Psyllium is a rich source of soluble fiber that can be incorporated into equine diets to support digestive health. The soluble fiber remains undigested by enzymes in the stomach and passes into the hindgut where it is partially digested by microbes.

Psyllium is commonly fed to horses to facilitate sand clearance, support hindgut function and metabolic health, and to promote hydration and reduce ulcer risk in performance horses.

Psyllium may also be used as part of treatment protocols for sand impaction colic. In this application, a veterinarian administers psyllium with a nasogastric tube directly into the horse’s stomach for three days to two months or longer.

While feeding psyllium to horses offers potential benefits, it’s important to closely follow feeding guidelines to prevent the formation of bezoars, tightly packed masses of psyllium that may cause impaction. To determine the appropriate use of psyllium in your horse’s diet, consult an equine nutritionist or your veterinarian for individualized recommendations.

Psyllium for Horses

Psyllium is commonly harvested from the Plantago Ovata plant, a member of the Plantaginaceae family. Plantago Ovata is grown in regions of India, Asia, the Mediterranean, and North Africa. This plant has been used medicinally for centuries.

Psyllium husk is a fiber-rich supplement that is a byproduct of psyllium seed production. The chemical structure of psyllium husk includes many hydroxyl groups, which enable it to have a high capacity for absorbing water. [1]

When ingested by horses, psyllium absorbs water from the gut and acts as a bulking fiber that promotes the movement of digesta through the intestines. As such, psyllium can support gut motility and the clearance of indigestible material from the gastrointestinal tract.

The soluble fiber in psyllium remains largely undigested by the horse, but can be partially digested by microbes in the hindgut, helping to support microbial diversity. [2]

Psyllium Husk for Horses

Benefits of Feeding Psyllium

Feeding psyllium to horses offers several benefits, particularly related to digestive health: [1][3][4][5][6]

  • Sand Accumulation: Psyllium helps to promote sand clearance in the intestines, potentially reducing the risk of blockages and impaction colic
  • Hindgut Microbiome: As a soluble fiber, psyllium can support the health of the hindgut by providing a substrate for beneficial microbial fermentation, potentially supporting the hindgut microbiome
  • Metabolic Concerns: Psyllium may support normal blood glucose regulation by slowing down the absorption of sugar from the gut, helping to maintain metabolic health in horses with insulin resistance (IR)
  • Athletic Performance: Feeding psyllium to competition horses has been shown to support hydration during endurance races and may help reduce the risk of gastric ulcers

Psyllium Supplements

There are a number of psyllium-based equine digestive supplements on the market. These supplements should be administered according to manufacturer guidelines to avoid complication related to gut health.

Horse owners also sometimes feed generic psyllium husk products or supplements not designed for equine use. When feeding products that are not formulated specifically for horses, it’s important to consult with your veterinarian or a nutritionist to make sure the product is safe and formulate an appropriate feeding plan.

If feeding a powdered form of psyllium husk, it can be helpful to wet down your horse’s meal to improve palatability and ensure proper hydration.

Sand Accumulation & Colic

In areas with sandy soil, it’s easy for horses to ingest sand through foraging and other behaviors. Ingested sand can accumulate in the large colon and potentially cause digestive blockages or irritation, putting the horse at risk of sand colic.

The risk of sand colic is greater in horses that are fed on the ground, as well as those that are housed on over-grazed pastures.

Standard treatments for horses with sand accumulation include: [1]

  • Removing the horse from sandy areas
  • Administering enteral or parenteral hydration (administering water into the gastrointestinal tract)
  • Administering laxatives

Psyllium is commonly used as a natural laxative in horses affected by sand accumulation and colic. Psyllium is thought to form a gel-like mixture in the digestive tract, encapsulating sand and facilitating its excretion in feces.

Despite the popularity of psyllium husk for sand elimination, research has shown mixed results regarding efficacy. Studies show that the efficacy of psyllium appears to depend on the route of administration and whether it is used in combination with other interventions.

Nasogastric Administration

For horses with sand accumulation, nasogastric intubation of psyllium appears to be the most effective route of administration. This procedure involves your veterinarian inserting a tube through the horse’s nose, down the esophagus, and into the stomach to directly deliver a solution of psyllium into the digestive tract. [7]

In research studies that involve nasogastric tubing, the duration of psyllium treatment typically lasts between 3 – 7 days with 1 – 2 treatments administered per day. Dosages of psyllium are typically 1 gram per kilogram (1 g/kg) of the horse’s body weight, equal to 500 grams per day for an average horse weighing 500 kg (1100 lb).

