Gas chromatography-mass spectrometric studies of canine urinary metabolism

After the urine was treated with urease, lyophilized, and trimethylsilylated, it was examined for metabolic profiles in Dalmatian dogs and Shetland sheepdogs by gas chromatography-mass spectrometry (GC/MS), which simultaneously analyzes organic acids, amino acids, sugars, sugar alcohols, purine and pyrimidine bases, and nucleosides. The profiles were compared with those from human specimens. As clarified in past studies, Dalmatian dogs showed an extreme decrease in allantoin, which is the final product of purine metabolism in the canine of other species, and a marked detection of uric acid peak. This finding suggests that purine metabolism in Dalmatian dogs is different from that in the other species. Only two Shetland sheepdogs, whose mother had chronic renal failure, showed a marked excretion of uric acid, as in Dalmatian dogs. In addition, some Dalmatian dogs, who were maintained on a protein-restricted diet, showed a little excretion of uric acid. A large amount of uric acid is detected in combination with pentose-monosaccharides, hexose-monosaccharides and sugar alcohols in neonatal human urine in comparison with the present dog samples. A marked difference between the canine and the humans is that phenylacetylglycine, which is derived from the aromatic amino acid phenylalanine, is excreted in the canine urine. Phenylacetylglycine is not detected in the human urine, and there have been no reports of its excretion in canine urine.