I successfully have treated the occasional hot spot by:
- washing the area thoroughly with green soap (a disinfecting soap from the drug store)
- rinsing the area well with cool water.
- Soak well with Sulfodene ( available in pet stores) applied with a cotton ball.
- Dry the area with a hair dryer on set cool or very low.
Repeat twice a day - and use bitter apple on the coat if needed. The hot spot should clear up in a couple of days.