Research suggests psyllium is most effective in clearing sand impaction when combined with other laxatives. Nasogastric intubation of psyllium in combination with magnesium sulfate (epsom salt) is most effective, fully clearing sand from up to 75% of horses. [7][8]

Administering psyllium and/or magnesium sulfate daily via nasogastric tubing for 3 – 7 days also appears to be more effective than a single intubation treatment or home feeding psyllium for ten days. [9]

Further, ponies fed or intubated with psyllium alone showed no improvement in sand clearance compared to control horses not treated with psyllium at all. [10] This suggests combination with a laxative such as magnesium sulfate is important to achieve optimal results.

Nasogastric intubation should only be performed by a veterinarian. There is no safe way to intubate a horse at home.


Feeding Directions

Although intubation is a commonly studied method of administration for sand clearance, some data suggests feeding psyllium to horses may encourage sand clearance as part of routine management.

In healthy horses, feeding a supplement containing psyllium, probiotics, and prebiotics for 35 days resulted in increased sand clearance from the digestive tract. [11] This effective dose established in this study was 200 grams of psyllium product per day for 35 days. [11]

Although extended feeding of psyllium was shown to be effective, it’s possible for microbes in the gut to adapt and start degrading psyllium in the tract over time. As such, it may be more effective to feed psyllium for shorter periods to maintain its sand clearing properties on an ongoing basis.

However, these results warrant further investigation, as a more recent study of a psyllium, prebiotic, and probiotic supplementation showed no differences in sand clearance compared to the placebo group. [12] In another study of horses fed psyllium for 29 days, sand clearance was not increased with psyllium treatment alone. [13]

A further study examined the effects of mineral oil intubation combined with psyllium feeding for sand clearance. Following five days of combined treatment, horses on mineral oil and psyllium cleared 51% of ingested sand, whereas horses receiving only mineral oil cleared 26% of the sand. [14]

While at least one study shows that feeding psyllium can promote clearing sand from the digestive tract, other studies provide mixed results. Available research suggests it may be beneficial to supplement probiotics and prebiotics as well and that nasogastric intubation is still a more effective method of administration.

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Hindgut Support

Psyllium is commonly used in human medicine to support digestive health and promote regular bowel movements. When ingested by humans, psyllium fiber is not degraded in the small or large intestine and traverses the entire digestive tract. [#] This makes it effective for improving stool quality, particularly in cases of constipation, diarrhea, and irritable bowel syndrome (IBS). [15]

These results have led to interest in using psyllium for potential digestive benefits in horses. Unlike in humans, psyllium use in horses is broken down by microbes in the hindgut. As such, it may serve as a useful substrate for microbial fermentation in the hindgut, meaning it may enhance the growth and activity of beneficial gut bacteria. [2]

Research in horses shows that psyllium can increase microbial diversity, which is associated with improved hindgut health. Moreover, supplementing with psyllium has been found to boost the production of microbial mycothiol (an antioxidant) and indicators of urea utilization by microbes (a sign of microbial growth). [3]

In a study of horses fed different amounts of psyllium, supplementation was also shown to decrease total gas and methane production, suggesting potential environmental benefits by reducing methane gas emissions in horses. However, psyllium also reduced feed digestibility in horses, which could negatively impact a horse’s ability to extract nutrients from their feed. [16]

Feeding Directions

Positive effects on hindgut microbial fermentation have been observed when feeding horses psyllium supplements at doses between 50 – 400 grams per day for a period of 1 – 2 weeks.

Psyllium is commonly cited as a component of feeding protocols to support hindgut issues, such as free fecal water syndrome (FFWS) in horses. [17][18] While there are anecdotal case reports of its use, it’s important to note that the use of psyllium for FFWS has not been investigated.

Always consult with your veterinarian or an equine nutritionist before adding psyllium to your horse’s diet to support specific hindgut concerns.

Metabolic Health

The positive effects of psyllium on metabolic health in humans are well-documented and include: [15]

  • Improving blood sugar control in patients with metabolic syndrome and diabetes
  • Reducing high cholesterol levels
  • Supporting satiety (appetite control), leading to lower caloric intake and weight loss

These benefits are attributed to increased viscosity (thickness) of food passing through the gastrointestinal tract, slowing the rate of digestion and absorption of glucose (sugar). This has spurred interest in psyllium as a supportive supplement for horses with metabolic issues.

Research shows horses receiving psyllium for 60 days had lower blood glucose and insulin levels following a meal compared to horses in a control group. In addition, horses receiving psyllium showed lower peak glucose concentrations in their blood after receiving a glucose infusion. [4]

Similarly, in a study of horses grazing rapidly growing, cool-season grasses known to be high in sugar, those supplemented with psyllium daily showed reduced glucose responsiveness. [19] This means that the horses fed psyllium had a more moderated blood sugar response when grazing on high-sugar grasses, potentially reducing the risk of metabolic issues.

