Why Gradual Introduction to Grass Matters for Horses
Are you eager to turn out your horses to your newly green pasture? Although grass provides important nutrients, a rapid introduction to grass could cause health issues like diarrhea, colic, and laminitis.
How Grass Can Cause Trouble for Your Horse
Horses are born grazers and enjoy nothing more than munching on pasture grass. While grazing provides nutrients and keeps your horse active and engaged, eating new grass (known as "lush" grass) in the spring can lead to problems.
Food spends relatively little time in the stomach, as digestion happens primarily in the horse's hindgut. The hindgut consists of the large colon and the cecum, the first part of the large intestine. Bacteria and other microbes in the hindgut ferment fibers in foods, which breaks them down and helps the body use nutrients and carbohydrates (sugar).
Over the winter, your horse's digestive system adjusts to the forage or feed you provide. A quick shift to a lush grass-based diet in the spring can upset the system's delicate balance.
Spring grass contains higher amounts of sugar and starches and less fiber, according to the University of Illinois Urbana-Champaign College of Veterinary Medicine. Changes in the microbial balance can lead to gas, inflammation, or the release of toxins.
If your horse begins eating grass too quickly, it may be more likely to develop one of these health issues:
- Diarrhea. Loose stools, dehydration, and weight loss can happen if your horse eats too much grass too soon.
- Colic. Gas buildup in the intestines can cause colic (abdominal pain), a painful, potentially serious condition in horses. If your horse has colic, its abdomen may look larger than normal due to bloating. Horses with colic may roll on the ground, kick their bellies, or fail to pass manure due to a blockage or impaction. The risk for colic increases two or three weeks after changes to diet, exercise, or stabling, according to the University of Minnesota Extension.
- Laminitis. Too much sugar in the diet can increase inflammation and cause grass founder, a type of laminitis. If laminitis is severe, the coffin bone may separate from the hoof wall and rotate inside the hoof capsule, triggering lameness. Horses that have metabolic disorders, are overweight, or are insulin-resistant may be more likely to develop laminitis.
Introducing Your Horse to Grass Gradually
A gradual introduction to grass will help your horse avoid painful colic, laminitis, and uncomfortable diarrhea. Following these tips can reduce the risk of health issues:
- Wait Until Grass Is 6" to 8" High Before Turning Out Your Horse
- Offer Access to Pasture Grass for 15 to 30 Minutes at First, Then Extend the Amount of Time Your Horse Spends in the Pasture by 15 to 30 Minutes Every Few Days
- Provide Hay Before Turn Out to Decrease Your Horse's Appetite for Grass
- Follow PetMD's Advice and Turn Your Horse Out Between 3 a.m. and 10 a.m. When Sugar in Grass is Lower
- Use a Grazing Muzzle If Your Horse Is Overweight or Has Cushing's Disease, Metabolic Syndrome, or Laminitis
- Rotate Pastures to Prevent Overgrazing
- Watch Your Horse for Signs of Digestive Issues, Colic or Laminitis During the Introduction Period
- Ask Your Veterinarian About the Ideal Grass Introduction Schedule for At-Risk Horses
Do you need help creating a turnout plan for your horse? Contact our office to schedule an appointment with the veterinarian.
Sources:
PetMD: How To Introduce Your Horse to Grass, 10/7/2023
https://www.petmd.com/horse/how-introduce-your-horse-grass
University of Minnesota Extension: Colic in Your Horse, 2021
https://extension.umn.edu/horse-health/colic-your-horse#what-to-do-if-your-horse-colics-71562
The Horse: Transitioning Horses to Spring Pastures, 4/28/2025
https://thehorse.com/199596/transitioning-horses-to-spring-pastures/
University of Illinois Urbana-Champaign College of Veterinary Medicine: Spring Grass and Laminitis in Horses, 3/12/2022
https://vetmed.illinois.edu/pet-health-columns/spring-grass-and-laminitis-in-horses/
Kentucky Equine Research: Answer Exchange
https://ker.com/equinews/answer/equine-nutritionist-qa-introducing-new-pastures/
University of Minnesota Equine Extension: Spring Horse Tips, 5/17/2023