Dermatitis, which refers to any inflammation of the skin, is a very frustrating condition for dogs and their owners, because it can be caused by so many different things and can contribute to so many different clinical signs. Dermatitis itself is not particularly difficult to diagnose, because the symptoms of skin inflammation are rather obvious. However, the underlying cause of the condition can be tricky to figure out. When a dog presents with a history of intense skin itchiness and scratching, and accompanying raw, weeping skin sores, the veterinarian will begin a systematic hunt to determine the cause of the condition. This diagnostic challenge normally begins with a thorough physical examination and history. The veterinarian will look for external factors, such as parasites and any identifiable environmental allergies. Flea bites can cause horrible dermatitis in dogs, and mange from mites can cause equally significant skin problems. The attending veterinarian will ask the owner lots of questions about the dog’s health history, travel history and diet. She will carefully examine the dog’s skin and hair coat. She may also do a skin scraping to help identify any parasites that have burroughed deep into the hair follicles. This is the best way to diagnose demodectic mange.
If no obvious cause of skin inflammation is found during the initial history and physical examination, the search will go on. Blood and urine samples can be taken to help to rule out systemic causes of dermatitis, such as hyperadrenocorticism (Cushing’s Disease), diabetes, kidney disease or hypothyroidism. If the results of routine blood and urine tests are normal, the veterinarian probably will next focus on possible causes of hypersensitivity (allergic) reactions that commonly contribute to skin inflammation. Dietary changes, including an elimination diet protocol, may be recommended to determine whether the dog has allergies to particular food ingredients. This involves feeding the dog only a few ingredients at first, such as rice and boiled chicken, and then gradually adding one more ingredient at a time, assessing the dog’s skin reaction along the way. Elimination diet trials take a long time and lots of patience on the part of the owner, and the dog. Skin biopsies may be taken in resistant cases, although this is not usually necessary and rarely done to diagnose skin problems in dogs.
Sometimes, the underlying cause of canine dermatitis will never be discovered. In those cases, prescription oral and topical medications and shampoos may be used to help reduce the severity of the symptoms. If left untreated, dermatitis can cause so much discomfort that the dog scratches, bites and digs at its skin, causing self-trauma and weeping wounds that are ripe sites for secondary bacterial skin infections. If your pet shows signs of skin problems, make an appointment with your veterinarian as soon as possible.