I found this for you. Hope it helps. You may want to go to that page. It has lots of info on paws.
Yeast infections may be diagnosed by the evaluation of skin smears taken of the paw.
This condition is treated by the use of antifungal medications. PAW CONDITIONS IN DOGS and links to some of the top Grooming & Clipping articles and tips on the net! Clipping Your Dog's Nails!