Quest Plus

[JB]

Re the last article and the defective mice having high concentrations that crossed their blood-brain barrier: The same thing happens with ivermectin.

That same article talks about CF1 mice who are sensitive to ivermectin, and can be a problem especially with repeated doses. So for them, a double dose might well kill them. Or maybe multiple uses over time can kill them.

The point is - there ARE mammals who have defects that allow these chemicals, which are supposed to get to the brains of parasites but not cross the blood-brain barrier of vertebrates, to do so. Yes, ivermectin has killed the rare horse, and neurologically compromised the slightly less rare horse. Nobody talks about that though.

[kaya842]

Thank you all for the information! JB - something I just thought of - my grey mare (who has had Quest Plus previously without problem) was diagnosed with EPM in Nov. She was treated with levamisole and deqocinate (?) and passed her neuro exam in late February. Is there any reason the EPM May effect her reaction to Quest Plus? I am going to wait and ask the vet as well, though she has less experience with EPM than the other vet I use. I use this vet for routine things like teeth, shots and Coggins as she is better priced, does a good job, and we have a long standing relationship (which is good for our emergency calls/ needing meds dropped off).

[JB]

I would never use moxidectin on an EPM horse - the brain barrier is already compromised.

I’d use ivermectin with caution - you simply have to target bots.

[kaya842]

Good thing I asked. Bay mare will get Quest Plus and Grey (EPM) mare will get a fecal done and use ivermectin if necessary.
Are there any other dewormers that I need to watch out for besides the moxidectin? The anthelicide went over okay - I should have checked before I used it

[JB]

The macrocyclic lactones are the “worst”, with moxidectin being at the top. Ivermectin isn’t totall benign with EPM horses, so it’s a risk you have to weigh. Depending on where you live, maybe you only need to target bots once a year. BUT, if your area has high enough resistance issues with strongyles and both fenbendazole and pyrantel pamoate, you’re still left with ivermectin for those as well.

I honestly don’t know if preemptive banamine or something similar helps reduce the risk here - something to talk to your vet with. I don’t think I’ve ever looked into that.

[Scribbler]

With a healthy horse dosed once or twice a year with moxidectin without problems, would you ever worry about decreased tolerance over time?

[kaya842]

Thank you JB for all of your wonderful insight! I am consulting the vet now!

[JB]

@Scribbler

With a healthy horse dosed once or twice a year with moxidectin without problems, would you ever worry about decreased tolerance over time?

While I’d never say never, I have not heard of any decreased tolerance simply due to yearly use. I suspect any decreased tolerance issues are due to a compromised immune system that can come with age.

@kaya842

Thank you JB for all of your wonderful insight! I am consulting the vet now!

Glad you’re talking with him/her, let us know their thoughts