These disorders can affect the small intestine (commonest in cats) or the large intestine (commonest in dogs).
Proposed causes are :
Immune disorders - Several possibilities have been suggested. The low concentrations of IgA reported in the intestine of German Shepherd Dogs may be a factor leading to reduced local immunity allowing antigens to cross the mucosal barrier of the intestine , and there setting up an inflammatory response in the lamina priopria.
It is a common occurrence in cats.and forms part of the Triad syndrome (IBD with pancreatitis and cholangiohepatitis)