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Discussion Starter #1
I read on a rescue's page that NO collie type dogs (Sheltie, BC, Aussie, Rough/Smooth) should be given drugs containing Ivermectin. That the only heartworm med than can have is Interceptor.

While on a different site , (Washington State University), only 15% of Shelties tested are affected.

People on herding dog forums say they have given their Shelties Heartgaurd for years with no problems. So whats the truth? Can your vet give the test?

I'm just looking at all potential issues with next dog.
 

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I believe good breeders test for the MDR1 gene. If your dog is a rescue, though, better safe than sorry (unless you get your dog tested).
 

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You should poke around WSU's website. At the doses given for heartworm prevention, ivermectin is safe even for MDR1 mutants.

At higher doses used to treat certain types of mites, it is unsafe but at higher doses, ALL heartworm preventatives are unsafe for MDR1 mutants. Not sure why ivermectin keeps getting singled out in particular.
 

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Its simple enough to just buy a test kit honestly, my Aussie is a rescue, i had her tested(n/n) and i had Gem and Gyp tested even though the breeds in them have very very low incidents of it, everyone is convinced they are at least half Aussie(they are not to the best of my knowledge, Gem was a breeder surrender, Gyp was an owner surrender) i had them tested anyway just to be on the safe side, they are both n/n as well.
 

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Personal experience with MDR1... bought an australian shepherd puppy from a crap breeder. She was 6 months old, had ear mites... vet treated her with Ivermectin. She had a severe reaction, seized and ended up passing away.

Better safe than sorry to either TEST your dog, or just don't use the drug. There are alternatives.
 

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Personal experience with MDR1... bought an australian shepherd puppy from a crap breeder. She was 6 months old, had ear mites... vet treated her with Ivermectin. She had a severe reaction, seized and ended up passing away.

Better safe than sorry to either TEST your dog, or just don't use the drug. There are alternatives.
Again, the dose for mites and the dose for heartworm prevention are very different, and the dose for heartworm prevention IS safe for MDR1 dogs.

I don't personally care what drug anyone chooses to use, but don't make the decision based on fear-based misinformation!
 

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Discussion Starter #7
Personal experience with MDR1... bought an australian shepherd puppy from a crap breeder. She was 6 months old, had ear mites... vet treated her with Ivermectin. She had a severe reaction, seized and ended up passing away.

Better safe than sorry to either TEST your dog, or just don't use the drug. There are alternatives.
I will get mine tested. What are some alternatives? I've only ever used Iverhart.
 

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I will get mine tested. What are some alternatives? I've only ever used Iverhart.
The "alternative" drugs aren't really alternatives in one sense. For heartworm prevention, as Sass (who is actually a vet and I am not a vet) mentions, the main drugs all fall into the category of ones that are documented to have caused problems for MDR1 mutant dogs. The dosage is key; from WSU's information site:
Selamectin, milbemycin, and moxidectin (antaparasitic agents). Similar to ivermectin, these drugs are safe in dogs with the mutation if used for heartworm prevention at the manufacturer's recommended dose. Higher doses (generally 10-20 times higher than the heartworm prevention dose) have been documented to cause neurological toxicity in dogs with the MDR1 mutation.
Selamectin is in Revolution, milbemycin is in Sentinal and Trifexis and formerly Interecptor, and moxidectin is in Advantage Multi.

In addition to dosage of a given drug, the way I understand it is the using drugs concurrently or off-label and concurrent with other drugs in the "danger" classification can cause problems. For example, giving vet prescribed selamectin for hw prevention and then grabbing some ivermectin from the feed store to treat mites.

When I had a foster with demodectic mange, the vet prescribed ivermectin at way way higher dosages than is in any of the Heartgard/Iverhart etc type pills but the pup was very clearly a bully breed (the owner surrender said purebred apbt). I cannot recall the exact dosage, but it was basically more on a daily dose than the monthly amount is for heartworm prevention.

I would definitely go ahead and test if the dog has a decent potential of being one of the more affected breeds since aside from HW prevention, its important to know for many other drugs including ones used for surgical anesthetics for example (so, important to know before spay/neuter or in an emergency)
 

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I would get the dog tested. Its just a simple swab test and the results are fairly quick. Here is a link, the test cost about $70 and its worth every penny IMO. I try hard to avoid those drugs anyways even if the dog is normal normal. I am overly cautious with my dogs though. :) I do give Sentinel for heartworms (and like Shell said it has milbemycin which is one of the drugs on the list for possible reactions) because they are such a big deal around here, I have given heartguard plus before as well. The dose is so low that even mutant dogs tend to do fine with these doses when given correctly.

Its not just Ivermectin though, there are a lot of drugs.

Copied from Washington State University's website:

Drugs that have been documented to cause problems in dogs with the MDR1 mutation include:
Acepromazine (tranquilizer and pre-anesthetic agent). In dogs with the MDR1 mutation, acepromazine tends to cause more profound and prolonged sedation. We recommend reducing the dose by 25% in dogs heterozygous for the MDR1 mutation (mutant/normal) and by 30-50% in dogs homozygous for the MDR1 mutation (mutant/mutant).

