There’s a lot more to manure than mucking; your horse’s fecal production and appearance can be an indicator of good or poor health.

Potty talk is largely taboo among adults, but it shouldn’t be! There are tons of tidbits to share with friends and colleagues about poop (Did you know you can harness the heat generated by composting horse manure to warm your barn in winter?)—almost as much as the nine tons of manure the average 1,000-pound horse produces each year.

So don’t regard horse poop as just a pain in the butt to muck, pick up, and dispose of. Rather, consider it a valuable window into your horse’s gut and overall health status.

“A horse’s intestinal tract is approximately 100 feet long and finely adapted for various functions, but it’s also prone to development of problems. Things can go wrong quickly,” warns Scott Weese, DVM, DVSc, Dipl. ACVIM, a professor in the Department of Pathobiology at the University of Guelph’s Ontario Veterinary College, in Canada.

In this article we will describe the importance of knowing what your horse’s normal manure looks like, and being able to identify dry feces, diarrhea, and even signs of dental and parasite issues, before a major problem develops.

Picture Perfect

If you consider fecal production one of your horse’s vital signs, along with temperature and heart and respiratory rates, then it is crucial to know your horse’s normal manure production frequency and appearance. This will help you rapidly recognize when something unusual is afoot.

While every horse’s fecal production differs, ideally you want to see well-formed fecal balls with noticeable stems but no real “chunks” of food, fairly uniform color, little odor (compared to carnivores such as cats or dogs), and no mucus covering. A small amount of liquid either immediately prior or following a bowel movement might also be normal.

Lori K. Warren, PhD, PAS, an associate professor at the University of Florida’s Department of Animal Sciences, shares her observations about manure production:

  • Each equine defecation lasts about 15 seconds;
  • Defecation frequency can depend on the horse’s age, sex, and diet; and
  • On average, mares and geldings defecate six to eight times per day, but stallions and foals can double that frequency.

In some instances, defecation is social in purpose. For example, Warren says feces can provide horses with information about other animals’ social and reproductive status. When one horse eliminates, it can induce others in the social unit to follow suit. And it’s common to see stallions frequently marking other horses’ fecal piles.

Too Moist

If you’ve ever had a bought of diarrhea, you know it can herald the arrival of a virus, an infection, or any number of nasties that leave you reaching for the Imodium and heading to bed. Weese says that a horse with diarrhea doesn’t always have a health issue, but never take your horse’s case of the runs lightly.

“Sometimes it’s just a cosmetic issue, but at other times it can indicate a life-threatening problem (e.g., due to salmonella or a Clostridium bacteria in young foals),” he notes. “Determining the cause for the diarrhea is important, but often difficult, especially with mild, chronic disease.”

Weese groups diarrhea in horses into four main categories:

1. Infectious e.g., due to bacterial infections such as salmonellosis, clostridiosis, and equine proliferative enteropathy caused by Lawsonia intracellularis;

2. Inflammatory “Inflammatory bowel disease, a common problem in people, rarely causes diarrhea in horses since the large colon (which largely controls fecal consistency in adult horses)is not commonly affected; however, inflammatory diseases can occur,” Weese notes;

3. Cancerous “Intestinal cancer such as lymphoma usually causes weight loss more often than diarrhea, but always needs to be considered with chronic disease,” he adds; or

4. Management-related.

Many owners and farm managers know to avoid making sudden changes to their charges’ diets and to let the gastrointestinal system “adapt” to a new diet gradually.

“Changes in diet in addition to other management factors can be associated with development of diarrhea, but this type of diarrhea is usually transient and not associated with any other problems.” relays Weese. “Just ‘loose’ manure is not really a problem; however, when you consider the massive ability of the horse’s colon to absorb water, something pretty major has to be happening in the colon to cause significant changes in fecal consistency.”

Weese’s advice for owners of horses with runnier manure than usual: When in doubt, call a vet.

“I think it’s especially important to address loose manure in a young foal that can dehydrate quickly or when there’s any concurrent change in clinical condition such as attitude or appetite,” he adds.

Too Dry

Constipation per se does not really occur in horses and is more commonly referred to as an impaction, falling under the colic category. Sometimes, however, a horse’s manure does appear drier than usual.

“Inadequate water access is probably the most common cause of dry feces,” says Weese.

The average horse drinks 5 to 10 gallons per day, but this varies depending on the individual horse and the environment (e.g., temperature, humidity). And the environment can dictate water availability, particularly in northern climates where water freezes in the winter. Other factors that can potentially contribute to decreased water intake include shipping, stress, and pain. Those same factors can negatively impact gut motility, possibly leading to impactions.

“Adequate exercise is also important for gut health, and restriction of horses to a stall can be associated with decreased intestinal motility,” Weese says.

