Colic Is Rarely Random: The 7 Proven Risk Factors and What to Do About Them
What Research Says About Why Horses Colic and How to Lower the Odds
Key Takeaways
- Colic is the most common reason for emergency veterinary treatment in the horse¹
- A history of previous colic is one of the most consistently identified risk factors across multiple studies¹
- Recent changes in feed type or housing are among the strongest documented management-related risk factors for colic¹
- High concentrate diets and limited turnout are associated with significantly increased colic risk¹
- Horses with colic have measurably lower gut microbial diversity and higher levels of harmful bacteria compared to healthy horses²³
- Most colic risk factors come down to management decisions made every single day
- The gut microbiome is not just a byproduct of what horses eat — it is one of the most important factors in whether they colic or not
Quick Answer
Colic is rarely random. A comprehensive systematic review of the equine colic literature identified history of previous colic, recent feed changes, recent housing changes, high concentrate diets, limited turnout, dehydration, and poor parasite control as the most consistently documented risk factors.¹ Most of those factors are within your control. Understanding what actually drives colic risk and what you can change is the most effective protection your horse has.
You Know the Five Letter Word
It does not matter how long you have been around horses. The word colic stops you cold every time.
Every horse owner has felt it. That moment of watching a horse paw, look at its flank, or refuse to eat. The calculation starts immediately. Is it serious? Do I call the vet now? What did I do differently?
Here is what most people do not realize. The risk factors for colic — feeding practices, management changes, medical history, and parasite control — are well documented in the research literature.¹ Most of those factors are within your control. Colic is rarely a random event. It is most often the predictable result of a decision made, or not made, in the days before it happens.
Here is what the research actually says.
1. A History of Previous Colic
A history of previous colic is one of the most consistently identified risk factors across multiple studies, confirmed in the most comprehensive systematic review of equine colic risk factors published to date.¹
As Dr. Rob Franklin puts it, if you are waiting until you see the horse get cinchy, start to lose weight, or have loose manure, you are already way behind. If your horse has colicked before, that is not a reason to panic. It is a reason to be more deliberate about every other risk factor on this list. The management decisions that contributed to the first episode are almost certainly still in play if nothing has changed. The gut is trying to tell you something.
2. Sudden Changes in Hay
Recent changes in feed type are among the strongest documented management-related risk factors for colic in the systematic review literature.¹ Multiple studies confirm this association consistently.
Dr. Franklin explains why: "That's why your vet's always telling you to make feed changes very slowly." The hindgut is populated by a complex community of bacteria that have adapted to digest the specific forages your horse eats. When the hay changes, even from one cutting to the next, those microbes need time to adjust. When they do not get it, fermentation goes sideways, gas builds, and the conditions for impaction or spasmodic colic are set.
Any change in hay should happen over a minimum of ten to fourteen days. That goes for quality changes too, not just type. A new cutting of the same hay can have meaningfully different nutritional content.
3. Changes in Grain
Changes in concentrate feeding and high concentrate diets are consistently associated with increased colic risk across multiple studies.¹
Dr. Franklin explains the mechanism plainly: "As we feed more grain, more concentrate at one time, what happens is that just passes through the front tube or the foregut faster. And so now we've got all this spillage of starch into the hindgut. Sometimes we would see undigested corn in the manure."
That undigested starch hits the hindgut hard. Bacteria ferment it rapidly, produce acid, drop the hindgut pH, and kill off the beneficial microbes that keep the system stable. Gas production spikes. Feed smaller, more frequent meals. Make any grain changes gradually over at least two weeks.
4. Dehydration
Restricted access to water is one of the consistently identified risk factors for colic across the research literature.¹ Without adequate water moving through the digestive tract, ingesta slows, compacts, and the conditions for impaction colic are set. Grain diets compound this by actively decreasing water content in the colon.
Keep fresh water in front of your horse at all times. During travel, competition, and hot weather, active electrolyte supplementation can stimulate drinking and replace what is lost through sweat. 6666 Electrolyte Recover Powder added to daily feed drives horses to the water bucket. Keep the Paste on hand for hauling and competition days when quick, direct support is needed.
5. Increased Stall Time and Limited Turnout
Limited turnout and increased stall time are associated with increased colic risk.¹ Horses are built to move. Movement drives gut motility. Gut motility keeps ingesta moving through the system and prevents impaction from forming.
Dr. Franklin makes the connection explicit: "Horses that are kept in stalls — that means they're not out grazing." No grazing means no constant forage intake, no fiber mat in the stomach, and no natural buffering of the acid the stomach produces around the clock. The gut slows when the horse does.
When a horse goes into stall rest or reduced work, keep forage in front of them constantly. Movement in any form — hand walking, paddock turnout — helps maintain motility during stall-heavy periods.
6. Sudden Changes in Activity or Environment
Recent changes in housing and activity are consistently identified as risk factors for colic in the literature.¹ The gut thrives on consistency. New environments, travel, weather disruptions, and changes in schedule all add stress to a system that depends on routine.
Dr. Franklin explains how stress directly affects the gut: "That physiological stress from training, from hauling, from being in new environments, from being around new horses, all those things compounding creates a release of cortisol. Cortisol is your stress hormone. Well, what does cortisol do to the stomach? It undermines one of those protective mechanisms that help protect the glandular part of the stomach."
When you know a big change is coming — a show, a long haul, a layup — support the gut proactively before the stress hits, not after.
7. Intestinal Parasites
Poor parasite control is consistently identified as a risk factor for equine colic across multiple studies.¹ A high parasite load contributes to impaction, damages the intestinal lining, and disrupts the microbial environment that keeps fermentation stable.
Regular fecal testing and a strategic deworming program are not optional for a horse with a history of gut issues. Work with your veterinarian to design a targeted deworming plan based on fecal egg counts rather than calendar-based deworming alone.
What All Seven Risk Factors Have in Common
Sudden feed changes. High grain diets. Dehydration. Stall time. Stress. Parasites. They are different problems with one thing in common.
Every single one disrupts the microbial community living in your horse's hindgut.
Research has confirmed that horses with colic show measurably altered gut microbiome composition compared to healthy horses, with reduced microbial diversity and reduced abundance of beneficial Fibrobacter bacteria alongside increases in harmful Streptococcus.²³ Whether those changes cause colic or result from it, the connection between gut microbial health and colic episodes is well established in the current literature.²
Dr. Franklin connects this directly to what happens at a cellular level: "You've got a disturbance in the microbes because you've got too much starch going back there that's being digested by these acid-producing bacteria that kill off the good bacteria, and that erodes that lining of the gut."
The bacterial environment in your horse's hindgut is not just a byproduct of what they eat. It is one of the most important factors in whether they colic or not. Managing the risks on this list is the foundation. Supporting the microbiome daily is what ties it all together.
Causes vs. Risk: Quick Reference
| Risk Factor | Evidence Level | Mechanism |
|---|---|---|
| History of previous colic | Consistently documented across multiple studies¹ | Prior episode indicates susceptibility or unchanged management |
| Change in feed type | Among strongest management-related risk factors¹ | Disrupts hindgut microbial community and fermentation |
| Changes in concentrate feeding | Consistently documented¹ | Excess starch overloads hindgut, drops pH, kills beneficial microbes |
| High concentrate diet | Consistently documented¹ | Sustained hindgut acid overload |
| Dehydration / restricted water access | Consistently documented¹ | Slows motility, promotes impaction |
| Limited turnout / increased stall time | Documented across multiple studies¹ | Reduced motility, reduced gut activity, no fiber mat |
| Poor parasite control | Consistently documented¹ | Intestinal damage, microbial disruption |
8 Management Habits That Lower the Risk
Most colic risk is manageable. These are the daily decisions that add up.
1. Never Let the Stomach Go Empty
"Never let your horse sit in a stall without something to eat," Dr. Franklin says. The horse's stomach produces acid around the clock. When there is no forage to buffer it, that acid damages the stomach lining and creates an inflammatory environment that can travel downstream. For metabolic horses that cannot have unrestricted access, low-quality forage or soaked coastal Bermuda hay keeps that fiber mat in place without the sugar load.
2. Make Every Feed Change Slowly
Hay, grain type, hay quality, forage source. Any change should happen over a minimum of ten to fourteen days. The hindgut microbiome needs time to adjust. Rushing that transition is one of the most consistent triggers in the colic research.
3. Split Grain Into Smaller, More Frequent Meals
"Instead of feeding one or two big grain meals, that is so much better done if you can do that three or four times a day," Dr. Franklin said. Smaller, more frequent feedings reduce the amount of undigested starch reaching the hindgut at once and meaningfully lower the acid and gas production that drives colic.
4. Keep Water in Front of Them at All Times
Clean, fresh water. Any time. Every day. During travel and hot weather, add electrolytes to stimulate drinking and replace what sweat takes out. Dehydration is a direct colic risk factor.
5. Maximize Turnout and Movement
Every hour of turnout is an hour of gut motility. Movement keeps ingesta moving. Build movement into the routine even during stall rest periods.
6. Make Transitions Gradual
Before a big haul, a new environment, a schedule change, or an increase in workload, support the gut before the stress arrives. Cortisol hits fast. The gut responds slower. Give the system a head start.
7. Stay Current on Parasite Management
Annual fecal egg count testing. A targeted deworming protocol designed with your veterinarian. Regular testing tells you which horses need treatment and which do not, which protects against resistance and against unnecessary chemical load on the gut.
8. Support the Microbiome Daily
Managing risk factors changes the environment. A daily gut supplement stabilizes the microbial community that all seven risk factors are trying to disrupt.
6666 Complete Gut Protection was formulated to do exactly that. "They need to have that complete gut supplement going in there the entire time," Dr. Franklin said. "Otherwise those ulcers are just destined to come back." Prebiotics, probiotics, and postbiotics to support and stabilize the hindgut microbial community. L-glutamine and oat beta glucan to protect the stomach lining and support barrier integrity. Both sides of the system covered in a single formula. One scoop for maintenance. Two scoops during high-demand periods including travel, competition, and any time a feed change is unavoidable.
Actionable Checklist: Lowering Your Horse's Colic Risk
- ✓ Keep forage available at all times — never let the stomach sit empty
- ✓ Make all hay and grain changes over a minimum of ten to fourteen days
- ✓ Split grain into smaller, more frequent meals
- ✓ Ensure constant access to fresh, clean water
- ✓ Add electrolytes during travel, competition, and hot weather to stimulate drinking
- ✓ Maximize turnout and daily movement
- ✓ Make exercise and schedule changes gradually
- ✓ Run annual fecal egg counts and work with your vet on a targeted deworming program
- ✓ Know your horse's baseline gut sounds, manure consistency, and water intake
- ✓ Support the hindgut microbiome daily with a full-spectrum gut supplement
- ✓ Increase gut supplement dosing during high-stress periods before problems appear
We Asked the Vets: Your Colic Questions Answered
Is colic actually preventable?
Not entirely, but most episodes are not random. The research consistently shows that the majority of colic cases are associated with identifiable, modifiable risk factors.¹ Knowing those risk factors and working to reduce them meaningfully lowers the odds. No management program eliminates all risk, but the gap between a horse whose gut is supported and one whose is not is significant.
How do I know if a feed change caused a colic?
The timing matters. Colic episodes associated with feed changes typically occur within 48 to 72 hours of the change. If your horse colics shortly after a new hay delivery, a switch in grain, or any change in their feeding program, that connection is worth noting. Going forward, slow all transitions to a minimum of ten to fourteen days.
My horse colicked once. Should I be worried it will happen again?
A history of colic is a genuine risk factor, one of the most consistently documented in the literature.¹ That does not mean another episode is inevitable. It means being more deliberate about every management decision from here forward, and addressing whatever contributed to the first episode.
Does dehydration really cause colic?
Yes. Without adequate water moving through the digestive tract, ingesta slows and the risk of impaction climbs. Grain diets make this worse by reducing water content in the colon. Horses that are not drinking enough, especially during travel, heat, or exercise, are at elevated risk. Electrolytes help stimulate drinking and replace what is lost through sweat.
Can stress really trigger colic?
Yes. As Dr. Franklin explains, cortisol suppresses gut motility, reduces blood flow to the stomach lining, and disrupts the microbial balance in the hindgut. That does not mean you can never haul or compete your horse. It means building recovery and proactive gut support into the routine around those events.
What is the gut microbiome and why does it matter for colic?
The hindgut is home to a complex community of microorganisms that ferment fiber and regulate the entire digestive environment. Research has confirmed that horses with colic have measurably altered gut microbiome composition, with reduced diversity and increased levels of harmful bacteria.²³ Whether these changes cause colic or result from it, supporting the microbial community daily is one of the most important things you can do to lower colic risk.
Should I scope my horse if they have a history of colic?
Work with your veterinarian. If your horse has recurring mild colic episodes, scoping can help determine whether gastric ulcers are contributing. Dr. Franklin notes that horses can have a completely normal scope on the gastric side while the hindgut is the issue. Knowing which side of the system is involved changes the management approach entirely.
When do I call the vet versus wait and see?
Any signs of colic warrant monitoring at minimum. Call your veterinarian immediately if your horse is in obvious pain that is not resolving, has no gut sounds on one or both sides, has elevated heart rate, is unable to pass manure, or has had colic episodes requiring surgery in the past. When in doubt, call. Early treatment produces significantly better outcomes than delayed treatment.
When to Call Your Veterinarian
Contact your veterinarian immediately if your horse shows signs of colic that do not resolve within 20 to 30 minutes of light walking, if pain is escalating rather than improving, if gut sounds are absent, if heart rate is elevated, or if your horse is unable to pass manure. For horses with a history of colic, work with your veterinarian to review current management practices, conduct a fecal parasite evaluation, and consider scoping to rule out gastric ulcers as a contributing factor.
The Takeaway
Know the risks. Manage the routine. Protect the gut that makes everything else possible.
Shop Complete Gut Protection here.
We focus on the whole horse. The science. What works and stands the test of time, not chasing trends or quick fixes.
Formulated by veterinarians. Trusted on the ranch and in the arena. Built for horses that work.
The 6666 Equine Supplements Team
References
- Curtis L, Burford JH, England GCW, Freeman SL. Risk factors for acute abdominal pain (colic) in the adult horse: A scoping review of risk factors, and a systematic review of the effect of management-related changes. PLoS ONE. 2019;14(7):e0219307.
- Lara F, Castro R, Thomson P. Changes in the gut microbiome and colic in horses: Are they causes or consequences? Open Vet J. 2022;12(2):242-249.
- Thomson P, Garrido D, Santibáñez R, Lara F. Preliminary functional analysis of the gut microbiome in colic horses. Animals (Basel). 2024;14(22):3222.
