A hot spot is where the skin becomes irratated and the dog chews the hair right out of the skin. It will then appear red and scabby. It will itch and bother your dog. You can either take your dog to the vet or myself, I administer some gold Bond Powder. It will dry the hot spot right up. Most hot spots occure on Collies from moister laying on thier skin in humid weather. One thing about my breed is that if they get a bath in hot humid weather it is imparative to completely dry them. Most long hair dogs will be effected this way from moisture.

Hope I explained this well enough for you.

http://www.thepetcenter.com/exa/hotspots.html