XANTHINURIA IN A FAMILY OF CAVALIER KING-CHARLES SPANIELS

Xanthine calculi mere found in a 7-month-old male Cavalier King Charle s spaniel with urethral obstruction and renal insufficiency, Because t he only two other reported cases of naturally occurring xanthine uroli thiasis concerned a Cavalier King Charles and a King Charles spaniel t he urine of the littermates and parents of the patient mere also exami ned for xanthinuria. Semi-quantitative analysis revealed high urine co ncentrations of hypoxanthine and xanthine in the patient and his femal e littermate. Quantitative analysis by high-pressure liquid chromatogr aphy (HPLC) of the urine samples from the family of this Cavalier King Charles spaniel and nine control dogs revealed that hypoxanthine and xanthine excretion was 30 and 60 times higher in the affected patient and the female littermate than in the others dogs, The pattern of xant hinuria, which is caused by a deficiency of the enzyme xanthine oxidas e, in the relation diagram of this family of Cavalier King Charles Spa niels was consistent with an autosomal recessive mode of inheritance.