Re: The reason for the Ivermectin-sensitive Collie – A deadly gene defect

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just thought i would add to this the stuff that i have recieved this morning: i know much this info was in the previous links but not all can get links to work and there are some slight changes/additions  🙂

It is now well known that collies and related breeds can have adverse reactions to drugs such as ivermectin, loperamide (imodium), and others – the problem is due to a mutation in the multi-drug resistance gene coded MDR1-  this gene encodes a protein called P-glycoprotein – this acts as a toxin releasing protein that removes many drugs and other toxins from the brain – the dogs that carry the MDR1 cannot get rid of thiese toxins and some drugs out of the brain as a dog not carrying the gene would – this results in illness requiring an extended hospital stay or even death.

it is now believed that approximately 3 of every 4 collies worldwide have the mutation – – the MDR1 mutation has also been found in setland sheepdogs (shelties) – australian shepherds, old english seepdogs, german shepherds, long-haired whippets, silken windhounds and dogs that have these breeds as crosses

Problem Drugs

There are  now many different types of drugs that have been reported to cause problems in collies, ranging from over-the-counter antidiarrheal agents like imodium to antiparasitic and chemotherapy agents. It is likely this list will grow to include more drugs as research progresses.

Drugs that we are now aware of that or are strongly suspected to cause problems in dogs with the  MDR1 mutation are:

Ivermectin (antiparasitic agent)
Loperamide (Imodium®; over-the-counter antidiarrheal agent)
Doxorubicin (anticancer agent)
Vincristine (anticancer agent)
Vinblastine (anticancer agent)
Cyclosporin (immunosuppressive agent)
Digoxin (heart drug)
Acepromazine (tranquilizer)
Butorphanol (pain control)
Fentanyl (pain control)
Meperidine (pain control)

Potential Problem Drugs

the following drugs may potentially cause problems when given to dogs that have the mutation – these are still being studied but the results coming in are alarming – in all we are expecting a final result of over 50 different drugs.


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