Atopic Dermatitis

Atopic Dermatitis, also known as atopy, is a form of skin disease. This disease not only affects people, but dogs, too. I, personally, have a dog that has this disease. There are not, essentially, any “cures” for atopy, but there are treatments and ways to control it. In this report you will learn about atopic dermatitis, the signs of the disease, and how to take care of it.

Atopic Dermatitis is a type of hypersensitivity characterized by an immediate physiological reaction. This includes movement of fluid from the blood vessels into the tissues, upon exposure to an allergen. Atopy occurs mainly in dogs with a tendency to allergic diseases. Atopic Dermatitis can be contrasted with the condition called delayed hypersensitivity, in which allergic symptoms take hours, or even days, to develop.

There has been found a genetic link between allergic reactions, IgE blood levels, bronchial hyperresponsiveness, and asthma which may exist on the 5q chromosome. IgE is an antibody involved in allergic reactions.

An allergy is when the immune system of mammals makes receptor proteins to foreign substances, each antibody being specific to a given substance. Antibodies are of several types, IgG, for instance, being involved in protection against viral diseases after vaccination, whereas IgE, involved in atopic dermatitis, is particularly concerned with protection against parasites. IgE antibodies coat mast cells in the skin where they sit waiting for contact with the parasite proteins to which the animal is sensitized. If the substance is encountered the mast cell releases chemicals which try to destroy the invader. In allergic reactions this whole system is oversensitive and the release of mast cell mediators in the skin occurs inappropriately to apparently innocuous substances such as pollens, molds, and house dust mites.

Signs of atopic dermatitis could include a rash, which starts within the first year of life, or dryness of the skin which can often lead to itchiness. Atopy usually is first apparent in the first two years of life. Other signs of atopic dermatitis could be that the dog grooms excessively, licking or chewing of the paws, abdomen, and perineum. The ears may be reddened and hot to the touch even thought the dog does not scratch at them. The result of this itchiness, also known as pruritis, is that the dog will often be brought to a vet in the first 18 months of life, but the itching may only seem like minor skin conditions at that time. Between episodes the skin may look remarkably normal. Spots, acute moist dermatitis, ear infections, and scratching may all seem to occur independently and only in retrospect the consistent pattern of the disease emerges.

Before any of these signs can become apparent, the dog must first be exposed to the allergen to which they can develop the abnormal immune response. Common sources of an allergy are house dust mites, pollens, or molds.

There is no definite test that will absolutely confirm a diagnosis of atopic dermatitis. Because of this, veterinary surgeons may suspect atopy after examining a patient, but must make sure that other causes for an itch are not present. Once other reasons have been ruled out, skin testing can be used to point out the allergies involved.

Other reasons a dog may scratch could be due to a flea infestation, (a dog may also have an allergy to fleas, so extreme flea killing measures must be taken,) lice, or sarcoptic mange. Although much less common, a food allergy may be the cause of the itching as well. All of these may mimic atopic dermatitis and should carefully be ruled out.

Skin testing is one of the ways to determine what allergen is the cause for the itching. In this process a small portion of the animals chest is shaved and, under sedation, small injections are made of the possible allergens. After 15-20 minutes the reaction should be present as to what allergen is causing the problem.

The process for diagnosing a pruritic dog is to first eliminate bacterial, yeast, and parasitic infections and infestations. If the itch persists a food trial is given with a completely new protein for a minimum of four weeks. If the itch persists a skin test is done to determine reactivity to house dust mites, pollens, and molds. But if the itch is dramatically reduced the dog is challenged with its old diet. If the pruritus returns a food allergy is diagnosed. If there is no response to the food a skin test is done.

Bacterial infections can make an animal itch far more and may even contribute to worsening the allergy. It should be treated promptly, using a combination of shampoos and antibiotics for a minimum of three weeks, and often longer.

Yeast infection is another complication. Spots are not seen in this disease, but instead, the organism causes redness, greasiness, and a mousey odor. Dogs can be quite depressed when infected and can be extremely itchy. Treatment is usually with baths containing enilconazole, or a combination of micronazole and chlorhexidine. Tablet therapy is also available, but as a surface infection, a yeast infection is best treated with bathing.

Similarly, fleas and other external parasites will make an atopic dog far more itchy. All allergic animals should have regular and efficient flea therapy using veterinary preparation to treat both the dog and the environment. With bacterial, yeast, and parasitic problems under control most dogs will be much more comfortable and some may only need minimal therapy using the least potent of the drugs available.

As you can see, atopy is not a pleasant disease, but it is treatable. The sooner atopic dermatitis is caught the more efficiently it can be treated. If you suspect your dog to have atopy you should take them to the vet immediately.