Atopy and Food Hypersensitivity
By Dr. Moore, Romberg, MacWilliam & Associates
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Atopy is a pruritic (itchy) dermatitis in which the animal develops and allergy (hypersensitivity) to environmental antigens (small proteins) which may be inhaled, ingested or absorbed via the skin. Common allergens are pollens, moulds, feathers, dust mites, fleas, wool and cotton. The affected animals have a hereditary predisposition to developing clinical signs of this disease, which include licking, scratching, rubbing, nibbling and chewing. The areas that are particularly affected are the paws, muzzle, ears and groin. This then results in hair loss, reddening and thickening of the skin. The continual irritation of the skin may result in acute moist dermatitis (pyotraumatic dermatitis), bacterial folliculitis and otitis external (ear inflammation and infections). In chronic cases the skin may become hyper-pigmented. Food hypersensitivity may result in the same signs as atopy as well as signs of gastro-intestinal disturbance (vomition and diarrhea).
Diagnosis of atopic dermatitis is based on clinical signs and tests which are performed on the animals’ blood and skin. Tests are performed on blood serum to identify which allergens are involved in causing the clinical signs. Skin biopsies and bacterial, fungal and yeast cultures may be taken to rule out other skin diseases.
The solution to allergic disease is the elimination of the offending allergens from the patients’ environment. However this ideal is seldom possible except where there is a food allergy and the specific foods are then avoided. The animal may be placed on a specific food which contains proteins it has not previously been exposed to. It is important that the animal eats only the recommended diet as feeding it other food may cause a reoccurrence of signs. A recent breakthrough in the treatment of food allergies in the manufacture of a food containing hydrolysed proteins. These proteins are so small that they do not trigger an allergic reaction by the body. The special dies must be used for at least six weeks before a response may be expected and may be used for the life of the pet if necessary.
Hyposensitisation of the patient is an alternative. This involves the subcutaneous injection of increasing concentrations of the offending allergens into the patient. The immune system is stimulated to produce allergen specific immunoglobulins, which bind to the invading allergen, preventing the interaction of the allergen, with sensitized mast cells, which release chemicals that induce the signs of atopy. Thus the specific allergen is eliminated prior to its interaction with the symptom-generating mast cells situated in the skin, intestinal tract and lungs. Hyposensitisation treatment occurs over a number of months with 70% of animals showing an improvement in clinical signs.
In many animals, several factors combine to cause itchiness. These include not only environmental allergens, but also allergens in food, parasites and bacterial and yeast infections. Eliminating some of these factors may decrease the animals’ itchiness. It may be necessary to use various shampoos on a regular basis to improve the patients’ skin hygiene in order to facilitate healing and the elimination of skin parasites, bacteria, fungi and yeasts.
Steroids (antiinflammatories) are very effective in alleviating the itch and are used at the lowest effective dose to decrease the risk of side effects. Antihistamines are often used in combination with steroids. Vitamin E and fatty acids (e.g. omega 3) may be required to assist the healing of the skin. Products applied topically to the skin (shampoos and creams) with anti-itch properties may also be of benefit.
Atopy and food hypersensitivities are recurrent, chronic ailments and long term medication is often necessary to control the clinical signs.
Diagnosis of atopic dermatitis is based on clinical signs and tests which are performed on the animals’ blood and skin. Tests are performed on blood serum to identify which allergens are involved in causing the clinical signs. Skin biopsies and bacterial, fungal and yeast cultures may be taken to rule out other skin diseases.
The solution to allergic disease is the elimination of the offending allergens from the patients’ environment. However this ideal is seldom possible except where there is a food allergy and the specific foods are then avoided. The animal may be placed on a specific food which contains proteins it has not previously been exposed to. It is important that the animal eats only the recommended diet as feeding it other food may cause a reoccurrence of signs. A recent breakthrough in the treatment of food allergies in the manufacture of a food containing hydrolysed proteins. These proteins are so small that they do not trigger an allergic reaction by the body. The special dies must be used for at least six weeks before a response may be expected and may be used for the life of the pet if necessary.
Hyposensitisation of the patient is an alternative. This involves the subcutaneous injection of increasing concentrations of the offending allergens into the patient. The immune system is stimulated to produce allergen specific immunoglobulins, which bind to the invading allergen, preventing the interaction of the allergen, with sensitized mast cells, which release chemicals that induce the signs of atopy. Thus the specific allergen is eliminated prior to its interaction with the symptom-generating mast cells situated in the skin, intestinal tract and lungs. Hyposensitisation treatment occurs over a number of months with 70% of animals showing an improvement in clinical signs.
In many animals, several factors combine to cause itchiness. These include not only environmental allergens, but also allergens in food, parasites and bacterial and yeast infections. Eliminating some of these factors may decrease the animals’ itchiness. It may be necessary to use various shampoos on a regular basis to improve the patients’ skin hygiene in order to facilitate healing and the elimination of skin parasites, bacteria, fungi and yeasts.
Steroids (antiinflammatories) are very effective in alleviating the itch and are used at the lowest effective dose to decrease the risk of side effects. Antihistamines are often used in combination with steroids. Vitamin E and fatty acids (e.g. omega 3) may be required to assist the healing of the skin. Products applied topically to the skin (shampoos and creams) with anti-itch properties may also be of benefit.
Atopy and food hypersensitivities are recurrent, chronic ailments and long term medication is often necessary to control the clinical signs.
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