Updated November 28, 2020
Recently I’ve seen two Australian Shepherd puppies sold with a list of 52 drugs to avoid. I understand the intention, but this list is incorrect and alarmist. It contains many perfectly safe drugs, some of which will be essential later in life.
Yet who would use them after reading this:
Not every Australian Shepherd will have a negative or deadly reaction to the drugs listed above. However enough of them have had severe reactions and/or died to warrant caution. YOU must be an advocate for your Australian Shepherd.source: Do Not Use Drugs For Australian Shepherds.
Despite having many safe drugs, the list of 52 has also missed a few that may be toxic. So here’s your guide to which drugs to avoid in dogs with the MDR1 mutation.
What Is MDR1 Multi Drug Resistance?
The MDR1 gene codes for P-glycoprotein, a cellular pump responsible for the transport of certain chemicals. Mutations in this gene cause faults or delays in the removal of some drugs from cells. This is most evident in the brain.
Dogs with the MDR1 mutation are at risk of serious drug toxicities at doses that are safe to other dogs. In some cases these can even lead to death.
Which Breeds Are Affected?
The following list shows the common dog breeds most likely to have the MDR1 mutation, and the percentage affected in each.
|Breed||% source1||% source2|
|White Swiss Shepherd||–||15|
|Herding Breed (cross)||10||–|
|Old English Sheepdog||5||8|
|Australian Cattle Dog||–||3|
It’s possible, though unlikely, for any dog to carry the mutation (rarer breeds can be found at both sources). Importantly, if you have a high-risk breed, or just want to be sure, you can easily get your dog tested at your local vet. It’s worth it!
MDR1 Drug List: Safe vs Avoid
The following drugs may have delayed transport in dogs with the MDR1 mutation. Some remain safe, others should be avoided.
|Moxidectin||Heartworm||Safe at regular doses|
|Selamectin||Heartworm||Safe at regular doses|
|Milbemycin||Heartworm||Safe at regular doses|
|Spinosad||Fleas||Avoid unless alone|
|Emodepside||Worms||Avoid (rarely used)|
|Acepromazine||Sedation||Reduce or don’t use|
|Butorphanol||Sedation/Pain||Reduce or don’t use|
|Apomorphine||Induce vomiting||Reduce or don’t use|
|Morphine||Pain||Use with caution2|
|Buprenorphine||Pain||Use with caution2|
|Fentanyl||Pain||Use with caution2|
|Cyclosporin||Immune system||Monitor drug levels|
|Doxycycline||Antibiotic||Safe at regular doses|
|Erythromycin||Antibiotic||Avoid (rarely used)|
|Digoxin||Heart disease||Monitor drug levels|
|[many drugs]||Chemotherapy||Check all before use3|
|Loperamide||Diarrhoea||Do not use|
|Ondansetron||Treat vomiting||Use with caution|
- Ivermectin is reported safe at heartworm prevention doses but there are better drugs available
- Opioid pain relievers are essential drugs, and appear safe if used with care
- Many cancer chemotherapy drugs can cause severe or fatal toxicity
These are likely to be the only common drugs your dog may encounter but we cannot guarantee accuracy as our knowledge is incomplete. If you have any specific questions, feel free to leave a comment below or ask your vet.
Related: Brand names of the common heartworm and flea products that contain the drugs mentioned
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!
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