I when to a natural grocery store and brought my dog a natural flea collar
and put it on my small dog when I got home. Within half a hour I had a headache and my poor was feeling sorry for himself . I read the box to see what kind of oils where in the collar and pennyroyal oil was one of them .
I looked this up and found out it's not safe to uses on pets and that is can give you bad headaches. We really have to be careful with natural ingredients , being natural does not mean it safe for our pets or for people. I was surprised the owner of the store did not check out the company before selling their pet products as she opened to store so people would have a place to buy safe food and pet products.