What is multidrug sensitivity? Some dogs and cats have a mutation in the MDR1 (multidrug resistance 1) gene also known as the ABCB1 gene, which plays an important role in limiting drug distribution to the brain and in enhancing the excretion of many drugs. Animals with the mutation may have severe adverse reactions – including […]
All heartworm products labeled for dogs in the United States have been tested in dogs with the MDR1 mutation as required by the FDA and have been found to be safe. Drugs such as ivermectin, selamectin, milbemycin, and moxidectin, are commonly used to treat and prevent parasites like heartworms. At low doses, such as those […]
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:
