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”. When 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.
As from yesterday one of our geriatrics horses, Saeta, is, sadly, suffering from enteritis. Of the enteritis there is two types, the anterior and the proximal. Enteritis means an inflammation of the small intestine.
The cause is not always known, but bacterial overgrowth, viruses or parasites may be to blame. In general, studies have failed to show a root cause – each case can have a different reason for developing inflammation. That can make it very difficult to figure out how to prevent it. Regardless of cause, however, the effects of this disease can be devastating.
To understand what happens in this disease, you first must understand the normal function of the small intestine. The small intestine is about 80 feet of a narrow, flexible tube which connects the stomach to the cecum (the first part of the large intestine, where fermentation begins). The small intestine is responsible for absorption of nutrients, including proteins, simple carbohydrates, fats and vitamins. To do this, the inside of the small intestine is covered in lots of projections, which increase the surface area. When the small intestine becomes inflamed, absorption stops. Instead, fluid starts entering the small intestine. The small intestine becomes distended with fluid. The significant distension inhibits contractions which would normally cause the fluid to enter the large intestine; instead, fluid backs up into the stomach. Since horses cannot vomit, fluid entering the stomach has nowhere else to go. If a tube is not placed by a veterinarian, the stomach can actually rupture.
It is not uncommon to obtain 10-20 L of fluid off of a horse’s stomach that is suffering from this disease. As we said, if the fluid is not removed, the stomach could rupture – which, as you can imagine, is usually fatal.
Since a horse with anterior enteritis is dumping so much fluid into the small intestine and stomach, they can become dehydrated very quickly. These fluids have to be replaced via intravenous fluids. Other treatments include anti-inflammatory medication (usually Banamine) and anti-endotoxic drugs such as polymixin B. Motility agents such as lidocaine or metoclopramide are also employed many times to couteract the effects of distended intestine. Antibiotics are not always necessary, however if the cause of the disease is suspected to be bacterial, or secondary bacterial infections are found, then they may be added.
If all we had to worry about with anterior enteritis was fluid removal from the stomach, and intravenous fluid replacement to maintain hydration, we would still have a lot on our hands. Unfortunately, that’s not all we have to worry about. When the gut becomes compromised, bacteria and toxins are free to enter the bloodstream and basically run amok among the horse’s internal organ systems. These elements can cause many complications alongside the already difficult to treat enteritis. One of the more common sequelae of anterior enteritis is laminitis.
If treatment is instituted early, complications may be limited, but as we said earlier, this can be a devastisisng disease, especially when our patient is 27 years old.
This article is to you Saeta, and fingers crossed you will be with us for, at least, a few years more.