Too Gritty

Sand colic and impactions most commonly occur in areas where horses graze on sandy soil pastures or eat off ground that is predominantly sand or fine gravel. To help determine if a horse has sand in his feces, owners can follow this simple recipe:

1. Place six fecal balls in a glass jar.

2. Fill the jar half full with water and shake well, then let it settle for 15 minutes.

3. If there is sand lining the jar, it might indicate your horse is consuming sand but passing it easily.

4. If there is no sand, either your horse is not consuming substantial amounts of sand, or he’s not passing the sand he’s ingesting, putting him at risk for colic.

Still confused about your horse’s sand intake? Call your veterinarian. He or she can use a stethoscope to listen to your horse’s gastrointestinal tract. Intestines that contain sand, despite little to no sand appearing following the “jar test,” sound like waves hitting an ocean shore. The veterinarian can suggest management options for these horses, such as increasing exercise or administering psyllium or mineral oil.

Color Coding

Did you know that the carriage horses used in Prince Charles and Lady Diana’s wedding consumed pastel-colored dyes so their manure would match the wedding’s color scheme? While most of us will never find Easter-egg-hued fecal balls in our horses’ paddocks or stalls, there are times when manure does come out an interesting shade or texture.

Warren assures us that many things—mostly benign—could cause colorful manure:

  • Alfalfa generally results in very green fecal balls;
  • High beet pulp intake can lead to reddish-brown fecal balls and a sticky, clear film around the ball;
  • For a horse unaccustomed to vegetable oil, too much can make his feces appear loose, grayish, and oily; and
  • Mucus covering the fecal balls indicates delayed passage (e.g., impaction).

Two colors that warrant a double take at your horse’s piles (and a call to your vet) are red and black. “Red feces or feces with flecks of blood can indicate bleeding in the lower gastrointestinal tract, such as (from a) rectal tear,” Weese explains.

In contrast, black feces (with the exception of neonate meconium—a newborn’s near-black and pelleted first manure) indicate the horse could be bleeding from a higher point in the gastrointestinal system and blood has been digested before being excreted.

“Black feces is something that we don’t usually see, even with significant bleeding, unlike in other species (such as dogs and cats),” Weese assures.

Dental Issues

Dental problems purportedly alter the appearance of a horse’s manure. For example, large or undigested feed particles (such as whole grains) might be noticeable if a horse isn’t chewing his food sufficiently.

“There is some evidence in the literature that poor dentition results in an increase in long stems of roughage in the manure,” notes Robert M. Baratt, DVM, MS, FAVD, a part-time resident in dentistry at Cornell University’s College of Veterinary Medicine and practitioner at the Salem Valley Veterinary Clinic, in Connecticut.

Although many veterinarians suggest that dental flotation can remedy this situation, Baratt says, “There is actually poor evidence to support the validity of occlusal equilibration (floating) having a direct effect on fiber length in the manure.”

James L Carmalt, MA, VetMB, MVetSc, FRCVS, Dipl. ABVP, ACVS, associate professor of Large Animal Surgery at the University of Saskatchewan, and colleagues conducted a study in 2004 evaluating feed digestibility and fecal particle size in healthy pregnant mares. They found no significant difference in digestibility and particle size between horses that did and did not have dental procedures performed. The team suggested that dental floating does not result in significant short-term changes in body weight, body condition score, feed digestibility, or fecal particle size in the horses studied, but they noted additional studies were warranted to determine the clinical utility of regular dental floating in apparently healthy horses.

Nonetheless, Baratt recommends owners have an equine veterinary dentist perform a thorough oral examination on their horses annually.

Particularly in older horses, normal tooth attrition can result in loss of the reserve crown (the portion of tooth still within the jaw bone that has not erupted). “Such horses can no longer effectively chew forage,” Baratt says. “Fortunately, with the ready supply of senior feeds, these horses can be managed quite well.”

Poop and Parasites

Any article on poop must include at least a token discussion of internal parasites; they can cause changes in manure consistency, they spend time in feces as part of their life cycles (though you might not be able to see them), and their population numbers in your horse’s poop can help you make smart deworming decisions to help prevent parasite resistance.

Roundworms, strongyles, and tapeworms, among others, can cause myriad health issues such as chronic diarrhea, poor coat, weight loss, and even colic. Thus, managing internal parasites is an important consideration for all horse owners/managers.

Because these parasites are developing resistance to multiple anthelmintic classes, veterinarians have been urging owners to abandon traditional calendar-based deworming protocols. No new dewormer classes are likely to be available in the near future, which means owners must consider alternate deworming strategies to prolong the life-span of the available anthelmintics. This includes running routine fecal egg counts on horses to determine which animals require deworming.

Take-Home Message

Critically assessing your horses’ movements (and I don’t mean gaits) on a daily basis is essential.

“What your horse eats can affect the color and consistency of the feces,” Warren emphasizes. “Know what is normal for your horse. To maintain the consistency of manure, be sure to gradually adapt your horse to new feeds, hays, and pasture turnout. When you do make a change to the diet, monitor your horse’s manure because it can be an indicator of digestive upset.”