CANINE ALLERGY What is an allergy? An allergy is a state of over-reactivity or hypersensitivity of the immune system to a particular substance called an allergen. Most allergens are proteins. The allergen protein may be of insect, plant or animal origin. Initial exposure of the dog, or more likely multiple exposures, to the allergen may over-sensitize the immune system, such that a subsequent exposure to the same or related allergen causes an over-reaction. This means that the immune response, which normally protects the dog against infection and disease, can actually be harmful to the body. The immune reactions involved in allergies are quite complex. Most reactions involve an antibody in the blood called Immunoglobulin E (IgE). In an allergic reaction the allergen protein molecules combine with IgE antibody molecules and attach to a type of cell called mast cells, found in many tissues throughout the body. When these cells are attached to the allergen, they break up and release potent chemicals such as histamines that cause local inflammation (redness, swelling and itching). This inflammation causes the various signs associated with an allergic reaction. What are the symptoms of allergies in dogs? The most common symptom associated with allergies is itching of the skin, either localized (in one area) or generalized (all over the body). Another group of symptoms involves the respiratory system with coughing, sneezing, and/or wheezing. Sometimes, there may be runny discharge from eyes or nose. The third manifestation involves the digestive system resulting in vomiting and diarrhea. How common are allergies in dogs? Unfortunately, allergies are quite common in dogs of all breeds and backgrounds. Most allergies appear after the pet is six months of age with the majority of affected dogs over age two. Are allergies inherited? Some allergies are inherited. The inherited trait is known as Atopy (see What is Inhalant Allergy or Atopy below). What are the common allergy-causing substances (allergens)? A very large number of substances can act as allergens. Most are proteins of insect, plant or animal origin, but small chemical molecules known as haptens can also cause allergy. Examples of common allergens are pollens, mold spores, dust mites, shed skin cells (similar to "pet allergies" in humans), insect proteins such as flea saliva, and some medications. What are the different types of allergy? There are several ways of classifying allergies. Some examples of classifications include: · Precipitating allergen - Flea Allergy Route the allergen takes into the body - Inhalant Allergy, Skin Contact Allergy or Food Allergy Time it takes for the immune reaction - Immediate-type Hypersensitivity, also called Anaphylaxis or Shock and Delayed-type Hypersensitivity · Type of immune reaction - Types I through IV Hypersensitivity · Clinical Signs - Allergic Dermatitis or Allergic Bronchitis · Inherited forms - Atopy or Seasonal Allergies What is Contact Allergy? Contact allergy is the least common type of allergy in dogs. It results from direct contact to allergens contained in flea collars, chemicals in the lawn or the grasses themselves and bedding, such as pyrethrins or wool. If the dog is allergic to these substances, there will be skin irritation and itching at the points of contact, usually the feet and stomach. Removal of the allergen (once it can be identified) often solves the problem. What is Flea or Insect Bite Allergy and how is it treated? Flea allergy is the exaggerated inflammatory response to a flea bite or other biting insect. Flea saliva is the most common allergen. It is a common allergy of dogs, although only a minority of dogs becomes allergic. Most dogs experience minor irritation from flea bites. The flea or insect bite allergic dog will react to a single bite with severe local itching. It will bite and scratch itself and may remove large amounts of hair, especially in the tail-base region. Secondary bacterial infection may occur in the broken skin. The area most commonly involved is over the rump in the tail-base region and the hind limbs. Because one flea can be a problem for the allergic dog, strict flea control is essential. This is difficult considering the life-cycle of fleas, but with modern medications and home treatment options, you should be able to provide a flea-bite free environment for your dog. Your veterinarian can give you tips on protecting your dog from fleas. When strict flea control is not possible or in cases of severe itching, anti-histamines or corticosteroids (steroids) can be used, under careful veterinary guidance, to block the allergic reaction and give relief. If secondary bacterial infection is present, appropriate antibiotics will be prescribed.
Posted on: Wed, 17 Jul 2013 12:26:21 +0000
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