Dr. Brian Eitelman, DVM, CJF, and Aggie Vet and Farrier Services provide veterinarian and farrier services in Parker, CO, Elizabeth, CO, Franktown, CO, Castle Rock, CO, Sedalia, CO and Larkspur, CO. To learn more, please visit us at www.vetandfarrier.com
In this episode, Dr. Brian explains what colic in horses is, goes over the different types of colic in horses, as well as times when horses are more at risk of colic.
The term colic in horses simply refers to pain anywhere in the abdomen. Most often this is related to the GI tract - the stomach and all the intestines both large and small. The GI tract is around 100ft long so there is no shortage of areas to have a problem. There can be a few other causes of abdominal pain like mares cramping at beginning of their heat cycle. However, for this video, we’ll just focus on the primary suspect in most cases - the digestive system.
There are any number of ways to categorize colics and this is just my system. The first is “too much going on or hyperactive.” One common version of this is often called gas colic - excess gas that swells or bloats the intestines and can be really painful. The other common culprit in this category is “spasmodic” - think cramping or diarrhea. The intestines are hyperactive and those spasms can be really painful.
The second category of colic is basically the opposite of the first type and it is called ileus. This term is used to describe any part of the intestine that isn’t contracting and moving stuff along, it’s just sitting there. There’s nothing blocking it or choking it off. You don’t usually know what turned that part of the intestines off and there’s usually no way for US to turn it back on. So, a lot of the time these horses end up at hospitals for intensive care and monitoring.
The third category that I use for colic is impaction - a traffic jam inside the tube. Most often, it is caused by a wad or clump of feed but occasionally can be caused by hay string, parasites, or even intestinal stones. Dehydration plays an important role in this condition. Cut hay whether grass or alfalfa has very low water content compared to fresh grass. This means that a horse needs to drink a lot of water to help move the feed along. Each intestinal wave that contracts and moves food along is also squeezing moisture out of it like wringing out a towel. Now, this isn’t a problem if the horse is drinking properly because they’re regularly chasing food with water. A problem arises if a horse 1) starts from a point of dehydration like a hungry horse after a long sweaty ride, 2) when they’re more motivated to eat than to drink like a horse who’s cold, or 3) a horse who stops drinking completely like a horse experiencing a relatively mild colic. The food that is already in there is still getting wrung out but with no more water coming down, it gets too dry and tends to jam up.
Additionally, there are some natural choke points that tend to exacerbate this problem. There are several places where the diameter of the intestines goes from 6-8 inches down to 2 inches with a tight turn. This is fine for horses grazing small meals of wet fresh grass all day but causes problems when we feed them large meals of dry hay. Because of the necessity of water intake to properly move feed along, it is very common for a horse with a minor colic to become dehydrated and then develop a life-threatening obstruction. To make matters worse, the longer that obstruction sits there, the more it is damaging the part of the intestines where it is stuck AND with each successive wave trying to move it along, it gets drier and drier.
The final category of colic is one of the scariest and almost always requires surgery. This is where the intestine itself moves into the wrong area or displaces, the intestine itself twists part or all the way around, or something squeezes off the intestines from the outside - commonly this is a tumor that tends to grow on a stalk and eventually gets thrown over the intestine and clamps it off like a tether ball around a pole. A horse with intestines in one of these conditions tends to be extremely painful, gets little if any relief from pain meds and sedation, and overall gets very bad very fast and it is basically a transfer to surgery or euthanize situation.
There are a lot of times we won’t know what caused a colic but there are some situations that have a higher risk of colic like a sudden change in diet or in the weather. A sudden change in diet is notorious for causing excess gas, cramping, and diarrhea as the microbes adjust to the new type of feed. Also, when there is a rapid drop in the temperature or access only to excessively cold water, horses aren’t as interested in drinking. We like to make this problem worse by feeding them extra hay in a nice warm barn but the water is outside in the cold. So again, we see that combination of eating but not drinking enough causing a problem.