Why Does a Horse Eat Manure?

Horses often do something called coprophagia, which means they eat manure. This behavior often confuses and worries horse owners. There are, however, a number of reasons a grown horse might eat feces. Horse owners can help their horse’s health and well-being by stopping this bad habit by learning about its possible causes.

An Innate Behavior in Foals

Foals naturally eat their mother’s manure starting from a few hours after birth. This serves an important purpose – to inoculate the foal’s digestive system with essential microbes and bacteria needed to properly ferment fiber and digest solid foods. Newborn foals have a sterile gastrointestinal tract so they rely on ingesting microflora from the dam’s manure to populate their gut and establish a healthy microbial balance. This early coprophagia sets up the foal for proper hindgut function and digestion of hay and grains as they mature. Therefore manure eating in young foals is considered normal and beneficial.

Nutritional Deficiencies

Adult horses often eat manure to make up for nutrients they aren’t getting from their food. Manure has fiber, proteins, vitamins, and minerals that have already been digested but are still there. If a horse isn’t getting enough of certain nutrients, it may try coprophagia to get those nutrients back from the feces.

Specific nutrient deficiencies that could drive manure eating include:

• In order to stay healthy, horses need to eat at least 2% of their body weight every day. Not getting enough roughage makes animals hungry and makes them want to find more fiber-rich foods.

• Protein: Diets very low in protein cause protein-seeking behavior like coprophagia.

• Vitamins: Deficiencies in B vitamins and vitamin K are linked to manure eating in horses.

• Minerals: Imbalances in the calcium-phosphorus ratio or inadequate magnesium, salt or potassium can trigger coprophagia.

Correcting the diet to provide adequate nutrients tailored to the individual horse is key to curbing this habit.

Imbalanced Hindgut Microbiome

The large intestine houses a complex population of bacteria and microorganisms that ferment fiber and deliver nutrients to the horse. When this microbial balance is disrupted, horses may eat manure in an effort to replenish missing gut flora. Some common triggers of microbiome disruption include:

• Sudden diet changes
• High starch intake
• Stress
• Illness
• Antibiotics
• Aging
• Parasites

Probiotics, prebiotics and gradual diet adjustments can help normalize the hindgut microbiome. Reducing starch, providing ample fiber and limiting stress also supports healthy gut flora.

Boredom/Stereotypy

Horses are highly routine-oriented animals. When their normal routine is thrown off, they are confined, and they don’t get enough exercise, they often get bored. Horses that are bored can develop stereotypies, which are patterns of behavior. One example of a stereotypy is coprophagia. Horses that are kept in stalls and don’t get much time outside are more likely to eat manure because they are bored and angry.

Increasing turnout, providing toys and slow-feed hay nets are simple ways to combat boredom and destructive behaviors. Avoiding confinement and solitude while maintaining a consistent daily routine also helps minimize boredom.

Medical Conditions

Though rare, certain medical conditions are associated with increased manure eating in horses:

• Dental disease: Misaligned teeth make chewing hay difficult, so horses may turn to manure for fiber intake. Regular dental exams help detect dental problems.

• Gastrointestinal disease: Conditions like ulcers and colic cause significant gut pain and distress, which may lead horses to ingest manure seeking relief.

• Hindgut acidosis: Too much starch and sugar fermented in the large intestine causes hindgut acidosis. Horses may eat manure to buffer the acidic gut pH.

• Equine motor neuron disease: This neurologic disease causes vitamin E deficiency and abnormal eating behaviors like coprophagia.

Diagnosing and addressing any underlying medical issues is key to stopping manure eating associated with disease.

Preventing Coprophagia

While occasional manure eating generally isn’t a major concern in healthy adult horses, steps should be taken to minimize this unsanitary habit:

• Correct nutritional deficiencies: Analyze the diet, calculate requirements based on workload and life stage, and adjust feed to provide adequate protein, vitamins and minerals.

• Supply ample forage: Grass, hay and other roughage should make up the bulk of the horse’s diet. Small, frequent forage meals prevent hunger.

• Add probiotics/prebiotics: Supplying probiotics or prebiotics helps maintain a healthy hindgut microbiome.

• Reduce grain intake: Limiting starchy concentrates prevents disruption of the intestinal microflora.

• Deworm regularly: Routine fecal exams and deworming keeps parasite numbers low to avoid gut microbiome imbalance.

• Increase exercise/turnout: Allowing horses to graze and socialize minimizes boredom and stereotypies like coprophagia.

• Provide toys/slow-feed nets: Hay nets, lickable treats and equine toys give stabled horses an outlet for natural grazing behaviors.

While coprophagia may look strange to us, it is rooted in the natural behaviors and physiology of horses. By making a few simple management changes tailored to the individual, horse owners can curb manure eating and support the wellbeing of their equine companions.