As Spring begins to peak around the corner here in Canada, now is the perfect time to have a conversation about Colic, as the change in Season often brings an increase in the prevalence of this condition.
In this article you will learn about the horses digestive system, different types of colic, the most common triggers and the best practices to follow in order to lower your horse's risks of colicing for years to come. Many of the talking points I will be highlighting come from an in-depth conversation and seminar session I had the privilege of attending with leading experts in the field of equine nutrition and veterinary science (Dr. Andy Durham). Sam PotterHorses are known as monogastric animals based on how their gastrointestinal tract is structured. A monogastric animal is one that has a “simple” stomach also known as a stomach with a single compartment (HarperCollins). Furthermore, horses are hindgut fermenters which means they digest cellulose mainly through the cecum and colon.
A horse's digestive system can be broken down into 4 main compartments:
A. Mouth
- Lips are used to grab food and teeth grind it down
- Chewing and saliva soften/breakdown the food
- Morsels are swallowed into the esophagus which uses peristalsis waves to move it down to the stomach
B. Stomach
- Digestive juices are secreted by the stomach lining
- Protein is broken down further into simple amino acids and minerals are dissolved
- Ingesta travels from stomach to the small intestine
C. Small Intestine
- Most nutrients are absorbed here and are transported into the lymphatic system and carried around the body
D. Hindgut
- Cecum then breaks downs the fibre and soluble carbs as well as synthesize Vitamin B’s
- Ingesta then moves to the large colon where more bacterial fermentation occurs and more moisture is absorbed into the body
- More water is absorbed from ingesta in the small colon and leaves mostly solid waste behind
- The rectum holds the waste material until it is passed through
There is a variety of colic forms but as a whole, colic is described as a disorder of the intestine resulting in abdominal/intestinal pain. It affects approximately 5 out of 100 horses colic each year. Before I get into the specific forms of Colic I will share the signs to watch for and use to distinguish if they are experiencing it. These signs will range from least to most severe.
Colic signs:
MILD
- Inappetence
- Grimacing/lip-curling
- Exaggerated or more frequent yawning
- Flank watching and stretching as if need to pee
- Laying down excessively
MODERATE
- Kicking at abdomen
- Intermittent scraping
- Excessive pacing
- Sweating
SEVERE
- Persistent scraping
- Buckling and threatening to lay down
- Recumbency
- Rolling
7 forms of Colic
Spasmodic: Spasms or cramping of intestinal segments
Gas: Gas build up within intestinal loops. Can progress into displacement
Impaction: Blockage from feed within the intestine
Enterolith: A stone that forms in the intestine causing blockage. Associated with Alfalfa hay
Displacement: When a loop of intestine moves into an abnormal position
Torsion: When a section of the intestine wraps around itself
Strangulation: A section of intestine is constricted from getting trapped between 2 structures or by something wrapping around it.
Known Colic Triggers
Colic is one of the most common conditions among horses and can be caused by various factors. Some of the established triggers for colic in horses include parasites such as roundworm and ringworm, feed practices, lack of water access, diet, increased exercise, stabling or lack of pasture access, transport due to stress and limited food access, general anesthesia, and weather. Parasites can cause blockages in the intestinal tract, leading to colic. Poor feed practices can result in changes in gut flora, leading to digestive issues. Lack of water access can cause dehydration, which can also lead to colic. Diet changes can also be a trigger, especially when introducing new feeds. Increased exercise can cause digestive upset, while stabling or lack of pasture access can lead to reduced motility and an increased risk of colic. Stress during transport can also contribute to colic, as can general anesthesia.
Triggers of Focus: Season, Grain and Motility
The most common reasons for colic in horses are related to their diet and environment. Horses have a delicate digestive system, and any rapid changes to their diet or too high of starch content can lead to digestive upset. More changeable weather conditions, particularly in the spring and fall season, can also be a major trigger. As demonstrated in the graph below, horses have the highest peak in colic incidences during May overall and another smaller peak during October. Based on the data extrapolated, it actually shows that colic umbers increase at the end of April and very beginning of May based on the dates.
Colic occurrence being more prevalent during mid-spring and mid-fall is likely related to rapid changes in diet due to changing forage nutrient contents. Abrupt changes in a horse's diet can upset the balance of the horse's digestive system. This is why it is always recommended that new feed or forage are introduced gradually. It is important to make any changes to a horse's diet gradually over 14 days or even 21 days to allow their digestive system to adjust. Additionally, feeding a diet that is imbalanced or lacking in essential nutrients can increase a horse's probability of colic.
