A good portion of collies (like 3 out of 4) and
alot of other herding breeds or dogs with collie in them can have a mutant gene
called an MDR-1 that can cause them to have a reaction to ivermectin and several
other drugs. I had 6 of my collies tested and 4 are normal/normal, 2 are
mutant/normal. (5 of the collies are family members, the 6th is related who is
one of the m/n dogs.) Good to know for me, though I still would not use any drug
with ivermectin in it on them. Being a breeder/fancier, I have seen and heard
too many horror stories. Here is a website for anyone interested in reading
more, especially if they have a dog who they think might carry the mutant gene.
It's http://www.mdr1test.com.
