Impaction Colics

By: Katie Jones, CVT

Colic. This word alone makes most horse owners cringe with just the thought of it. It is a moment horse owners hope to never face with their four-legged friends. The term “colic” is actually a very vague term that refers to any abdominal pain a horse is experiencing. Colic is predominantly used to describe pain caused by the gastrointestinal tract, but other abnormalities may cause a horse to exhibit colic like symptoms. With the weather changes winter can bring, horses can be at an increased risk for impaction colic.

Anatomy

ImpactionThe gastrointestinal tract of the horse is about 100 feet long with most of it consisting of the intestines. Food initially enters the mouth and travels down the esophagus and into the stomach. Horses do not have reverse peristalsis; meaning, food can only travel in one direction and they can not vomit.   In contrast to other grazing animals, horses are a monogastric species only having one compartment to their stomach which is divided into squamous and non-squamous portions. Once the food leaves the stomach, it enters into the small intestines (50-70 feet long) through the pylorus where most of the digestion and nutrients are absorbed into the bloodstream. Any remaining liquids and roughage is then moved into the large intestine.

The first part of the large intestine is the cecum (4 feet long), which is a blind sac. This area of the intestine has bacteria that digest plant fiber through fermentation, making the horse a “hind-gut fermenter.” The reason horses need to have their diets changed slowly is to allow the bacteria in this region of the gut to modify and adapt to the different chemical structures of the new feedstuff. After the cecum, feed enters the colon. Although the colon is a much shorter structure then the small intestine at around 20 feet, this area of the GI tract undergoes abrupt changes in direction and decreases in the lumen diameter; all of which causes it to be a common place for impactions.

An impaction is a formed blockage of feed stuff or other materials in the intestines. Although an impaction can occur anywhere within the intestines, there are several sites were they are seen more commonly.

Pelvic Flexure Impaction

The pelvic flexure is a portion of the large colon that normally sits in the left side of the impaction1abdomen near the left flank. This area is a common place for impactions to develop due the lumen diameter decreasing rapidly and the abrupt direction change. This form of impaction will cause a horse’s fecal output to decrease, if not stop. Pelvic flexure impactions are diagnosed via rectal palpation. Treatment will consist of a veterinarian placing a nasogastric tube down the horse’s esophagus and administering mineral oil mixed with water. The goal is to provide fluid to soften the impacted feed material. If the horse does not respond to the oral fluid treatment, the horse may need to be given fluids intravenously. Pelvic flexure impactions that do not respond to medical treatments or their pain level gets too high will eventually require surgery.

Cecal Impactions

Due to the cecum being a blind-sac, feed material enters and exits through the same end; predisposing impaction problems in this area. Cecal impactions are diagnosed by feeling a mass on the right side of the abdomen during a rectal palpation. The early treatment plan is similar to a pelvic flexure impaction (oral and IV fluids), but distention of the cecum can lead to rupture quickly often making surgical intervention a necessity to prevent rupture.

Small Colon Impaction

Small colon impactions are most commonly caused by fecal material (fecolith) after diarrhea episodes or meconium in foals. Miniature horses are predisposed to small colon impactions. Diagnosis can occasionally be done by rectal palpation; however, in cases where the area can not physically be reached, a diagnosis is made based on clinical signs. When a small colon impaction is secondary to diarrhea, the horse may exhibit a fever, a low white blood cell count, or numerous other clinic signs associated with endotoxemia (the presence of endotoxins in the blood). When the horse is systemically compromised, treatment starts similar to other impactions, but will also be treated with antibiotics, anti-inflammitories, and/or anti-endotoxic medications. Horses with small colon impactions may respond to medical treatment, but often require surgery if they continue to display colic-like symptoms after treatment has been started.

Colic prevention quite honestly comes down to management practices. Regardless the time of the year, it is important to provide high quality roughage and ample clean water. During the winter months, providing water buckets free of ice and at a slightly warmer temperature will encourage horses to drink even in extremely cold weather. Intestinal contents have a high water content which produces a soupy consistency as it passes through the GI tract. Horses should consume around 10 gallons of water per day, even in very cold weather, to maintain this high moisture content. Annual dental examinations will not only prevent the development of dental issues, but they will also allow the horse to properly chew their forage; therefore decreasing the chance of an impaction colic. Having a close relationship with a veterinarian will help in formulating a feed and management program to prevent impactions.

SmartPak Colic Care : https://www.smartpakequine.com/ColiCare

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