BusterAlert.org
Canine MDR1 Mutation
Info Center / MDR1Veterinary Fact Sheet

The multi-drug resistance gene (MDR1) encodes P-glycoprotein, a protein that functions as a drug-transport pump across cell membranes. A lack of P-glycoprotein means certain drugs cannot be absorbed, distributed or metabolized normally (particularly affecting the brain). Dogs with the MDR1 genetic mutation have a P-glycoprotein deficiency and are extremely susceptible to toxicosis from many common drugs.

Affected Breeds

The MDR1 mutation has been documented in many herding breeds and some sight hounds. The breeds affected by the MDR1 mutation (frequency %) is shown below.

Breed / Approximate Frequency
Australian Shepherd / 50%
Australian Shepherd, Mini / 50%
Border Collie / < 5%
Collie / 70%
English Shepherd / 15%
German Shepherd / 10%
Herding Breed Cross / 10%
Long-haired Whippet / 65%
McNab / 30%
Mixed Breed / 5%
Old English Sheepdog / 5%
Shetland Sheepdog / 15%
Silken Windhound / 30%

MDR1 Mutation Test

The Veterinary Clinical Pharmacology Laboratory (VCPL) at Washington State University has developed a commercially available test for the MDR1 mutation. Any dog of any breed can be tested via DNA collected from a cheek swab. Results are reported as homozygous for the normal MDR1 allele (normal/normal), heterozygous (mutant/normal), or homozygous for the mutant MDR1 allele (mutant/mutant). Dogs carrying the mutant gene or dogs from affected breeds that have not been tested for the mutation should not be given any of the MDR1problem drugs. Order a testing kit by contacting the Veterinary Clinical Pharmacology Laboratory at Washington State University: or by phone at 509-335-3745.

Problem Drugs

The most serious adverse drug reactions involve several antiparasitic agents (ivermectin, milbemycin, and related drugs), the over-the-counter antidiarrheal agent loperamide (Imodium), and several anticancer drugs (vincristine, doxorubicin, and others). These drug sensitivities result from a mutation in the multidrug resistance gene (MDR1 gene).

For the most up-to-date version of the MDR1 Problem Drug List, visit the WSU Problem Drug List website.

© 2012 MARS, Inc.

BusterAlert.org
Canine MDR1 Mutation
Info Center / MDR1 Problem Drugs List
with North American Brand & Trade Names

Dogs who test as having a mutated MDR1 gene OR dogs from affected breeds
who have not been tested for the mutation should avoid these drugs.

Drug names in bold are the generic drugs identified as problems by the MDR1 researchers. Below each generic drug is a list of some of the synonyms, brand,and trade names for the generic drug provided by BusterAlert.org. More drugs are likely to be added as MDR1 research progresses.

Drugs Affected by the MDR1 Gene Mutation

Acepromazine / Ivermectin / Loperamide / Paclitaxel
Ace / Abamectin / Acanol / Abraxane
Acepro / Acarexx / Acqta / Taxol
Aceproject / Advantage DUO / Anti-Diarrheal Formula / Onxol
Acevet / Avermectin / Cryoperacid / Ribampin
ACP / Bimectin / Deroser / Ricilin
Atravet / BMD/Ivomec / Diahalt / Rifaldin
PromAce / Ecomectin / Diamode / Rifamp
Butorphanol / Equell / Diarr-Eze / Selamectin
Dolorex / Equimax / Diarrhea Relief / Revolution Topical
Stadol / Equimectrin / Hurplex / Stronghold
Torbugesic / Eqvalan / Imodium / Vinblastine
Torbutrol / Heartgard / Imogen / Lemblastine
Torphajet / Ivercare / Imotil / Solbalstin
Doxorubicin / Ivercide / Imperim / Velban
Adriamycin / Iverhart / Kao-Paverin Caps / Velbe
Adriblastina / Iver-On / Lop / Vincrex
Caelyx / Iversol / Loperacap / Vintec
Doxil / Ivexterm / Nodiamex / Vincristine
Doxolem / Ivomec / Permidal / Citomid
Doxotec / Mectizan / Pramidal / Leurocristine
Hydroxydaunomycin / Megamectin / Raxamida / Oncovin
Hydroxydoxorubicin / Noromectin / Rediarin / Vinblax
Hydroxyldaunorubicin / Panomec / Top-Dal / Vincasar
Myocet / Phoenectin / Valfam / Vincrex
Rubex / Primectin / Milbemycin / Vintec
Erythromycin / Privermectin / Inteceptor / Vinorelbine
Abboticne / SparMectin / Sentinel / Navelbine
Aknin / Stromectol / Moxidectin
Aipimycin / Tri-Heart / Guardian Moxidectin
Erythrocin / Unimectrin / Proheart
Iliocin / Virbamec
Zimecterin

This list is not inclusive. For more information and updates on the Problem Drug List, see .

To find more generic and brand names of these drugs, see

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