My 13 lb Westie/Maltese/Toy Amer Esk? 9 yr old dog began feverishly biting at her inside hind legs & paws summer ‘18. She lost her buddy (dog) mos prior. Stress? Likely environmental or diet per vet. Normally eats Blue Buffalo Wilderness chicken & nvr had a prob. I got a good deal on grain free Rachel Ray food last summer & only gave her some for a few wks. She’s a belly rubbing addict when happy & looks like a seal. Lots of factors. SHE LOVES THIS FOOD! (It almost worries me). Haha. I’ve nvr seen her not poke around at her food & make a mess. Granted, she is on 1.2mg Steroid pill for about 10-14 days. It took a cpl of days for her biting at herself to stop. Btw, her belly was also getting blacker w/ dots since summer. Vet said her biting at skin causes extra melanin to area. I had tried GNC antifungal & antibacterial shampoo & many applications of antifungal cream on her belly. Vet said it wasn’t harmful. Google states black dots are from fungal. Don’t trust google! I’ll post an update later on.