Unfortunately with such drastic weather changes forage nutrient contents, exercise and environment changes so rapidly it can be hard to manage it can increase colic prevalence, especially in areas (such as Canada) that have drastic seasonal changes in temperatures and feed type availability!
Horses require a specific balance of nutrients, including fibre, protein, vitamins, and minerals, in order to maintain proper digestive function. A diet that is too high in carbohydrates or too low in fibre can significantly increase the risk of colic. Therefore, it is crucial to provide horses with a balanced diet and make any changes to their diet is done slowly and carefully to help prevent colic. This will segue to our next trigger of focus, grain.
As evidenced by the graphed data above, feeding more than 2.5 kg of grain per day can increase the risk of colic by 3-6 times! This is likely due to the fact that grain is less easily absorbed in the horse's gastrointestinal tract and produces a greater amount of gas due to its high fermentability in the large intestine. When horses consume too much grain, it can cause an overproduction of lactic acid in the gut, leading to a pH imbalance disrupting the delicate microbial balance in the gut. This can result in inflammation and irritation in the intestinal lining, leading to discomfort. By providing a balanced diet that includes adequate forage and limiting high-grain feeds, it can help promote optimal health and decrease your horse's colic risk.
Additionally, if horses do not have access to fresh, clean water while consuming high levels of grain, it can dramatically increase a horse's risk of colic, more specifically impaction colic due to the dryness and density of the feed. This form of colic is when a blockage occurs in the intestine. These are some reasons why monitoring a horse's grain intake and ensuring that they always have free access to fresh water will help prevent medical complications.
Research has shown that horses who are stabled are at a 30X higher risk of developing colic than pastured horses. This is likely due to depressed motility and prolonged periods of without much movement. Horses have evolved as grazing animals that travel long distances in search of food and water. In the wild, horses spend the majority of their time moving around and grazing with their herds. This has resulted in their digestive system adapting to their habits. Their system functions best when they are moving around, as movement aids the muscular contractions move food and waste through their gastrointestinal tract. When motility is lowered, the passage of food and waste slows, which can lead to the accumulation of gas and fluid in the intestine. Stabling a horse for prolonged periods of time can impact its evolutionary behaviours, which is why it can lead to significantly higher risks of colic.
By providing consistent opportunities for exercise (more than just training) and turnout you can reduce your horse's risk and help maintain not only their digestive health but their overall well-being.
Summary
The takeaway message from this article is to ensure a horse's diet is consistent and their grain intake is no more than 2.5kg per day; additionally, providing motility and access to pasture can help prevent colic. Something to also be aware of is how seasonal shifts can affect your horse's risk of colic. Monitoring your horses more closely during these periods can help identify signs of colic earlier and prevent more severe cases.
References
Done in Veterinary Journal format
Auwerda, P., n.d. Digestive anatomy and physiology of the horse [WWW Document]. Equine Science. URL https://www.extension.iastate.edu/equine/blog/dr-peggy-m-auwerda/digestive-anatomy-and-physiology-horse (accessed 3.20.23).
Diakakis, N., Tyrnenopoulou, P., 2018. Correlation between equine colic and weather changes [WWW Document]. Research Gate. URL https://www.researchgate.net/publication/322874074_Correlation_between_equine_colic_and_weather_changes (accessed 3.19.23).
Durham, A., Potter, S., Walsh, T., 2023. Reduce the Risk of Colic. Colic Masterclass.
HarperCollins, n.d. Monogastric definition and meaning: Collins english dictionary [WWW Document]. Monogastric definition and meaning | Collins English Dictionary. URL https://www.collinsdictionary.com/dictionary/english/monogastric (accessed 3.17.23).
Nathaniel, W.A., 2005. Prevalence, demographics, and risk factors for colic - researchgate [WWW Document]. Research Gate. URL https://www.researchgate.net/profile/Nathaniel-White-4/publication/237440828_Prevalence_Demographics_and_Risk_Factors_for_Colic/links/00b7d53c8fcd811a7f000000/Prevalence-Demographics-and-Risk-Factors-for-Colic.pdf (accessed 3.21.23).
Salem, S., Scantlebury, C., Ezzat, E., Abdelaal, A., Archer, D., 1970. [PDF] colic in a working horse population in Egypt: Prevalence and risk factors: Semantic scholar [WWW Document]. Equine Veterinary Journal. URL https://www.semanticscholar.org/paper/Colic-in-a-working-horse-population-in-Egypt%3A-and-Salem-Scantlebury/2360c97534151cfd5cccc17cc5a55b284c5d0852 (accessed 4.15.23).