Digital vascular responses and permeability in equine alimentary laminitis

Digital vascular pressures, blood flow, and vascular resistances were measured in 11 control ponies and in 8 animals (7 ponies and 1 horse) affected with laminitis created by feeding a high starch ration. Animals with laminitis had increased digital blood flow, increased arterial, small vein, and large vein pressures, and decreased vascular resistances. Comparison of digital lymph flow rates and protein concentrations in animals with laminitis and control animals revealed no differences. Digital vascular responses of the 2 groups to acetylcholine, epinephrine, histamine, or serotonin also did not differ. Thus, the increased digital blood flow observed in animals with laminitis could not be attributed to altered responsivenss to the previously mentioned vasoactive agents. The studies also provided no evidence for increased capillary permeability in digits of animals affected with laminitis.