vary based on diet and age, regular monitoring is key to understanding each horse’s individual health indicators.

Consistency

Normal horse manure should appear as well-formed fecal balls that are moist and easily breakable. Manure that is hard and dry or that is very loose and watery can both be signs of a problem.

With that said, occasional loose manure may simply reflect a recent change in diet. This can happen in spring when green grass begins to come in. Loose manure may also occur when moving a horse to a new pasture with different grasses or more fulsome, diverse plant growth. [2]

Color

The color of your horse’s manure reflects the contents of their diet and how well they’re digesting food. In some cases, unusual color is an indication of medical concern. The following are all colors that you might see in a horse’s manure: [3][4][9]

Brown

A brown color is considered normal and suggests the horse’s digestive system is functioning as it should. Brown manure indicates your horse is eating an appropriate diet and is absorbing nutrients properly.

Green

Green manure usually indicates undigested plant material in the gut. This color may be considered normal when horses are eating lush, green pasture or some types of hays with high chlorophyll content such as alfalfa. Green manure usually isn’t a problem unless it occurs in conjunction with diarrhea.

Black, Tarry, or Abnormally Dark

In newborn foals, passing black feces, known as meconium, is normal. Black or dark manure being passed by an older horse may indicate gastrointestinal bleeding, which could arise from severe gastric ulcers or other causes.

If you notice black or tarry manure coming from your mature horse, contact your veterinarian right away.

Red or Bloody

Red coloring or signs of blood in manure means that your horse may be experiencing substantial bleeding in the right dorsal colon and/or small colon. Other causes of red or bloody manure include colitis, parasites, or rectal tears. Red or bloody manure is another cause for immediate veterinary attention.

Keep in mind that a high beet pulp intake can also cause manure to take on a reddish-brown color. In such cases, fecal balls may also have a clear film around them. If you are unsure of the cause of your horse’s red manure, having it checked by your veterinarian is always a good idea.

Yellow

Yellow manure can be a sign of liver disease or restricted bile flow, which usually indicates difficulty digesting fats in the diet. However, horses on a high-fat or high-grain diet may also have yellowish manure.

If your horse has yellow manure and is lethargic or shows any other changes in their behavior, seek prompt veterinary care.

Other Colors

Sometimes horse manure can appear in other colors such as gray, orange, or even purple. These colors are usually caused by specific medications, supplements or feed additives. However, if the color changes occur with other symptoms, contact your veterinarian.

Color Status Possible Causes Requires Medical Attention
Brown Normal Manure from a healthy horse should be brown and well formed No
Green Normal Undigested plant material, resulting from eating lush grasses No
Black or Tarry Normal in newborn foals;
Abnormal otherwise		 In foals, black meconium is the first stool passed after birth
Otherwise, could point to bleeding high in the GI tract		 Yes, except for meconium
Red or Bloody Abnormal Bleeding in the GI tract, such as from ulcers or rectal tears Yes
Yellow Abnormal Biliary system dysfunction leading to improper digestion of fats Yes
Other Colors Variable Certain medications or feed additives Yes

Odor

Healthy horse manure should not have a strong or offensive odor, but it may smell slightly earthy or like hay or grass. If there is an unusually strong or foul odor, this could indicate a digestive problem or infection that needs to be investigated.

Overall Appearance

Healthy, fresh horse manure should be moist, well-shaped into distinct fecal balls, and maintain its form, indicating proper hydration and digestive function.

Fecal ball size can differ based on the size of the horse, with ponies and smaller breeds producing smaller fecal balls compared to larger breeds. It’s important to know the normal fecal ball size for your horse to detect any changes.

It can be helpful to think of stool quality as a spectrum. This manure scoring chart can help horse owners evaluate where on the spectrum their horse’s stool lies. [15]

Stool Score Name Description Requires Medical Attention
1 Watery Diarrhea Stool is more water than solid. Horse may not have any control over defecation (a.k.a. “firehose” diarrhea) Yes, urgently
2 Diarrhea Stool is very wet, does not hold its shape. May be malodorous Yes
3 Soft, Unformed Stool has some shape but is difficult to pick up Yes, if persistent
4 Soft, Formed Normal manure No
5 Firm, Formed Manure is formed and dry, may start to crumble when picked up No, but watch for progression of symptoms
6 Hard, Dry Manure is very crumbly. Horse may have difficulty defecating Yes, especially if horse has difficulty defecating or shows early signs of colic

If your horse’s manure consists of fecal balls that are smaller than normal, this may indicate prolonged transit time through the descending colon. If this is the case, the fecal balls are often covered in mucus and appear slimy. [4][5]

Horses with dental issues may have large or undigested feed particles in their manure. You may observe whole grains or pieces of grass or hay in the feces. Undigested feed particles are more common in older horses with worn or missing teeth, contributing to improper chewing.

