Table 2.

Breed Distribution of the nt230(del4) MDR1 Mutation in Dogs Worldwide

Dog Breed	Range of Allelic Frequency (%) MDR1(-)	References
Collie	55 – 57	[57,61,76-79]
Longhaired Whippet	42	[57]
Shetland Sheepdog	7– 35	[57,61,76,77,80]
Miniature Australian Shepherd	20 – 26	[57,61]
Silken Windhound	18	[57]
McNab	17	[57]
Australian Shepherd	17 – 46	[57,61,76,77]
Wäller	17 – 19	[76,77]
White Swiss Shepherd	14	[76]
Old English Sheepdog	1 – 11	[57,61,76,80]
English Shepherd	7	[57]
German Shepherd	6	[61]
Border Collie	1 – 2	[61,76,77,80]
Herding-breed mix	6 – 7	[61,76]
Mixed breed	2 – 7	[61,76]

Note: Data from the referenced studies were included when at least 30 dogs were analysed per breed.