What can u do for heat spots ,treatment and prevention

Hotspots usually develop when something irritates the dog's skin. It could be a flea or tick bite, an allergy, etc.--anything that causes the dog to start licking and digging at the area. This gets the area more inflamed and infected and causes a runny nasty sore, literally overnight.
Best to have the vet treat them, and try to help you figure out what the underlying problem is. If the dog is prone to getting them, the vet will usually send you medication home to use when you first see one starting up.