MDR1 Gene Mutation and Drug Sensitivity in Collie Breeds

I have been reading up on potential drug sensitivity of collie breeds due to a mutation in the MDR1 gene, whatever that means. Basically, from what I gathered, a significant number of collies and collie-related breeds like the Australian shepherd (Romeo!) have a mutation in this gene, which makes them sensitive to many common drugs, including heartworm medication.

More information can be found at the following links:
Drug Sensitivity in Collies - very clear information about the mutation.
Buster Alert - not as clear, but good anecdotal information, as well as a drug list

You can order the test from Washington State and administer the test yourself, which costs about $50 less than if the vet were to do it. That's the route I'm taking with Romeo! For more information on that: http://www.vetmed.wsu.edu/depts-VCPL/

On a related note, here's an interesting article about how collies and sighthounds might be related due to research surrounding the MDR1 gene mutation: Collies have surprising relatives - Pet Health - MSNBC.com