Cystinuria, type II-B in Miniature Pinschers

Cystinuria is an inherited metabolic disorder of amino acid transport in the kidneys. In affected individuals, cystine accumulates in the urine and its excess in urine forms cystine crystals that lead to formation of urinary stones. These irritate the urinary tract, causing urinary stagnation and increasing the susceptibility of the urinary tract to infection. Clinically, cystinuria is manifested by dark and distinctly foul-smelling urine with an admixture of blood. Urination is painful and often unsuccessful.

Cystinuria has been observed in more than 60 dog breeds.  However, it is a genetically heterogeneous disease, and the clinical manifestations vary from breed to breed. In Miniature Pinschers, the disease is caused by a single base missense mutation (c.964G>A) in the SLC7A9 gene. Inheritance of the mutation is autosomal dominant. This means that only one copy of the mutated gene inherited from one of the parents is needed to cause symptoms of the disease.

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References:

Brons, A.K., Henthorn, P.S., Raj, K., Fitzgerald, C.A., Liu, J., Sewell, A.C., Giger, U.: SLC3A1 and SLC7A9 mutations in autosomal recessive or dominant canine cystinuria: a new classification system. J Vet Intern Med 27:1400-8, 2013. Pubmed reference: 24001348