P-glycoprotein is a protein found in all mammals that serves as a “gate keeper” to keep drugs from concentrating in the brain, kidneys, gastrointestinal tract and other organs. Without this protein which is encoded by the MDR-1 gene (also known in dogs as the ABCB1 gene) the pet would become “toxic” from certain drugs. Research into this was done by Dr. Katrina Mealey at Washington State University which found that certain dog and cat breeds may be deficient in this gene which “detoxifies” drugs. Dog breeds or mixes thereof that can be affected include herding breeds, White German Shepherds, Collies, Australian Shepherds and many other breeds. Cats can be affected as well. Some drugs that cause problems mostly neurologic (including coma), are erythromycin, ivermectin at higher than prescribed doses, chemotherapy including doxorubicin and vincristine, the sedative-acepromazine, and OTC loperamide (Imodium). The list of drugs increases with time! You can have your pet checked for a nominal charge via a mail in cheek swab DNA test at Washington University by emailing: vcpl.vetmed.wsu.edu