According to Pet Education.com, there are three types of mites that live on dogs. Two varieties, demodectic and sarcoptic mites, cause mange when left unchecked. Each affect your dog in different ways but all need to be diagnosed and treated with veterinary pharmaceuticals to be eliminated. If mites are suspected veterinary diagnostics include taking skin scrapings that can be examined under a microscope. Once the mite has been confirmed and identified, treatment can begin.
Mites make dogs itch. Intense scratching is typically the first symptom of a mite infestation. Dogs with mites don't just casually scratch. The scratching is persistent and often leads to further skin trauma and bacterial infections of the skin. Intense scratching is more often a symptom of a sarcoptic mite infestation. According to Holly Nash, DVM contributing veterinarian to Pet Education.com, dogs with sarcoptic mites tend to scratch more in warmer conditions when mites are present. She also notes that many dogs with mites are misdiagnosed with allergies based on the scratching of the skin. This is something of a two-edged sword. Your dog's allergies to the mite causes the itch, but the itch will not be resolved when treating for an allergic reaction unless you get rid of the mite.
Both sarcoptic and demodectic mites cause skin lesions in affected areas. The demodectic mite is often the culprit in young dogs or dogs with suppressed immune systems. Skin lesions range from raised pustules typically found on the face to generalized full-body scaly or greasy skin patches caused by mite infestations. The hair in these areas has a thin appearance, and the pigment beneath is often darker than healthy surrounding skin. Left untreated, the hair of infected dogs is very sparse, and skin on the entire body is scaly, compromised and full of a secondary bacterial infection.
Another symptom of a mite infestation is what appears to be dandruff. The rabbit fur mite, which can affect dogs, produces this odd symptom. Under a microscope this dandruff moves and is actually a mite. These mites tend to infest the area along the spine, causing the dog to scratch, have somewhat thickened skin and "walking dandruff."