Urate Metabolism - Pathology

The final product or purine degradation is uric acid which, under normal circumstances, is excreted in the urine in a more water soluble form. Mammals (except primates) oxidise uric acid to allantoin using the copper-containing enzyme urate oxidase. Hyperuricaemia occurs when the uric acid is not removed from the blood and converted to allantoin by the liver, a failure of any one of the steps in the metabolic pathway. In the Dalmatian dog there is impaired urate transport in to the hepatocyte (and also decreased renal reabsorption leading to urate calculi formation). Urate calculi in other breeds are associated with porto-systemic shunting.