Why Does a Horse Eat Manure?

Eating manure, also known as coprophagia, is a relatively common behavior in horses that often leaves owners puzzled and concerned. However, there are several potential reasons why an adult horse may consume feces. By understanding the possible causes, horse owners can take steps to discourage this habit and support their horse’s health and wellbeing.

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

One of the most common reasons mature horses eat manure is to obtain missing nutrients from their diet. Manure contains undigested fiber, proteins, vitamins and minerals that passed through the digestive system. A horse with nutritional deficiencies may turn to coprophagia in an effort to recapture vital nutrients excreted in the feces.

Specific nutrient deficiencies that could drive manure eating include:

• Fiber Horses need a minimum of 1-2% of their body weight in forage daily. Insufficient roughage leads to hunger and the desire to seek out additional sources of fiber

• 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. Disruption from their normal schedule coupled with confinement and inadequate exercise often leads to boredom. Bored horses are at risk of developing repetitive behaviors called stereotypies, which includes coprophagia. Stabled horses with limited turnout are more likely to eat manure out of boredom and frustration.

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.

Horse owners have several options for managing manure, with composting and land application being the most common. Composting involves creating a pile of manure and bedding, turning it regularly, and monitoring temperature to break down the organic material, creating a nutrient-rich soil amendment. Alternatively, manure can be spread directly on fields or pastures as fertilizer, but careful management is needed to avoid over-fertilization or parasite proliferation.