Fanconi syndrome in a Labrador retriever.

A 2-year-old male Labrador Retriever was presented to the University of Missouri Veterinary Teaching Hospital with the primary complaints of polydipsia, polyuria, and joint or muscle pain. Low blood urea nitrogen concentration, hyperchloremia, and marked proteinuria were the only abnormalities in a serum biochemical profile and urinalysis. Decreased creatinine clearance and increased renal fractional excretion of sodium, potassium, calcium, and phosphorus were detected by renal clearance studies. Increased excretion of most amino acids was found by amino acid analysis of urine, but not all amino acids were lost with equal magnitude. Amino acids with secondary amino groups or basic side chains were lost at increased rates, whereas those with acidic side chains were not. These differences could be related to defects in specific renal amino acid transport mechanisms. Identification of these transport mechanisms may allow for pharmacologic intervention at the point of renal loss to alleviate clinical signs of disease.