Approximately 30 percent of our pet population has some allergy. Most of the time, it is just an occasional discomfort, but for some it will require a trip to your veterinarian.
Allergies are triggered by many different things, and can be grouped into three general categories: parasites, inhalants, and certain “contact allergens.”
The easiest to diagnose are flea-bite allergies. Diagnosis is made when fleas or their eggs (“flea dirt”) are found in the hairs of your pet. Dogs who are not flea-bite sensitive will occasionally scratch or bite at themselves. They do not traumatize their skin. On the other hand, a dog with allergic flea bite dermatitis can have only one flea—or in some cases, none—but even former bites leave in their wake an excoriated, ulcerated, inflamed, infected skin. Today, with a combination of oral and topical flea products, the infestation can be controlled. Most of the monthly topical products will kill fleas during the first two weeks before a flea can bite, and in the second half of the month, within 24 hours of infestation. The remaining infection can be treated with appropriate antibiotics and steroids.
Inhalant allergies are grouped into three major categories: molds, pollens, and dust. Mold and dust are present throughout the year, but depending on your location, pollen may be seasonal. In the upper Midwest, for instance, the pollen season will usually start in April with tree pollen, followed in May by grass pollen, and in August, with ragweed. The combined force of all three groups can cause allergic animals to have many problems during the pollen season. Animals usually manifest allergies by skin break-outs. These are often called “summer itch” or “hot spots.” Often, pet owners experience allergy symptoms at the same time as their animal friends. Their symptoms are usually different, however. Humans have more mast cells in the lungs and upper respiratory tract, while dogs have more mast cell distributed in their skin. Therefore, the target organ and symptom is different, but the allergic reaction is identical.
Owners should be aware of allergy problems early on and not wait for it to get better. The longer it progresses, the longer it takes for the allergic reaction to clear. Aggressive treatment with anti-inflammatory agents—and antibiotics if necessary—should be pursued.
Shampoos, conditioners, and other substances can cause what we call contact dermatitis. I rarely treat my patients with shampoos or other products, especially when they are in the acute phase of a breakout. Their skin may overreact to everything at this time, and the goal is to reduce or avoid further allergic reaction. I usually recommend that only water be used to bathe the dog during the initial phase of treatment. Bathing with shampoos not only increases the risk of allergic reaction, but also washes away nature’s attempt to produce antibacterial protectants on the skin.
Allergy testing and desensitization may follow a successful allergy treatment program. In my own practice, I describe the initial breakout in terms of a fire. If the fire is burning, you don’t call the fire prevention department, you call the hook-and-ladder. In this case, that means steroids and antibiotics. Allergy testing, or fire prevention, is reserved for the recurring cases that pop up within three to four weeks after treatment stops.
Allergy testing consists of either drawing blood and performing an in-vitro test performed or conducting skin tests. The new blood tests may be helpful in diagnosing some allergies, but they have not yet been as reliable as the intradermal skin test. In the intradermal skin test, a small amount of a purified diluted material, such as dust, is injected into the dermis. This is done with between 20 and 75 antigens. The injected material is allowed 15 minutes to react. A weal/flare reaction will occur from those antigens to which the animal is sensitive. These reactions are graded I to IV, and depending on how large and red they are.
Based on the results of the testing, allergenic extracts are prepared. These extracts start at a high dilution and gradually increase in concentration. The goal of the immunotherapy is to create IgG antibodies, which I like to call the “good guys,” because they will hopefully get to the offending antigen before the IgE antibodies do. IgE antibodies mediate the allergic reaction. Additionally, it has been discovered that immunotherapy stimulates the “helper-suppresser” T cells, which help shut down the production of IgE.
The good news is, the future is bright for the allergic pet. Many new classes of drugs are being developed and a Monoclonal antibody against IgE will soon be available, allowing quicker results with fewer injections.