I use a product by Halo called cloud nine herbal dip. I've been using it for 3 years in Ohio and have not had any problems. I put it on my 3 cats and 1 dogs collars about once a month
I get mine at my doggie bakery in town but here is an amazon link
FYI: I bought 1 bottle 3 years ago and just had to get my 2nd
Amazon.com: Cloud Nine Herbal Dip: Kitchen &...
Marcy