MDR-1 Mutation (September 2007)
Linda Aronson, DVM

You will remember that at the BCCA specialty last year Beardies were tested for the MDR-1 mutation.  This is common in collies (rough and smooth), Australian Shepherds and several other breeds and renders them hypersensitive to certain drugs, most notably ivermectin, causing neurological symptoms.  This is because these drugs are able to cross the so-called blood brain barrier and gain access to the Central Nervous System, which is most often protected to some extent from drugs and toxins in the general circulation.

I am happy to report that cheek swabs were collected from 97 Beardies.   None of these showed the MDR-1 mutation.  One sample was rejected because of insufficient cells on the sample.   Given the size of the sample taken it seems unlikely that the MDR-1 mutation occurs in Bearded Collies.  However, we do know that certain drugs can trigger autoimmune disease in our breed as well as many others with genetic susceptibility.  One of the most commonly implicated drugs is ivermectin, so we do need to maintain our caution in using this and other drugs in our dogs.

I’d like to thank everyone who participated and added to our knowledge of our breed’s health.  I would like to particularly thank Jane Cooper for organizing the project, collecting most of the samples and liaising with Dr. Katrina Mealey’s laboratory at Washington State University.  Dr.  Mealey very generously offered to run these tests – normally costing $40 per test – for free, and we are very grateful to her also.   

Linda Aronson, DVM
Chair, Health Committee