Gensol's testing came back quickly (I mailed the swabs on Saturday, got the mail today. Fletcher is confirmed MDR1 -/-. It just confirms what the breeder already knew, the parents of my boy are negative. My rescue collie, however, is MDR1 +/-. Up to 70% of rough collies are. Since he is neutered, though, this is not that big of a deal. Just as a carrier, he could still react to large doses, so I need to let my vet know.