Additional research in healthy horses showed lower protein and triglyceride levels in the blood after 29 days of supplementation with psyllium. Reduced triglyceride levels suggest a metabolic benefit to feeding psyllium, but lower serum protein concentrations suggest that psyllium also alters protein digestion and absorption in horses. More research is needed to understand the effects of psyllium supplementation on protein metabolism. [20]

While some studies suggest benefits for blood sugar regulation from psyllium, other researchers have found no difference in glucose concentrations in response to 42 days of psyllium supplementation. [21] The researchers in this study also observed higher peak insulin levels and an increase in neck circumference in horses fed psyllium, but no differences in body weight or tailhead fat deposits.

Conversely, another study conducted by the same researchers with a larger number of horses revealed lower glucose, insulin, and adiponectin levels in horses supplemented with psyllium. [22] These differing results indicate more research is needed to determine if there is a metabolic benefit to feeding psyllium in horses.

Feeding Directions

In research studies, psyllium supplementation has produced benefits for metabolic health when fed to horses at a dosage between 90 – 270 grams per day for 30 – 60 days.

To confirm whether this supplement is effective for your horse, it can be helpful to have your veterinarian review your horse’s bloodwork before and after adding psyllium to their diet.

Athletic Performance

There’s growing interest in using psyllium as a performance supplement for horses due to its ability to absorb and retain water as it moves through the gastrointestinal tract. This may help support hydration status in working horses.

In a study of competing endurance horses, psyllium supplementation was shown to limit the increase in hematocrit (an indicator of hydration status) following a 120 km (75 mile) ride. [5]

Researchers believe that increased hematocrit stability in horses supplemented with psyllium may be due to increased water holding capacity in the intestines. Feeding psyllium to horses prior to endurance races may provide a means of maintaining hydration during competition, reducing the risk of dehydration and heat stress. [5]

In addition to supporting hydration, the use of psyllium may reduce the severity of gastric ulcers in competition horses. Research shows that feeding a supplement containing psyllium, minerals, prebiotics, and yeast to horses with gastric ulcers resulted in reduced ulcer scores in stock-type and performance horses. [6]

Feeding Directions

To support hydration in performance horses, it is recommended to feed psyllium at a dose of 150 grams per day for eight days preceding endurance competitions. [5] These dosage recommendations are based on an average 500 kg (1100 lb) horse and should be adjusted based on your horse’s body weight.

To support gut health in working horses prone to gastric ulcers, feeding a 300 gram combination supplement with psyllium, minerals, prebiotics, and yeast for four weeks has been found effective. [6]

If your horse has a history of stomach issues, there are a number of additional feeding strategies and nutritional supplements that can help. Consult with an equine nutritionist for help determining the best feeding program to optimize your horse’s performance.


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Is Psyllium Safe for Horses?

Feeding psyllium to horses is generally considered safe, but it’s important to follow manufacturer’s guidelines based on the product you are feeding. Before feeding high dosages or long-term use, consult with a veterinarian to ensure your horse’s safety.

Overfeeding this supplement has been shown to result in the formation of psyllium bezoars, which are compacted balls of digesta in the gastrointestinal tract. In one case, psyllium bezoars caused gastric rupture in a horse.

Veterinarians determined that the rupture was a result of the horse ingesting psyllium at a rate four times higher than the suggested daily dosage. [23] For this reason, it’s important to closely follow manufacturer guidelines and use psyllium as directed by a veterinarian or nutritionist.


Psyllium supplements are rich in soluble fiber, which may support benefits for digestive and metabolic health in horses.

  • Psyllium appears to be most effective for sand clearance when administered nasogastrically with other laxatives.
  • Psyllium can be digested by microbes in the horse’s the hindgut, which may have positive impacts on hindgut microbial diversity.
  • Feeding psyllium may also be beneficial for horses with metabolic concerns and help promote hydration in competition horses.
  • Following veterinarian or nutritionist dosage recommendations can prevent negative health outcomes associated with overfeeding psyllium.

While psyllium may support gut health in horses, it should always be used as part of a comprehensive management plan that includes adequate hydration, a balanced diet, regular turnout and routine veterinary check-ups to monitor for health problems.

