The
English Shepherd
Pedigree Project
List of MDR1 results

A mutation in the canine multidrug resistance gene, MDR1, is associated with drug sensitivities in dogs related, even distantly, to collies. English Shepherds can have this mutant gene. Those dogs who carry two copies of the mutant gene are at most risk but dogs who only carry one copy are still at risk. There is more information at the bottom of this page, after the list of currently tested dogs.

English Shepherds were part of a study of the MDR1 gene done at University of California at Davis. Many of the dogs on the this list were tested as part of the study that ultimatley delveoped the test for the MDR1 gene.

If you are uncertain of your dog's MDR1 status you really should get them tested. The test can be done at home, is not painful (to the dog), and the $70 fee could save you hundreds of dollars and untold hours of worry. Consult your veterinarian and order a test kit from http://www.vetmed.wsu.edu/depts-VCPL/

MDR1 Genotyping Results

• Normal/Normal - These dogs do not carry the mutation, and will not pass on the mutation to their offspring. These dogs would not be expected to experience unexpected adverse drug reactions to normal doses of ivermectin, loperamide (Imodium(r)), and some anticancer drugs.
• Mutant/Mutant - These dogs carry the mutation and can not pass on a normal gene to their offspring. These dogs would be expected to experience toxicity after normal doses of loperamide (Imodium(r)), and some anticancer drugs, and high doses of ivermectin (greater than 50 micrograms per kilogram).
• Mutant/Normal - These dogs carry the mutation and may pass on the mutant gene to their offspring. These dogs may experience toxicity after normal doses of loperamide (Imodium(r)), and some anticancer drugs, and high doses of ivermectin (greater than 50 micrograms per kilogram).

• Ivermectin (Antiparasitic agent)
• Loperamide (Imodium(r); over-the-counter antidiarrheal agent)
• Doxorubicin (Anticancer agent)
• Vincristine (Anticancer agent)
• Vinblastine (Anticancer agent)