Yes, fall pasture grass can cause laminitis. As the air gets cooler and the leaves begin to change, so does your pasture grass. The sugars in grasses rise as new growth explodes with cooler temperatures and fall rains, increasing the risk of laminitic episodes. If a horse looks foot sore contact your veterinarian and start soaking their feet in ice water as soon as symptoms appear.
Take extra care when fall grazing horses who suffer from metabolic disorders. Their bodies do not metabolize sugar properly and are at a higher risk of pasture-induced laminitis.