Butorphanol (analgesic and pre-anesthetic agent). Similar to acepromazine, butorphanol tends to cause more profound and prolonged sedation in dogs with the MDR1 mutation.We recommend reducing the dose by 25% in dogs heterozygous for the MDR1 mutation (mutant/normal) and by 30-50% in dogs homozygous for the MDR1 mutation (mutant/mutant).

Emodepside (Profender�)-is a deworming drug approved for use in cats only in the U.S., but is approved for use in dogs in some other countries. Use of this drug in dogs with the MDR1 mutation has resulted in neurological toxicity.

Erythromycin. Erythromycin may cause neurological signs in dogs with the MDR1 mutation. A mutant/mutant collie exhibited signs of neurological toxicity after receiving erythromycin. After withdrawal of the drug, the dogs neurological signs resolved. There were no other potential causes of neurological toxicity identified in the dog.

Ivermectin (antiparasitic agent). While the dose of ivermectin used to prevent heartworm infection is SAFE in dogs with the mutation (6 micrograms per kilogram), higher doses, such as those used for treating mange (300-600 micrograms per kilogram) will cause neurological toxicity in dogs that are homozygous for the MDR1 mutation (mutant/mutant) and can cause toxicity in dogs that are heterozygous for the mutation (mutant/normal).

Loperamide (ImodiumTM; antidiarrheal agent). At doses used to treat diarrhea, this drug will cause neurological toxicity in dogs with the MDR1 mutation. This drug should be avoided in all dogs with the MDR1 mutation.

Selamectin, milbemycin, and moxidectin (antaparasitic agents). Similar to ivermectin, these drugs are safe in dogs with the mutation if used for heartworm prevention at the manufacturer's recommended dose. Higher doses (generally 10-20 times higher than the heartworm prevention dose) have been documented to cause neurological toxicity in dogs with the MDR1 mutation.

Vincristine, Vinblastine, Doxorubicin (chemotherapy agents). Based on some published and ongoing research, it appears that dogs with the MDR1 mutation are more sensitive to these drugs with regard to their likelihood of having an adverse drug reaction. Bone marrow suppression (decreased blood cell counts, particulary neutrophils) and GI toxicity (anorexia, vomiting, diarrhea) are more likely to occur at normal doses in dogs with the MDR1 mutation. To reduce the likelihood of severe toxicity in these dogs, MDR1 mutant/normal dogs should have their dose reduced by 25% while MDR1 mutant/mutant dogs should have their dose reduced by a full 50%. These patients should be closely monitored for adverse effects.

Drugs that are known to be pumped out of the brain by the protein that the MDR1 gene is responsible for producing but appear to be safely tolerated by dogs with the MDR1 mutation:

Cyclosporin (immunosuppressive agent). While we know that cyclosporin is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of cyclosporin for dogs with the MDR1 mutation, but we do recommend therapeutic drug monitoring.

Digoxin (cardiac drug). While we know that digoxin is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of digoxin for dogs with the MDR1 mutation, but do recommend therapeutic drug monitoring.

Doxycycline (antibacterial drug). While we know that doxycycline is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of doxycycline for dogs with the MDR1 mutation.

Drugs that may be pumped out by the protein that the MDR1 is responsible for producing, but appear to be safely tolerated by dogs with the MDR1 mutation:

Morphine, buprenorphine, fentanyl (opioid analgesics or pain medications). We suspect that these drugs are pumped by P-glycoprotein (the protein encoded by the MDR1 gene) in dogs because they have been reported to be pumped by P-glycoprotein in people, but we are not aware of any reports of toxicity caused by these drugs in dogs with the MDR1 mutation. We do not have specific dose recommendations for these drugs for dogs with the MDR1 mutation.

The following drugs have been reported to be pumped by P-glycoprotein (the protein encoded by the MDR1) in humans, but there is currently no data stating whether they are or are not pumped by canine P-glycoprotein. Therefore we suggest using caution when administering these drugs to dogs with the MDR1 mutation.
Domperidone
Etoposide
Mitoxantrone
Ondansetron
Paclitaxel
Rifampicin

There are many other drugs that have been shown to be pumped by human P-glycoprotein (the protein encoded by the MDR1 gene), but data is not yet available with regard to their effect in dogs with the MDR1 mutation.
 

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We have a "mini" aussie (or North American Shepherd), He is mutant/normal. We are lucky, our vet studied under Dr Mearly at WSU. From what she told our vet they have done extensive testing with Frontline Plus & Heartguard. Both are found SAFE for mutant/normal dogs. They DO NOT say the same for any other brands, even is said to be same doese. I guess there can be reactions & these two meds have been proven safe. We've used this combo for 5yr without issues.
 

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I would go ahead and have the dog tested. For the $70, it is peace of mind. My collie is mutant/mutant. I've had her on trifexis without incident and now we have switched to sentinal. As the list above, it's not just the hearworm meds to worry about. Immodium is a common home remedy that the dog can not get. It's better to know the status of the dog ahead of time.
 
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