I have a Chihuahua who cleans her front legs a lot & then she has itchy moments where you'd think she has fleas. Can't find a flea. Whatever triggers her grows into itchiness. I have found a shampoo that is used to treat things like flea bite dermatitis, allergies, etc.. We use Tropiclean Oxi Med that we got from Petsmart. I gave her one bath in it & let it sit on her skin for about 8-10 minutes, rinsed her very thoroughly & she was good for a couple of weeks. We have no idea what triggers this in her. She's always funny about her front legs, clean, clean, clean but I notice she goes from licking to itching. We haven't figured out if it's a bug she encounters or a plant or weed that causes it. I flea comb her like I'm CSI hunting for crime evidence & thus far the Oxi Med is the only thing that stops it.