Cystinuria is an inherited metabolic defect of amino acid transport in which cysteine, ornithine, lysine, and arginine are transported abnormally in kidneys and in the intestine. Normally cysteine is filtered in renal glomerulus and then reabsorbed back to the blood in tubules. Consequently, only low concentration of cysteine is found in urine. Dogs with cystinuria do not absorb cysteine in kidney tubules, therefore they have abnormally high urine concentrations of cysteine. Cysteine is not soluble in alkaline or neutral pH, therefore its excess in urine forms crystals that lead to formation of cysteine stones in kidneys or bladder. Affected dogs often have inflammation of urinary system and have increased risk for urinary blockage which leads to kidney failure, rupture of bladder and death, if not treated immediately. In Miniature Pinschers, type II-b cystinuria occurs, which has autosomal dominant mode of inheritance. First clinical symptoms usually appear at 1 or 2 years of age.
Inheritance: autosomal dominant - read more
Mutation: SLC7A9 gene
Genetic test: The method used for testing is extremely accurate and allows complete differentiation between affected animals, carriers and healthy dogs. Testing can be done at any age.
Sample: EDTA whole blood (1.0 ml) or buccal swabs. Detailed information about sampling can be found here.