While I've been a little reluctant to continue this debate about parasiticides, I finally decided to share what I have managed to find out. I raised the issue with my daughter, who is a small animal veterinarian now working for the drug company Zoetis (maker of the flea/tick preventative Simparica). As dog owners know, a topical flea/tick treatment like K9 Advantix (which contains imidacloprid, a neonicotinoid) is applied directly to a small area of bare skin once a month. In contrast, a systemic treatment like Simparica is given orally in the form of a pill and circulates in the blood stream, so a parasite must take in a blood meal to be exposed to the active ingredient (which is not a neonicotinoid).
According to the Wikipedia article on neonicotinoids, laboratory studies have indicated that they have relatively low direct toxicity to birds and mammals and are less toxic compared to organophosphate and carbamate pesticides. The article concludes that the decline in bird populations in areas where neonicotinoids are used as pesticides is more likely due to the loss of food supply in insecting-eating birds. Also, an article in the July 2014 issue of the journal Nature concludes that there is a "high order of vertebrate safety" associated with neonicotinoids due to the different mechanisms of metabolism in vertebrates and invertebrates. Although my daughter was skeptical that much of the active ingredient would be present in a dog's hair, the Nature article mentions that "debris falling from treated animals" - which I assume would include hair and skin scales - "has been shown to be larvicidal to fleas in direct contact in the environment."
However, having said all of that, Gail is absolutely correct to raise concerns about the risks of neonicotinoids in the environment. It was been well-documented that they are toxic to bees and aquatic invertebrates, since they are water soluble and thus can be dispersed easily. So, if you are concerned about these environmental risks, as a general rule it would be wise to avoid neonicotinoid products. When it comes to dog and cat flea/tick preventatives, there are safer, non-neonicotinoid products available.
My dog is a Golden Retriever/collie mix, which means that she sheds A LOT. Last winter I collected several big handfuls of very fine, shed hair and put it in a plastic bucket outside, under the eaves of the house (mainly to keep my husband from finding it and throwing it away). My intent was to put it out in the spring to see if the birds would take it. However, when I went to check on it earlier this spring, I discovered that it was ALL gone. So, apparently it was a hot seller. I love the idea of putting dog hair in an old feeder, as was mentioned in the post on the WV listserv. (I have a peanut feeder which I'm not using, which I think would be perfect.) I will definitely try that the next time we have a major shed event. By the way, my dog has been on Simparica for fleas and ticks for several years (thanks to my daughter, of course). I can report that it is very effective and apparently does not pose the same kind of environmental risks as the neonicotinoids.
Elaine Hendricks
Greenbelt, MD