Grass is safest when it is between 4 and 6 inches in height. A common misconception is that because the pasture is “sparse” and overgrazed, there is no danger. How much could they really be eating anyway? Maybe not a lot, but what they are consuming is extremely high in fructans. When grass is overgrazed and short, it is struggling to survive, stressed out. So even though they’re not able to consume large quantities, they graze more and longer on the sweet, tasty sugar! Horses will almost ALWAYS migrate to those “patches” of overgrazed grass before they will eat the taller grass. This is because the short stuff contains more sugar and, of course, because horses have a “sweet tooth”, they prefer it. But don’t be too sure that this isn’t detrimental for your horse!
There are many things one can do to maintain pastures. Creating a “track” system around the perimeter with access to hay, turning them out in the middle for periods at a time (on grass that is properly maintained), will keep your pasture from being overgrazed. A rotation system in which your pasture is separated into smaller sections works well also. This allows you to graze your horses on one pasture at a time, allowing the other sections to “rest”. These are only a couple examples of easy ways to ensure that your grass is as safe as possible.
If your horse is IR and has had a laminitic episode, we do encourage you to keep your horse off of grass. Maybe not for life, but at least until your horse has a chance to recover. There are certain times in which the grass is more stressed. This can be a “trigger” for your IR horse. There are a lot of things that determine if the grass is “safe” and there are certain times in which the grass is stressed, increasing the fructans (sugar). Spring and fall seasons, for up to 3 days after it is mowed, during a drought, right after it rains, during the heat of the day, when the grass has been covered and insulated by snow, etc. For an IR horse, especially one that is continually experiencing laminitic episodes on a regular basis, keeping them off of grass and offering free choice hay is imperative. A large dry lot is ideal, so that you can spread the hay around in smaller piles, giving your horse the ability to “graze” and move about as he or she wishes. A horse that is “grazing” and moving is a happy horse, no matter what they’re eating. If they have a full tummy, they’re happy!