Dogs with a mutation in the MDR1 (multidrug resistance 1) gene may have severe and life-threatening reactions to some common drugs. Research has shown the mutation occurs more frequently in certain breeds. Approximately three of every four collies in the United States have the mutant MDR1 gene. The frequency is about the same in France […]
If you know whether the sire and dam have the mutant MDR1 gene, you can accurately predict if puppies in their litter will have the MDR1 genetic mutation. The chart below details breeding pair combinations and outcomes: