Xanthinuria is a descriptive term for excess urinary excretion of xanthine. Xanthine is a nitrogenous by-product of the metabolism of certain proteins. It is normally found in the muscles, liver, spleen, pancreas, and urine, and is broken down and degraded to uric acid by enzymes. Xanthinuria is classified into two forms. Type I xanthinuria is the result of a deficiency of xanthine dehydrogenase enzyme. Type II xanthinuria is characterized by a deficiency of xanthine dehydrogenase and aldehyde oxidase. When there is a deficiency of one or two enzymes, xanthine accumulates in the plasma and urine and causes disorders of blood vessels, muscles, kidneys, bladder stones, and kidney failure. In dogs and cats, xanthinuria is an uncommon metabolic disorder that is clinically manifested as urolithiasis. The disease has been reported in the Cavalier King Charles Spaniel, Dachshund, and Himalayan cats.

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Xanthine stone disease affects multiple organ systems. The primary organs affected are the kidney and, to a lesser extent, skeletal muscles and joints. Kidney complications are initiated by the formation of xanthine crystals in the tubules, leading to stone formation. Irritation of the tubular epithelium by xanthine crystals results in hematuria (blood in the urine), whereas renal tissue deposits induce an inflammation of the kidneys. Further kidney complications include acute and chronic kidney failure. In addition, xanthinuria often leads to Urolithiasis.

The stones can be removed surgically, but the disease tends to recur. High fluid intake is the key to therapy. Dehydration is to be avoided whenever possible. Since alkalinization of the urine has little affect upon the solubility of xanthine, it adds little to the therapeutic regimen. Allopurinol, an inhibitor of xanthine oxidase enzyme, is sometimes recommended to decrease urinary uric acid excretion. Allopurinol treatment must be accompanied by a low purine diet.3 Foods with high purine content such as liver, kidney, bacon, veal, venison, turkey should be avoided.


  1. Xanthine urolithiasis in a cat: a case report and evaluation of a candidate gene for xanthine dehydrogenase. Journal of Feline Medicine & Surgery , Volume 9 , Issue 6, Pages 503 - 508S . Tsuchida, A . Kagi, H . Koyama, M . Tagawa
  2. Michael E. Moran. Uric Acid Stone Disease
  3. P. Nagaraja Rao, Nagaraja P. Rao, John P. Kavanagh, Glenn M. Preminger. Urinary Tract Stone Disease

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