The Anatomy Behind Colic
The equine digestive tract consists of two parts. The foregut consists of the stomach and small intestine. The hindgut or large intestine includes the cecum and colon. After being partially digested in the stomach and small intestine, food ferments in the cecum.
Pro Tip: Contact your veterinarian immediately if you believe your horse is experiencing colic symptoms.
Types of Colic
Physical blockages or narrowed parts of the GI tract may prevent fluid and digested material from continuing throughout the rest of the GI tract. These are non-strangulating obstructions.
ImpactionsImpactions commonly occur in the pelvic flexure in the large colon and the bend to the transverse colon. The narrow turns cause feed, sand, fibers, or a combination to get stuck in these areas creating a blockage. Horses who drink less water in the winter or after a recent surgery may be more susceptible to impaction.
The risk of impactions may be lowered by monitoring feed quality and preventing sudden feed changes. Access to fresh water, a regular deworming schedule, and regular dental checks aid in the prevention of impactions.
EnterolithsWhen a foreign object enters the intestinal tract, stones formed by deposited mineralized salts are known as enteroliths. When there are two or more in the same space, they can rub together and create an even bigger problem. Obstructions generally occur in the right dorsal colon, transverse colon, or small colon where the GI tract is narrower. As the obstruction grows, it acts as a valve before closing off the bowel completely once it is large enough.
Displacement of the Large ColonThe large colon moves freely in the horse’s abdomen and, as a result, can be displaced from its original position. The colon can become partially entrapped, twisted, or pinched off. Signs of an “uncomplicated” displacement include intermittent bloating, loss of appetite, and mild to moderate signs of colic.
Strangulating ObstructionsWhen the blood supply of the intestinal wall is restricted, this results in a strangulation obstruction. A horse with a strangulating obstruction will deteriorate quickly and requires immediate veterinary intervention. Common signs in addition to normal colic signs are rolling from side to side, lying on their back, and excessive sweating.
VolvulusThe horse’s intestine can twist, resulting in a volvulus. This twist shuts off the blood supply, and normal digestion can not continue. Volvulus can occur in the small intestine due to adhesions, worm impactions, and lack of normal contractions of the gut. The large colon can also be affected due to its size and loosely attached to other parts of the digestive tract.
Young horses are commonly susceptible to their small intestine telescoping into an adjacent segment of the bowel. It occurs due to inflammation, worm infestation, or dietary changes that result in abnormal peristalsis. Depending on the location of the intussusception, the symptoms will appear abruptly or gradually. If the obstruction is not complete when symptoms start, it may appear as a spasmodic colic.
Inflammatory conditionsAny inflammatory disease of the small intestines is known as enteritis. Most cases involve the colon and diarrhea is the main symptom so the name has evolved to enterocolitis. Infectious diseases are the most common cause, but intestinal parasites can cause this as well.
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