Well, nothing like trying to get some information to make oneself even more confused!
I'm not sure where everyone got the notion that I was planning to use peppermint EO - don't really like the stuff. My original post says spearmint.
I have looked at enough websites on EOs and animals that I have a splitting headache. Unfortunately, the majority of the sites address aromatherapy rather than preventing insect bites.
I keep coming across the same few EOs, though - cedarwood, eucalyptus, something called lemon eucalyptus (or eucalyptus lemon, depending on who you ask).
LavenderLady, I don't think I was clear that the amount of EOs I was considering would have an been an ounce per pound of the total blend, certainly not an ounce per pound of each individual EO. And as far as the eucalyptus, the friend that requested this had used some type of spray/shampoo for dogs that contained it.
Peppermint, the great thing about some of those sites is that too many of them contradict each other. I'm a bit wary of tea tree, as I've spoken to people whose dogs suddently developed a skin problem after prolonged use of a product containing tea tree oil.
WinterMoon, do you have any links to websites with the EPA information on it?
I'm acquainted with a lot of folks who use natural products on their dogs. I may ask around and see if any of those folks have any suggestions about EOs to use, or to avoid.
Thanks, everyone, for all your help. I'll soldier onward.
Anita