DNA test - MDR1
Multiple Drug Sensitivity
Multiple Drug Sensitivity (MDR) is an inherited condition that makes affected dogs particularly sensitive to drugs like ivermectin and loperamide. In normal dogs the blood/brain barrier protects the brain cells from various drugs and toxins and central to this is a protein called P-glycoprotein which physically pumps drugs and toxins from the cerebrospinal fluid back into the blood circulation. The MDR-1 mutation results in an inactive P-glycoprotein which means that drugs and toxins can accumulate in the cerebrospinal fluid and begin to inhibit brain activity. The result is that exposure of affected dogs to such drugs may be an illness requiring an extended hospital stay - or even death. The MDR-1 mutation is a recessive mutation.
Source of DNA Test: http://www.thekennelclub.org.uk/download/8288/dnatestsworldwide.pdf