Allergens are substances in the environment that cause the immune system to react as if invaded by a foreign body. If all dogs reacted to these substances, they would not be allergens, they would be toxins.
These allergens cause mast cells in the skin and basophils (specialized white blood cells) in the blood to release antibodies that contain histamines, serotonin, and leukotrienes. These antibodies are responsible for allergy symptoms.
Some inhalant allergies are seasonal. Dogs may be affected by inhaling grass pollen in spring and summer or ragweed pollen in late summer and early autumn. If this is the case, the dog will start to scratch and bite his body, lick his paws, shake his head, and rub his face along the carpet for relief from the itch when pollen grains are swirling in the air.
However, many dogs suffering from allergies itch somewhat year-round because they are also affected by household dust, mold spores, and other irritants.
Treatment for inhalant allergies ranges from keeping Lassie comfortable with cool baths in shampoos or rinses containing aloe vera, oatmeal, or eucalyptus to drug therapy to interrupt the itch cycle until the skin can be healed and the allergen has (hopefully) diminished.
Inclusion of Omega 3 and Omega 6 fatty acids in the diet can also help keep skin supple and healthy. Many dog food companies add these fatty acids to their premium foods. Supplements such as Missing Link provide not only the Omega oils but also a balance of vitamins and minerals necessary for good skin and coat health.
Environmental controls include frequent vacuuming and dusting of the areas where the dog spends time and keeping his bedding dust-free.
Some dogs may get relief from antihistamines such as diphenhydramine (Benadryl), clemastine (Tavist) or chlorapheniramine (Chlortrimetron), but owners should ask their veterinarian for proper dosage for their pet and may have to try more than one before finding the formula that helps.
Steroids such as prednisone interfere with the immune system function so that the body no longer considers the allergens to be invaders. Steroids should be used carefully and sparingly as they may cause liver problems and, in older dogs, can trigger a form of Cushing disease. Steroids also increase appetite and thirst, cause more frequent urination, and can increase aggression in some dogs. However, small doses of predisone can be invaluable in treating a dog with chronic or acute allergic reactions when all else fails.
Dogs with allergies can scratch and bite themselves into skin infections that need treatment with antibiotics. Prednisone is often prescribed for these dogs to get the itching under control while the antibiotic deals with the bacterial infection.
