Genetic evaluation of English bulldogs with cystine uroliths

IN DOGS, only 3 per cent of urolithiasis is represented by a cystine (Ling and others 1998, Osborne and others 1999); according to Bartges and others (1994), English bulldogs are characterised by a cystine urolith frequency 32 times higher than any other dog. In 1977, Brown and others examined 438 uroliths. Among these, 95 were made of a cystine and were mainly found in English bulldogs, Newfoundlands and dachshunds. Later, Chew and others (2011) published research listing the same breeds as the most affected by cystinuria. In English bulldogs, four mutations have been identified at the homozygous level in the SLC3A1 gene, whereas two mutations have been described in the SLC7A9 gene (Harnevik and others 2006). In a recent study, Brons and others (2013) suggested a new classification for cystinuria, which seems to have different characters and involve different genes depending on the breed. In labrador retrievers and mixed breeds, cystinuria is described as an autosomic-recessive disease involving the SLC3A1 gene; in Australian cattle dogs, the disease seems to be autosomic dominant. The aim of this study was to investigate the association between cystine uroliths in some English bulldogs and the genetic mutations in the SLC3A1 and SLC7A9 genes.