Stomachs can be home to a host of worms and diseases

Health problems related to the digestive system in horses can range from dramatic to subtle and from mild to serious. Here are the top five digestive system disorders every horse owner should know:

The fear-inducing term colic applies broadly to abdominal pain.

Many intestinal problems can lead to colic, including twists, misplacements and blockages.

Colicky horses may kick or look at their belly, stop eating or defecating, roll or even dog-sit. Veterinarians diagnose the type of colic by doing a physical examination and a rectal palpation, listening to gut sounds and passing a stomach tube.

Treatment is based on the type of colic and can range from medical management, which is typically pain medication and mineral oil, to surgical correction of displacements and twists.

Many potential causes give rise to the different types of colic. For instance, impaction colic can occur when horses are fed dry hay with inadequate access to water. Their large bowel contents become too dry to pass.

Worms make their homes inside horses nearly everywhere from the mouth to the tail.

Although bot fly larvae migrate around the mouth before attaching to the stomach, most horse worms live in the large bowel.

One worm, Strongylus vulgaris, affects the bowel indirectly. Larvae of this worm live in a main blood vessel that branches off from the aorta and provides blood supply to a portion of the bowel. These worms cause inflammation and blood clots.

In severe cases, these clots travel down the vessel and block blood supply to the bowel, causing the tissue to die.

Pinworms make their home just inside the anus and deposit eggs around the tail head. Horses with pinworms may scratch their tails incessantly.

Stressed horses can develop stomach ulcers, just like stressed people. Sick foals and performance horses are most often affected.

The lower stomach normally produces acidic secretions to aid in digestion.

Contact between this acid and the upper stomach during high intensity exercise can lead to ulcers. Acid kills the outer layer of the stomach and it sloughs off, leaving a defect.

Clinical signs can be vague and non-specific, including decreased appetite, weight loss, colic and cranky attitudes. Affected foals sometimes grind their teeth.

Vets diagnose ulcers by passing an endoscope (a thin tube with a camera) into the stomach to examine the lining for ulcers.

Medication to reduce stomach acidity is commonly used to treat ulcers.

For some reason, horses are prone to biting off more than they can chew. Choke results when feed material lodges in the esophagus.

Horses fed course roughage may be prone to choke, especially if they have poor teeth. Also, dry hay cubes can easily get stuck.

Horses may continue to eat even though food can’t go past the stuck item. As the feed backs up, it can come out the nose as a green, slimy discharge.

Serious complications from choke include aspiration pneumonia, which is when feed material is inhaled into the lungs, and restriction, which is what happens if the lodged material isn’t removed promptly.

Veterinarians treat choke by passing a stomach tube or endoscope to flush with water and apply gentle pressure to whatever is stuck.

Horses are prone to developing sharp points and other dental problems because we tend to keep them in different conditions than what their wild ancestors experienced.

Wild horses evolved to graze on poor quality grasses for most of the day, but many domestic horses are fed infrequent meals of high quality hay and grain. This lack of continual eating is one factor that contributes to sharp point formation.

These points reduce the chewing surface, gouge the inner cheeks and trigger behaviorial problems because of pain.

A veterinarian should examine a horse’s teeth at least once a year. A “float” to remove sharp points and other corrective care can be done as needed.

Colic and choke are dramatic emergencies requiring immediate intervention. The others are more insidious, resulting in subtle, non-specific signs such as poor performance, weight loss and overall ill thrift.

If your horse isn’t quite right, it might be time to have a veterinarian give it a once-over to identify underling disease, including those of the digestive system.

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