Polycystic Kidney Disease is an autosomal dominant disease common in some lines of Bull Terriers (BTPKD). All cases of reported BTPKD to date in Australia descend from two affected half-siblings, making it very likely that there is only one disease-causing mutation in the Australian Bull Terrier population. Interestingly, these half-sibs were recently descended from an imported animal, suggesting the disease may well be international and due to this one mutation