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  1. Loschelder, J., & Gehlen, H. Sand Colic in the Horse-Review and Case Examples. Pferdeheilkunde. 33(6), 591–596. 2017.
  2. Po, B. T., et al. Effect of Psyllium Husk Supplementation on Equine Fecal Nutrient Composition and in Vitro Fermentation. Journal of Equine Veterinary Science. 124, 104399. 2023.
  3. Mienaltowski, et al. Psyllium Supplementation Is Associated with Changes in the Fecal Microbiota of Horses. View Summary
  4. Moreaux, S. J. J., et al. Psyllium Lowers Blood Glucose and Insulin Concentrations in Horses. Journal of Equine Veterinary Science. 31(4), 160–165. 2011.
  5. Cinotti, S., Guglielmini, C., & Boari, A. The Effect of Psyllium on Some Haematological and Biochemical Variables in the Plasma of Horses during an Endurance Ride: Preliminary Results. Pferdeheilkunde. 13(1), 23–26. 1997.
  6. Wagner, A. L., et al. Impacts of Gastro-Well on Gastric Ulcer Prevalence of Competition Horses in Canada. Journal of Equine Veterinary Science. 76, 42. 2019.
  7. Niinistö, K. E., et al. Investigation of the Treatment of Sand Accumulations in the Equine Large Colon with Psyllium and Magnesium Sulphate. The Veterinary Journal. 238, 22–26. 2018. View Summary
  8. Niinistö, K., et al. Comparison of the Effects of Enteral Psyllium, Magnesium Sulphate and Their Combination for Removal of Sand from the Large Colon of Horses. The Veterinary Journal. 202(3), 608–611. 2014. View Summary
  9. Kaikkonen, R., et al. Comparison of Psyllium Feeding at Home and Nasogastric Intubation of Psyllium and Magnesium Sulfate in the Hospital as a Treatment for Naturally Occurring Colonic Sand (Geosediment) Accumulations in Horses: A Retrospective Study. Acta Veterinaria Scandinavica. 58, 1–6. 2016. View Summary
  10. Hammock, P. D., Freeman, D. E., & Baker, G. J. Failure of Psyllium Mucilloid to Hasten Evacuation of Sand from the Equine Large Intestine. Veterinary Surgery. 27(6), 547–554. 1998. View Summary
  11. Landes, A. D., et al. Fecal Sand Clearance Is Enhanced with a Product Combining Probiotics, Prebiotics, and Psyllium in Clinically Normal Horses. Journal of Equine Veterinary Science. 28(2), 79–84. 2008.
  12. Hassel, D. M., Curley, T., & Hoaglund, E. L. Evaluation of Fecal Sand Clearance in Horses with Naturally Acquired Colonic Sand Accumulation with a Product Containing Probiotics, Prebiotics, and Psyllium. Journal of Equine Veterinary Science. 90, 102970. 2020. View Summary
  13. Mienaltowski, M. J., et al. Psyllium Supplementation Is Associated with Changes in the Fecal Microbiota of Horses. BMC Research Notes. 13, 1–6. 2020. View Summary
  14. Hotwagner, K., & Iben, C. Evacuation of Sand from the Equine Intestine with Mineral Oil, with and without Psyllium. Journal of Animal Physiology and Animal Nutrition. 92(1), 86–91. 2008. View Summary
  15. McRorie Jr, J. W., et al. Psyllium: The Gel-Forming Nonfermented Isolated Fiber That Delivers Multiple Fiber-Related Health Benefits. Nutrition Today. 56(4), 169–182. 2021.
  16. Kanber, K., & Baytok, E. Effect of Different Level of Psyllium Supplementation to Horse Diet on in Vitro Fermentation Parameters and Methane Emission. İstanbul Üniversitesi Veteriner Fakültesi Dergisi. 43(1), 12–18. 2017.
  17. Theelen, M., et al. Free Faecal Water: What Do We Know and Can Equine Faecal Microbiota Transplantation Be Used to Manage This Issue? In Small Things: European Equine Health & Nutrion Congress. 2019, 36–43. View Summary
  18. Lindroth, K. M., et al. Feeding and Management of Horses with and without Free Faecal Liquid: A Case–Control Study. Animals. 11(9), 2552. 2021. View Summary
  19. Rohrs, J. L. Metabolic and Morphometric Effects of Psyllium Supplementation in Horses Grazing Rapidly Growing Cool Season Grasses. Montana State University-Bozeman, College of Agriculture. 2013.
  20. Helmecke, P. Effects of Psyllium Supplementation on Serum Protein, Triglycerides, Electrolytes and Packed Cell Volume in Horses Grazing Rapidly Growing Cool Season Grasses. Montana State University-Bozeman, College of Agriculture. 2013.
  21. Peterson, J. L., et al. Metabolic and Physical Effects of Psyllium Supplementation on Quarter Horses. American Society of Animal Science. 2009, 176.
  22. Peterson, J. L. Psyllium Lowers Blood Glucose and Insulin Concentrations in Horses. Montana State University-Bozeman, College of Agriculture. 2010.
  23. Bergstrom, T. C., Sakai, R. R., & Nieto, J. E. Catastrophic Gastric Rupture in a Horse Secondary to Psyllium Pharmacobezoars. The Canadian Veterinary Journal. 59(3), 249. 2018. View Summary