A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate [[analgesia]], a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of [[sodium chloride]] and sodium sulphate orally, to create an [[osmotic]] gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin ([[Mineral oil]]) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.