Common "grass founder," the bane of fat ponies and aged broodmares, might be the key to understanding the bigger picture of systemic laminitis according to a recent study completed by Christopher C. Pollitt, BVSc, PhD, of the Australian Equine Laminitis Research Unit at the University of Queensland. Pollitt presented 10 seminars on the role of fructan in laminitis across Europe in early March of 2002.

Karen Hinckley, PhD, of the University of Sheffield, proposed in 1997 that fluctuating fructan (a water-soluble carbohydrate) levels in pasture grass was a factor in developing grass founder. Pollitt took note of this and the subsequent work of Longland & Cairns of the Institute of Grassland & Environmental Research, Aberyswth, UK, and spent two years confirming that fructan does directly cause laminitis by disrupting the balance of microflora in the equine hindgut. At sufficient doses, the fructan induces digestive upset and will cause an uncontrolled activation of MMPs (matrix metalloproteinases; these enzymes are thought to be a factor in laminar degradation), triggering laminitis.

"In preliminary trials, we have induced mild laminitis by administering commercially available fructan," Pollitt reported. "A dose of 7.5g/kg (of body weight) results in laminitis 48 hours later; (this is) one-half the amount of starch (such as found in sweet feed) required to induce laminitis.

"The animals developed a fever and diarrhea, just as they do with the starch induction model (veterinary science’s usual method of inducing laminitis for research), but without colic. By 36 hours, the animals’ normal appetites, metabolism, and feces returned, but they had laminitis, confirmed by histopathology