What Does Abnormal Horse Manure Look Like?

It’s normal for your horse’s manure quality to show slight variations due to changes in seasons, diet, exercise routines, and other lifestyle factors over the course of the year.

However, sudden or prolonged changes might indicate an underlying health issue affecting your horse. Knowing the signs of abnormal horse manure is helpful so you can recognize when it’s time to call your veterinarian for help.

Diarrhea

Diarrhea in horses is characterized as an increased frequency of defecation with increased water content in the feces. [9] Extremely loose and watery manure is abnormal and can occur for a variety of reasons, often illness related.

This condition can be linked to changes in intestinal blood flow and electrolyte imbalances due to fluid retention within the intestines. [6]

Horses may develop diarrhea due to bacterial infections, parasites, treatment with antibiotic medications, or other conditions affecting nutrient absorption in the gut.

Antibiotic Therapy

Antibiotics can cause loose stools and/or diarrhea since these medications kill off both “good” and “bad” bacteria in the gut. While this type of diarrhea isn’t usually dangerous, it is important to monitor the horse’s condition. If it persists, contact your veterinarian for guidance.

Diarrhea associated with antibiotics should clear up after the horse finishes their course of medication. Adding probiotics to the horse’s diet following treatment is a good idea to support the horse’s gut microbiome.

Bacterial Infections

Diarrhea in horses can result from various bacterial infections, which often involve other symptoms and typically require antibiotic treatment. Infections may be caused by: [4][6]

Always consult with your veterinarian if you suspect your horse has developed a bacterial infection.

Parasites

High internal parasite loads may also lead to diarrhea in horses, often in conjunction with weight loss and poor body condition. Several parasites that may cause diarrhea in horses include: [3][4][8]

  • Cyathostomes
  • Parascaris spp.
  • Cryptosporidium spp.
  • Tapeworms

If parasites are suspected, a fecal egg count can be performed by taking a sample of your horse’s manure to your veterinarian or sending it to a laboratory that does this type of test. Fecal egg counts can help you determine which dewormer to use and also indicate if your ongoing deworming routines are effective. [8]

Viruses

Diarrhea in horses may also be caused by viruses such as equine coronavirus (ECoV), rotavirus, and protozoal infections. [4][6]

Viruses often do not respond to treatment and need to run their course, but your horse may need supportive care to avoid severe illness.

Malabsorption Syndromes

Malabsorption syndromes, characterized by inadequate nutrient absorption in the intestines, can also cause diarrhea in horses. These conditions often present with additional symptoms like weight loss, colic, lethargy, and dermatitis. [3]

Malabsorption in horses isn’t common, but can arise from issues in the intestinal mucosa’s ability to absorb or transport nutrients, often due to structural or functional abnormalities in the small intestine. Malabsorption syndromes can also involve complications in related organs such as the pancreas, liver, and biliary tract. [3]

Diarrhea in Foals

Diarrhea is one of the most common health concerns in young foals, affecting more than half of all foals before they are of weaning age. [9]

Diarrhea is even more concerning in foals because their bodies are less resilient to fluid and electrolyte imbalances, making them more vulnerable to dehydration and its associated complications.

Additionally, foals have less developed immune systems, increasing their risk of severe infections and complications from diarrhea-causing pathogens. Prompt veterinary attention is crucial to prevent potentially life-threatening issues in foals with diarrhea.

Common causes of diarrhea in foals include: [9]

Foal heat diarrhea is a common condition that occurs in foals aged 4-15 days and normally lasts for 3-4 days. It is believed to be caused by changes in the mare’s milk or intestinal flora during foal heat, which refers to the first estrous cycle that a mare experiences after giving birth.

Foal heat diarrhea is usually a self-limiting condition; these foals show no other signs of illness and continue to nurse well. [9]

Dry, Hard Stools

If your horse’s manure is overly dry, it might be a sign of dehydration or insufficient water intake. Hard, dry stools can indicate that the digestive process is slower than normal, which can sometimes be an early warning sign of colic.

