Cystinuria is an inherited metabolic defect of amino acid transport in which cysteine, ornithine, lysine, and arginine are transported abnormally in kidneys and intestine. Normally cystine is filtered in renal glomerulus and then reabsorbed back to blood in tubules. This has an effect that only low concentration of cystine is found in urine. Dogs with cystinuria do not absorb cystine in kidney tubules therefore they have abnormally high urine concentrations of cystine. Cysine is not soluble in alkaline or neutral pH, therefore its excess in urine forms crystals that lead to formation of cystine stones in kidney 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 English and French bulldogs three mutations in two different genes were associated with the development of cystinuria. One mutation is inherited in incompletely recessive manner, which means that also heterozygous animals can develop the disease.
Inheritance: autosomal recessive and autosomal incompletely recessive
Mutation: SLC3A1 and 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.
Disease control: read more
Sample: EDTA whole blood (1.0 ml) or buccal swabs. Detailed information about sampling can be found here.