Urogenital tract abnormalities include inflammation, hemorrhage and ulceration of the bladder mucosa, ureters and renal pelvis. The urethra is occasionally affected to a lesser extent. The kidneys may appear pale, moist and slightly swollen. Cardiac lesions, when present, consist of striate to patchy areas of ventricular myocardial necrosis. Pericardial effusion is occasionally observed.
Hypovolemic shock develops rapidly in more severely affected horses.
Because of the disruption in the intestinal mucosa, the normal transfer of fluid, nutrients and electrolytes across the mucosal lining is disrupted. Mild renal lesions may also play a role in the development of fluid, acidbase and electrolyte abnormalities seen in some horses. The development of hypoproteinemia may be due to loss of protein through the damaged intestinal mucosa. Although mild proteinuria occurs in affected horses, the amount of protein lost through the urine does not account for the decline seen in serum protein concentrations. Hypocalcemia and hypomagnesemia occur in many horses for undetermined reasons.