Colic in horses, characterized by abdominal pain, can stem from various factors, including: [8][10][11]

Dry, hard manure may also be covered in mucus, which is another sign of slow gastrointestinal transit time. If your horse has dry, hard, and/or mucus-covered manure and shows other symptoms of colic, such as going off feed, lying down more than normal, or rolling, call your veterinarian right away.

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Gritty Manure

Gritty manure is often due to high sand content in the feces. It’s not unusual for horse manure to contain small amounts of sand, soil, or gravel. Horses sometimes ingest small amounts of these materials while grazing or feeding from the ground.

However, if there is a significant amount of sand in the manure, your horse likely has accumulated sand in their colon, which can result in life-threatening sand impaction. [4][12] Contact your veterinarian to obtain an accurate diagnosis and treatment plan.

Visible Parasites

Horses are constantly exposed to different internal parasites, making the presence of some parasites in the gastrointestinal tract a normal occurrence. These parasites can lay millions of eggs per day that are excreted in manure.

While these eggs are too small to be seen without a microscope, it is possible, though rare, to find whole worms or parasites in a horse’s manure. If you do find visible parasites, it’s advisable to collect the manure sample in a sealable bag and bring it to your veterinarian for analysis.

Based on this, your veterinarian can suggest a suitable deworming treatment, such as Ivermectin paste.

Frequently Asked Questions

Here are some frequently asked questions about horse manure and health:

Summary

It’s important for horse owners to regularly check their horse's manure for normal color and consistency. Frequent monitoring not only establishes a baseline for your horse, but also helps identify digestive problems or illnesses early on. Keep these points in mind when evaluating your horse's manure:

  • Healthy horses have manure that consists of well-formed, brown, moist, and easily breakable fecal balls
  • The color of manure can vary with dietary changes, especially if feeding high amounts of alfalfa or beet pulp
  • Slight changes in your horse’s manure are to be expected during times of stress, when changing the diet or during a course of antibiotics
  • Diarrhea, overly dry and hard stools, gritty manure, and visible parasites all warrant veterinary attention
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References

  1. Westendorf, M. Horses and Manure. Rutgers New Jersey Agricultural Experiment Station. 2004.
  2. Geor, R.J. and Harris, P.A. How to Minimize Gastrointestinal Disease Associated With Carbohydrate Nutrition in Horses. AAEP Proceedings. 2007.
  3. Mair, T.S. et al. Malabsorption syndromes in the horse. Equine Veterinary Education. 2006.
  4. Sanchez, L.C. Disorders of the Gastrointestinal System. Equine Internal Medicine. 2018.
  5. Malone, E. Colic in Your Horse. University of Minnesota Ext. 2021.
  6. Shaw, S.D. and Stämpfli, H. Diagnosis and Treatment of Undifferentiated and Infectious Acute Diarrhea in the Adult Horse. Vet Clin North Am Equine Pract. 2018.
  7. Arnold, C. et al. Alterations in the Fecal Microbiome and Metabolome of Horses with Antimicrobial-Associated Diarrhea Compared to Antibiotic-Treated and Non-Treated Healthy Case Controls. Animals (Basel). 2021. View Summary
  8. Buono, F. et al. Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections. Parasitology. 2023. View Summary
  9. Oliver-Espinosa, O. Foal Diarrhea: Established and Postulated Causes, Prevention, Diagnostics, and Treatments. Vet Clin North Am Equine Pract. 2018.
  10. Lara, F. et al. Changes in the gut microbiome and colic in horses: Are they causes or consequences?. Open Vet J. 2022. View Summary
  11. Scherrer, N.M. et al. Interval prevalence of and factors associated with colic in horses hospitalized for ocular or orthopedic disease. AVMA. 2016.
  12. Kendall, A. et al. Radiographic parameters for diagnosing sand colic in horses. Acta Veterinaria Scandinavica. 2008. View Summary
  13. Patangia, D.V. et al. Impact of antibiotics on the human microbiome and consequences for host health. Microbiologyopen. 2022.
  14. Leibsle, S. Cold Weather Colic. AAEP. 2016.
  15. FeedXL Horse Nutrition Calculator. Manure Score Chart: How to Quickly Check Your Horse’s Hindgut Health.