Colic in Horses

For most horse owners, the number one fear for their horses is colic. To reduce colic, we must first understand its contributing factors. In this post, we'll explore this very important topic further.

Humans Are Often the Problem

Sadly, many factors that cause colic are attributable to our mismanagement of horses.

Horses evolved in Asia and the Middle East in an arid environment. They were designed to be foragers as they are a hindgut herbivore. Due to their evolution in this environment, horses were forced to forage large areas (up to 20 miles per day) in order to get enough to eat. Horses have a small stomach only representing 7% of their digestive tract. Therefore they need to graze almost continuously. They selectively graze the plants that are the most nutritious. On occasion they would eat grass seeds but never in great quantity.

As man domesticated the species, confinement was implemented and the horse’s whole way of life changed. Parasites also became a problem because of confinement to small areas. Feeding horses at man’s convenience led to a change from a continuous forager to a meal eater, whereby the majority of the dietary energy is derived from grains. Most of the time, colic is due to feeding mismanagement resulting from a poor understanding of the horse’s digestive tract.

Colic Risk Factors

Texas A&M University Animal Science Department, in conjunction with the Texas A&M Veterinary College, did a very meaningful research project that illustrated the risk factors that were associated with colic. They found:

• Colic increased as farm size decreased.
• Being stalled more than 50% of the time increased risk of colic.
• Horses that were outside drinking had less risk than horses that were stalled watering from a bucket.
• It didn't matter what the primary use of the horse was (breeding, racing etc.), but changes in activity were associated with colic.

The study also found no meaningful relationship between colic and the feeding of vitamin, mineral, protein, or fat supplements. However, a change in the type of hay offered has been shown to potentially lead to colic. Hay of poor quality is often less digestible, predisposing to impaction. Changing types of hay may be related to colonic pH changes resulting from calcium differences in the two hays.

An additive effect also seems to occur when changes in hay are stacked with other changes, such as changes in activity or changes in housing. But on the more positive side, horses with regular deworming programs were noticeably less likely to develop colic.

Preventing Colic

A good colic management program includes several key elements:

• Parasite control. A series of fecal exams to detect the presence of worms would give a baseline assessment of the parasite level in the herd. Based on these results, a deworming schedule should be set up accordingly. Choose an anthelmintic that is broad in spectrum and safe for the class of horses and the level of infection present. Being overly aggressive in the choice of “purge deworming” products can have disastrous results, and consulting with your veterinarian about his/her recommendations about the types of products available is wise.
  
  
• Regular dental care. A horse’s teeth grow 1/8 inch per year and need to be floated annually. Grinding of grain contributes to reduced particle size and allows for salivation, with amylase aiding in the digestive process. Hay needs to be chewed thoroughly in order help prevent impaction. Horses with dental pain often shortcut chewing.
  
  
• Grain or concentrate. Feed a grain or concentrate that minimizes starch content (low nonstructural carbohydrate – a starch measurement in feed) and includes other energy sources such as fat and digestible fiber. Always feed grains/concentrates at least twice daily, and never feed more than 0.5% of body weight at any one feeding. Processed feeds (pelleting, steam flaked, etc.) increase starch gelatinization, thereby increasing pre-cecal digestion. The increase in pre-cecal digestion reduces the risk of starch spilling into the cecum and colon, therefore lowering the risk of colic.
  
  
• Feed timing. Again, remember that horses are continuous eaters so meals should be evenly spaced. And if a meal is late, never feed more to make up for it. It is better to feed a little more hay and even reduce the amount of concentrate for that meal. Go back to normal feeding the next time.
  
  
• Hay / pasture. Horses experience colic less while on pasture. It allows them to graze continually and also provides exercise. Pastures are generally the best way to feed a horse, but variations in the weather throughout the year introduce challenges. For this reason, hay should also be available when grass runs short. Practice some form of pasture rotation, and keep in mind that lush, high-moisture pasture can contribute to colic, particularly when horses are first turned in. A slow introduction and a gradual increase in the time that horses are allowed on pasture is critical. It is also a good idea to feed hay to the horses before they are allowed on pasture. And as a general rule, hay should be fed at a minimum of 1% of body weight when horses are kept in confinement.
  
  
• Individual feeding. Feeding horses individually in stalls, pens, or by tying the horse up is an ideal situation. This way they can be fed according to body weight and condition without fear of competition. Competition can cause a horse to bolt its feed (rapid ingestion and swallowing), allowing a dominant horse to overeat.
  
  
• Dietary changes. Remember that we are feeding the “bugs” rather than the horse. In the colon and cecum, millions of bacteria and protozoa reside where they digest fiber for the benefit of the horse. It takes time for this microbial flora to adapt to a dietary change. Gradually increase the new feed mixed in with the old feed over a 7-10 day period.
  
  
• Water: Fresh clean water is imperative. Decreased water consumption will contribute to impaction in the colon and cecum. Water consumption is based on palatability, temperature, and availability. High solids, high mineral content and contamination are reasons that can lower intake. Horses will also lower their water consumption in the face of poor water quality, which may be caused by some forms of algae that are toxic.
  
  
• Exercise. Feeding should be at least 2 hours prior to or after exercise. Grain feeding should be withheld 8 hours prior to strenuous exercise; hay should be given in small portions in multiple feedings the day of the event. Water should be available free choice.
  
  
• Fast eaters. Horses that tend to bolt their feed (large bites with minimal chewing) should be fed in large bottom troughs where the feed can spread out.
  
  
• Happy horses. Minimize stress. Keep horses in small groups; keep the groups the same. Horses are gregarious (they like each other’s company). Once a pecking order is established, anxiety is created by moving them around. Anxiety can cause colic; this is what happens due to a change of housing. Some horses pair up and if they have to be separated, use sedation to minimize anxiety.

We realize, of course, that this is a LOT to take in all at once. But if you need advice or help regulating your horse's nutritional needs, be sure to call or stop by and chat with one of our knowledgeable associates. We'll be glad to take care of you!

NOTE: This content is adapted (with permission) from our partners at Nutrena and Cargill Animal Nutrition. The original article appears here.