Cystinuria in an Australian Cattle Dog Family-A Seemingly Androgen-Associated Autosomal Dominant Trait

In Australian Cattle Dogs (AUCDs), cystinuria was reported to be an autosomal dominant trait caused by a 6 bp deletion in the SLC3A1 gene (type II-A). Here we report an androgen association in this breed. A family of 11 adult AUCDs (five intact and one neutered male and five females) was genotyped for the SLC3A1 c.1095_1100del variant, and urine was examined for concentrations of cystine, ornithine, lysine, and arginine (COLA). Among this family, three males and five females tested heterozygous for the mutation, while all other AUCDs were homozygous for the wild-type allele. The two heterozygous intact males had severe COLA-uria, which decreased markedly after castration. Neither the third heterozygous male with a history of cystine calculi but already castrated nor the five heterozygous females exhibited increased COLA-uria. Heterozygosity for the 6 bp deletion in the SLC3A1 gene was associated with cystinuria in intact male AUCDs, but not in females. Castration of the heterozygous males reduced the cystinuria. Either the type II-A cystinuria in the AUCDs is an androgen-associated dominant trait, or this family also has another type III (androgen-dependent) cystinuria. Larger surveys are needed to further define the type(s) of cystinuria and effects of castration in AUCDs.