Managing a Horse with Laminitis on Grass Pastures

Posted: May 7, 2013

If a horse is prone to laminitis special care needs to be considered when allowing the horse to grass on pasture grasses.

The Danger of Fructans and Sugars in Grasses During Certain Conditions

In the Northeastern US, all of the cool season grasses will accumulate fructans and sugars under certain environmental conditions.

  • Timothy and Orchard grass have been reported to accumulate less than ryegrass.
  • The highest sugar accumulations are after overnight cold spells less than 32 degrees Fahrenheit followed by bright sunshine, or just after cutting, or during droughts.
  • As long as the temperature overnight is above freezing, the lowest content of sugars is between 6 AM - 10 AM.
  • Graze horses during the active growing seasons (spring and early summer.) Remember, that the late summer grass such as brown grasses can be very high in sugars.
  • Pastures are healthiest for horses (lowest in sugars) during the active growing season when plants are green and not stressed (not burned out).
  • Implement a good rotational grazing system on your farm to avoid overgrazing. (See  
  • The greatest amount of sugar in a grass plant is in the bottom three inches, so rotate pastures before they are grazed below three inches.
  • Shady pastures and cloudy days will result in lower carb and sugar levels in grasses. Or move high risk horses to shady pastures.
  • Restricting access to only the early morning hours during the summer.
  • Keep at-risk horses off pasture one or two days after mowing, or if there is a drought or after an overnight freeze.
  • Restrictions on grazing can help reduce the risks.


Contact Information

Ann Swinker
PSU Extension Equine Specialist