becareful if it's an open wound to keep it clean as to not cause a more severe infection.

Here are some links you can read more info about hot spots:
http://vetmedicine.about.com/library.../aa071300a.htm
http://www.osg.net/ttimes/pets/tt-pet30.html
http://www.canismajor.com/dog/hotspots.html
http://www.thepetcenter.com/exa/hotspots.html

You can buy hot spot relief spray from most pet stores, but, if it's already an open wound, I personally, would go to my vet first.