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| A Horse Owner's Guide to the Equine Digestive System |
The horse's digestive system is complex and fascinating. As hindgut fermenters, horses rely on microbial fermentation to break down plant matter that their own digestive enzymes cannot. Join us as we journey through the equine digestive tract to better understand how our horses turn grass and hay into the energy and nutrients they need.
Biting, Chewing, and the Importance of Dental Care
A horse's day starts by grabbing mouthfuls of grass or hay with their front incisors. These front teeth act like scissors, neatly clipping blades of grass. Powerful tongue muscles then shift the food back to the grinding molars to be chewed.
Watch your horse eat and you may notice a pronounced side-to-side motion as they chew. This allows the ridged surfaces of their molars to thoroughly grind tough fiber. Over time, sharp points and uneven wear can develop on the molars. These abnormalities cause oral pain and difficulty chewing.
That's why regular dental floating by your vet is so important. Also called "filing", floating smoothes sharp enamel points and ensures even contact between the upper and lower arcades of teeth. Proper chewing is critical for good digestion and prevents painful dental issues.
Through the Esophagus and Into the Stomach
After being ground by the molars, food passes down the esophagus towards the stomach. The esophagus is a muscular tube connecting the throat to the stomach.
Sometimes dry feed will get stuck here, which is known as choke. Despite the scary name, choke has nothing to do with a horse's breathing. They simply cannot swallow the obstructing mass of food.
Horses with choke may drool, play in their water bucket without drinking, or act anxious. Choke is an emergency requiring immediate veterinary care. With prompt treatment, the blockage can usually be cleared before lasting harm is done.
Finally, the chewed food enters the surprisingly small stomach. Specialized glands here secrete hydrochloric acid, beginning the breakdown of nutrients. Unfortunately, the acidic environment also frequently causes painful gastric ulcers in performance horses and those on inappropriate feeding programs.
Ulcers lead to poor appetite, attitude changes, decreased performance, and colic. Your vet can diagnose ulcers via gastroscopy and can suggest targeted treatment plans involving medication, management changes, and dietary alterations.
The stomach is also where bot flies can wreak havoc. These flies lay eggs on horses' legs which are then ingested through licking and scratching. The larvae attach and develop in the stomach lining before passing out in the manure. Dewormers prevent bot infestations, so proper parasite control is essential.
Absorbing Nutrients in the Small Intestine
After a brief stay in the stomach, partially digested food moves into the small intestine. At an impressive 60-70 feet long in adult horses, the majority of protein, fat, and some carbohydrate digestion occurs here.
This is also where absorption of key nutrients takes place, so intestinal health is critical. Unfortunately, the environment here also suits a variety of parasites like roundworms and strongyles. Heavy parasitic infection can damage the intestinal lining and impair absorption.
This leads to weight loss, poor coat quality, and diarrhea despite a good appetite. Regular deworming and fecal testing helps detect and control parasites before they cause extensive damage.
Fermenting Fiber in the Hindgut
Now we exit the small intestine and enter the realm of the hindgut. This maze of organs houses trillions of microbial helpers that horses rely on to break down fibrous feeds.
Our first hindgut destination is the cecum. This large pouch is located on the lower right side of the belly near the flank. Recently swallowed food enters and mixes with special microbes that live there.
Powerful fermentation processes now break down fiber that cannot be digested by the horse alone. This microbial teamwork allows horses to unlock nutrients in grass and hay that would otherwise be unavailable.
After hours of fermentation in the cecum, the resulting slurry passes into the large colon where digestion continues. The large colon has several distinct sections.
First comes the ventral colon tracking along the bottom of the belly from right to left side. Near the pelvis, the food makes a sharp turn straight upwards into the dorsal colon. This tight bend is a common site for painful impaction colic. Food and fiber can get "stuck", causing life-threatening blockages.
Vets check for gut sounds and perform rectal exams to diagnose impactions. Large colon impactions are treated with laxatives, pain control, and possibly IV fluids. Preventing dehydration and offering a high quality, balanced diet can help minimize impaction risk.
Traveling forward again, material passes through the short transverse colon before entering the final fermentation chamber known as the small colon. Here, remaining nutrients are absorbed while muscular bands shape the waste into dry manure balls for passing.
Finally, digested material enters the rectum for expulsion as manure, completing an astounding journey that allows horses to thrive on high fiber diets.
Supporting Digestive Health
Given the horse’s complicated digestive tract, issues are bound to crop up. Let’s explore some common health concerns and tips to optimize digestion.
Dental Care
Regular dental exams and floating help prevent uneven wear, sharp points, and periodontal disease. Catching dental issues early keeps your horse comfortable and ensures proper chewing.
Tip: Schedule dental appointments every 6-12 months based on your horse's needs. Addressing problems before they get bad saves teeth and lets your horse eat happily.
Ulcers
Ulcers are unfortunately very common in modern management systems. Stress, intermittent feeding patterns, non-forage diets, and intense exercise all increase ulcer risk.
Tip: Allow free-choice hay feeding and consider supplemental alfalfa. Ask your vet about omeprazole if ulcers develop.
Parasites
Don’t let parasite numbers get out of hand. Consult your vet to develop a targeted deworming plan based on your horse’s age and exposure risk using fecal testing.
Tip: Pick paddocks carefully and remove manure frequently to reduce parasite contamination. Rotate dewormer classes yearly.
Impaction Colic
Impactions cause immense pain and require rapid treatment. Support good gut motility and hydration to keep things moving.
Tip: Feed at least 1.5% of your horse's body weight in hay daily, provide salt blocks, and monitor water intake. Address health issues early.
Nutrient Absorption
Disorders reducing small intestinal absorption will result in weight loss and diarrhea despite a good appetite. Catch malabsorption early through routine physical exams and weight tapes. Identify and treat the underlying cause, whether that is parasites, systemic illness, or gastrointestinal disease.
Tip: Weigh monthly, learn your horse's healthy weight, and inform your vet of any changes. This facilitates early diagnosis of many digestive and systemic diseases.
Support Your Horse's Digestive Health
The equine digestive tract is a complex system adapted to high roughage diets. Support your horse by providing abundant hay, fresh clean water, routine parasite control, and regular veterinary care. Get to know what is normal for YOUR horse and inform your vet quickly when issues arise. Here's to many happy grazing years together!