Affected Breeds

Affected Breeds



Approximately three of every four Collies in the United States have the mutant MDR1 gene. The frequency is about the same in France and Australia, so it is likely that most Collies worldwide have the mutation. The MDR1 mutation has also been found in Shetland Sheepdogs (Shelties). Australian Shepherds, Old English Sheepdogs, English Shepherds, German Shepherds, Long-haired Whippets, Silken Windhounds, and a variety of mixed breed dogs.

The only way to know if an individual dog has the mutant MDR1 gene is to have the dog tested. As more dogs are tested, more breeds will probably be added to the list of affected breeds.

Breeds affected by the MDR1 mutation (frequency %)


BreedApproximate
Frequency
Australian ShepherdAustralian Shepherd50%
Australian Shepherd MiniAustralian Shepherd, Mini50%
Border CollieBorder Collie< 5%
CollieCollie70%
English ShepherdEnglish Shepherd15%
German ShepherdGerman Shepherd10%
Herding-Breed-CrossHerding Breed Cross10%
BreedApproximate
Frequency
Long-haired WhippetLong-haired Whippet65%
McNabMcNab30%
Mixed BreedMixed Breed5%
Old-English SheepdogOld English Sheepdog5%
Shetland SheepdogShetland Sheepdog15%
Silken WindhoundSilken Windhound30%