As defined in The American Heritage Dictionary Of The English Language, “Hypersensitivity or pathological reaction to environmental factors or substances, such as pollen, foods, dust, or microorganisms, in amounts that do not affect most people”this would include companion animals.
Allergies are the most challenging condition for a veterinary practitioner to attempt to treat, prevent and control due to their complexities. All tissues of the body are susceptible to substances causing the allergy problem, then there is the mode of entrance into the body, most importantly the multitude of substances in the environment(allergens) that are the initiators of allergies. For more years than I can recall, the treatment protocols involve the administration of steroids because of their anti-inflammatory effects, antihistamines, antibiotics, elimination diets, and anti-antigen injections often referred to as “allergy shots.” As the medications dissipate, the symptoms return and necessitates additional treatment, this is often repeated indefinitely because the cause has not been eliminated.
That which was just described is referred to as “symptomatic treatment”, not getting to the cause but merely making the patient more comfortable. The reason these patients are having the allergy problem is due to an immune deficiency. You don’t treat the allergy, you treat the immune system (immunotherapy). Continuous administration of drugs, like steroids, can be most harmful causing Cushing’s Syndrome that can result in death. The only “drawback,” to immunotherapy, is it requires time to “kick” in, about six weeks. If immunotherapy not be implemented the patient will always have allergy problems.