MDR1 Veterinary Fact Sheet
Download and print the MDR1 Problem Drug Info 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 MDR1 problem drugs. Order a testing kit by contacting the Veterinary Clinical Pharmacology Laboratory at Washington State University: https://vcpl.vetmed.wsu.edu/ 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).
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 |
|
|
To find more generic and brand names of these drugs, see https://www.igenericdrugs.com/