Yikes!
While my pure-bread Ausie black-tri was alive, I had him on IverHart Max (ivermectin / pyrantel pamoate / praziquantel). Never had a problem while he was alive (lived to 17!).
I have since adopted another dog that had been picked up as a stray, so the lineage is unknown. The adoption counselor thought he might be a Catahoula Leopard Dog, or a mix. He has the blue merle gene. I’ve had him on Iverhard Max as well this summer. So far, no problem, but with an unknown breed, which obviously shares a gene with other breeds which are sensitive to ivermectin, I’m now concerned.
Should I proceed with a MDR1 test?
Here’s some pictures of him:
https://secure.flickr.com/photos/michael-litscher/sets/72157622814251321/