Yes Dog hot spots can happen by the hair matting & preventing the skin from getting fresh air. It is also important to note that sometimes pain can cause hot spots too.
Dogs usually lick and bite a matted area that is painful , and the constant licking and biting can eventually result in a hot spot.
Hot spots are basically circular patches on the dog's skin that occur when the dog's natural bacteria over-populate in the area, usually because the dog's immune system is not a hundred percent up to par.
Sometimes, however, skin problems that look like hot spots are in fact something else.
For example, some fungal diseases and even some type of cancer start out looking like a hot spot.
It is therefore important to get a proper diagnosis to make sure that the problem is actually hot spots and not something more serious.