Actual Diagnosis is usually made by a test known as a skin scraping. The veterinarian scrapes the skin, and then transfers the sample to a microscope slide and checked under the microscope for the mite. When an animal's immune system is healthy and functioning well the number of mites is kept in check but if the immune system is stressed or for some reason depressed mites can get out of control and symptoms of mange and hair loss will start to develop, usually around the eyes, ears, mouth, forelegs and sometimes the body. You will see Patches of red and crusty skin. A generalized form allowed to get out of control will have their entire body involved with hair loss and redness, and can develop a secondary bacterial infection and at that point the dog can become feverish. In any case you must improve you good friend's immune system and probably give a better diet. Above all please get to a vet with out delay to know if you are dealing with mites.