A hot spot is actually a skin infection which is located on the surface of the skin. It spreads rapidly and is very irritating. There are a few different causes of hot spots. They can appear after two dogs have been aggressively playing and biting each other. This playing breaks down the skin and the bacteria from the mouth gets into the abrasion.
Hot spots can appear after serious bug bits such as with flies or bee stings.
In most dogs, hot spots are a result of allergies. When dogs breathe in pollens, molds, or other things they have become allergic to, they do not get asthma and irritated sinuses. Rather, they get skin irritation. One of the most common skin conditions caused by allergies is the hot spot. That is why some breeds get lots of hot spots, especially the golden retriever.