Ask your veterinarian what he/she feels is necessary for your area.
Clip hair from area. Wash gently with pure soap and water or hydrogen peroxide. Cold water compress may stop milder bleeding.
For insect bites and stings, try to remove stinger with tweezers or a dab of cotton and apply a few drops of ammonia.
Clip hair form around the dime-sized spot, remove the scabs and paint the spots with tincture of iodine, 5% salicylic acid solution, or other fungicide 2 or 3 times weekly until recovery takes place. Make sure to apply to the surrounding area as well as its center, since spots tend to expand outward from center. Scabs, hair and debris removed from the dog should be burned to destroy the causative organism and prevent reinfection.