In our last post, we discussed (mainly) non-surgical types of large intestinal colic. However, as we all know, sometimes colic goes beyond what we can treat in the field and referral for surgery is necessary. Typically, these result from the colon moving (or displacing) into a place that it shouldn't be. That being said, some of these can be treated medically, however not always successfully. Since we've already gone over the anatomy of the large colon, (See Large Intestinal Colic: Part One) let's jump right into what might have happened if your horse's bowel becomes blocked.
Right Dorsal Displacement: The left colon is quite mobile and likes to get stuck in places. In a right dorsal displacement (RDD), the left colon slides around to the right side of the abdomen and gets stuck between the cecum and the body wall. The pelvic flexure (the U-shaped area at the top of the picture) moves from the back end of the abdomen (near the rectum) to end up near the diaphragm. This is all kinds of crazy! The large intestine becomes partially occluded and gas distended. In practice, we can see this occur in conjunction with a pelvic flexure impaction. Generally speaking, the blood supply remains intact so the bowel remains healthy. We can sometimes treat these with fluids and withholding feed, but often times surgery is required. At surgery, the colon just needs to be decompressed and repositioned into the appropriate anatomic location. As long as nothing more serious is going on, these horses recover quite well.
Previously, we have discussed small intestinal colic and gastric ulcers. However, when discussing colic, we have to determine if it is small intestinal in origin or large intestinal.
Below is a brief list of problems associated with the large colon. Typically, these are non-surgical and can be resolved with some medical management. That's not ALWAYS the case, but for the most part it is. (Part 2 will focus on more severe types of large intestinal colic.)
Colic is a scary word to horse owners and veterinarians. However, some types of colic are much worse than other types. While 90% of colic cases resolve with minimal treatment on the farm, some require more intensive care. One such type of more serious colic is small intestinal strangulation, which is an obstruction of the blood supply and the lumen (the inside of the tube, where food passes through) of the small intestine.
The horse's gastrointestinal system is quite lengthy - it spans approximately 120 feet, and the majority (70-80 feet) of that is small intestine. Furthermore, it's mostly floating freely in the abdomen, with minimal attachments to the body wall and surrounding organs. This conformation gives lots of opportunities for something to go wrong, whether that's a twist, or some other way that the intestine ends up in the wrong spot.
The small intestine (or SI, for short) is the same in horses as it is in dogs, cats or humans. It's made up of 3 segments - the duodenum, the jejunum and the ileum. The duodenum is the first section, just after it leaves the stomach and for about the next 12-16 inches (that's it - so, not much goes wrong with the duodenum!) The jejunum makes up the bulk of the small intestine, and the ileum comprises the last foot or so before it enters the cecum. There are minor variations in these structures, but we don't have to worry about them here. All this SI is suspended within the abdomen by a sheet of connective tissue called "mesentery". (If you laid a garden hose straight across a towel, then picked the towel up at all 4 corners it would create the same effect.) The mesentery brings blood supply to the intestines.
The equine digestive tract is always a concern for horse owners - and veterinarians! Colic can be caused by many different things, and one possibility is EGUS - Equine Gastric Ulcer Syndrome. Gastric ulcers are actually quite common in horses. There are a variety of reasons for this, but have no fear! While they are common, they are rarely life-threatening and can be cured with appropriate treatment.
First, let's start with an anatomy overview. The equine stomach is divided into two sections - the non-glandular (or squamous) section, and the glandular area. The line dividing these areas is known as the "margo plicatus". Stomach acid is secreted by the glandular area. We typically see ulcers along the margo plicatus on the squamous side of the stomach, but we can also see ulcers throughout the non-glandular and glandular regions. Oh yeah, and just to be clear, gastric ulcers are erosions in the normal lining of the stomach. Pretty simple so far, right?
There is a lot that can go wrong inside a horse's abdomen. When something does go wrong, and we start seeing symptoms, we refer to it as "colic". If you've worked around horses for long enough, you've seen the signs - inappetance, pawing at the ground, lifting the upper lip, rolling... it can be pretty scary. Colic just means "abdminal pain", however most often we use it to refer to a problem with the gastrointestinal tract. The horse's intestinal tract, like ours, is made up of the stomach, small intestine, and large intestine. In this blog post, we are going to discuss a specific disorder that affects the small intestine - "anterior enteritis". This is a complex disorder, which can be confusing - we'll try our best to keep things as simple and clear as possible, and try to make sense of this dangerous disease.
Drs. Ashley and Matt Kornatowski share their experiences and insights into veterinary medicine. We hope you find this blog both informative and entertaining.