Immunotherapy has been the buzzword these days especially with the recent breakthroughs in human cancer therapy. In actuality, the concept and some applications of immunotherapy have been around for a couple hundred years like vaccines, as the definition indicates:
“A type of biological therapy that uses substances to stimulate or suppress the immune system to help the body fight infection and diseases. Some types of immunotherapy only target certain cells of the immune system. Others affect the immune system in a general way.”
Recent immunotherapy dialog has focused on treatment options for sensitivities (allergies) and cancer in humans and pets. We’ll discuss cancer immunotherapies in another article.
Often I write about food sensitivities or intolerances, which are relatively common and generally mild to moderate chronic responses that occur when a body reacts by producing IgA and/or IgM antibodies to a particular food or ingredient. These reactions typically occur on mucosal surfaces and are expressed in body fluids like saliva, sweat, tears, feces and urogenital secretions. Food sensitivities are very common intolerances and are frequently loosely referred to as “allergies.” However, a true food allergy is rare and causes more immediate hypersensitivity reactions such as acute anaphylactic shock or sub-acute immune responses.
You have probably heard a lot about food immunotherapy in humans these days, which gradually exposes a patient to increasing doses of the known or suspected offending food in the hopes that the body will be able to develop a tolerance to it. This is a fairly new and controversial method aimed to desensitize patients. We do not know if these therapies will cause a body to achieve permanent, temporary, or no tolerance to the offending food, as each patient responds based upon his genetic (nutrigenomic) background which is highly individualized. Inherently, the food exposure during treatment could cause an unwanted side effect such as a reaction you are attempting to avoid. At the present time, food desensitization via immunotherapy is not recommended by veterinarians for dogs or cats and is not available on the market. We opt for the more traditional protocol of diagnosis
Environmental or seasonal allergens (antigens) – such as molds, grasses, trees, ragweed, pollens, fleas, yeast, fungi, dust mites, etc. – cause other types of antibodies, namely IgE, IgG and IgD to be elicited and the body responds by releasing histamine. Now, many veterinary and medical professionals will likely say, “We are all allergic to these antigens to some degree.” This is true. When the reaction is extremely severe to environmental inhalant or contact allergens, atopic dermatitis could result, which is a chronic inflammatory condition that causes extreme itchiness, skin eruptions, redness, and possibly hair loss.
Several veterinarians will say this is a progressive condition, meaning it becomes worse over time. This is often true depending on the antigen. One year the pollen count may be high, but another year it could be low. Thus, your pet’s reaction will vary. As well, if you move to a different climate, the body may need to acclimate to the new weather and ambient conditions. Dust mites, molds, fungi and yeast are particularly troublesome since they are present year round.
Diagnosing atopic dermatitis is either by specific serum or intradermal skin testing or by a process of elimination. We first need to rule out the presence of demodectic mange (prevalent skin mites), fleas, Malazzesia (yeast; fur mite; walking dandruff), scabies, food sensitivities and other conditions. In fact, food sensitivities are often concurrent with these environmental allergies. So, if a pet parent eliminates the offending food(s), the environmental component may be easier to manage. For diagnostic evaluation, veterinarians can order a serum allergy blood test panel or intradermal skin prick test to determine what is causing the atopic dermatitis. However, as my colleague, Dr. Ian Spiegel, points out, “A simple blood or skin test is not sufficient because clinically normal animals may also have positive findings on these tests. All results must be interpreted in the context of each individual case.”
There is no real cure for atopic dermatitis, we only have management options to alleviate the symptoms such as: avoiding the offending antigen (this can be difficult), wiping down your pet after walks with a green or black tea or dilute chlorhexidine solution, if it is a reaction to an outdoor allergen; shampoos; topical steroid creams and lotions; oral corticosteroids; antihistamines; and omega-3 fatty acid supplementation. As many of you know, I prefer to avoid oral or systemic corticosteroids as much as possible. Initial therapy with steroid/antihistamine products is often helpful or needed to calm the initial reaction. Newer therapy can include oclacitinib (Apoquel) for stubborn or resistant cases.
Another option is allergen-specific immunotherapy, which is considered the gold standard for atopic dermatitis management. Similar to food immunotherapy for humans, we gradually increase the dosage amount of the specific antigen(s) causing the problem until the tolerance threshold has been achieved. At the present time, immunotherapy for environmental antigens can be administered via injectable shots (Allergen-Specific Immunotherapy; ASIT) or a newer treatment option that puts a few drops under the tongue (Sublingual Immunotherapy; SLIT).
ASIT and SLIT are specifically tailored to the individual pet. For instance, if you were to walk into the laboratory mixing these formulations, you will notice that none of them are alike.
If the treatment is successful, veterinarians might be able to extend the interval between administrations or cease treatments altogether, but this therapy has uneven success rate as it is highly individualized to the companion pet. The success rate for ASIT to alleviate symptoms is approximately 60-80% and SLIT has been around 60%. In my opinion, the success rates should be higher and ultimately demonstrate that either the wrong antigen(s) are being targeted, the testing is flawed, or the dosage is off. Again, as my colleague, Dr. Spiegel, noted, we have to be very careful when prescribing ASIT or SLIT to ensure the testing was correct and that the right antigens are being targeted.
Side effects are noted to be uncommon but they include injection site reactions and the uncommon potential for anaphylactic shock. More than likely, if anaphylaxis is the case, the amount of the dosage may be too high or could be the wrong antigen. As you can see, we should use extreme caution when prescribing this protocol for environmental allergies.
DeBoer, Douglas J., DVM. “Sublingual Immunotherapy: A New Option for Allergy Patients.” Veterinary Medicine. Dvm360.com, 1 Jan. 2014. Web. 16 Oct. 2016. http://veterinarymedicine.dvm360.com/sublingual-immunotherapy-new-option-allergy-patients.
Land, Michael H. “The Future of Food Allergy: Developing New Treatments.” Kids with Food Allergies, Dec. 2014. Web. 16 Oct. 2016. http://www.kidswithfoodallergies.org/page/food-allergy-developing-new-treatments-current-research.aspx.
Spiegel, Ian, VMD. “Oral Immunotherapy: Treating Allergies in Dogs and Cats.” Vetstreet, 14 Jan. 2013. Web. 16 Oct. 2016. http://www.vetstreet.com/our-pet-experts/oral-immunotherapy-good-news-for-treating-allergies-in-pets.
Willemse, T., M. Bardagi, D.n. Carlotti, L. Ferrer, A. Fondati, J. Fontaine, M. Leistra, C. Noli, L. Ordeix, F. Scarampella, S. Schleifer, J. Sinke, and P. Roosje. “Dermatophagoides Farinae-specific Immunotherapy in Atopic Dogs with Hypersensitivity to Multiple Allergens: A Randomised, Double Blind, Placebo-controlled Study.” The Veterinary Journal 180.3 (2009): 337-42. Web. 16 Oct. 2016. http://www.academia.edu/13647021/Dermatophagoides_farinae-specific_immunotherapy_in_atopic_dogs_with_hypersensitivity_to_multiple_allergens_A_randomised_double_blind_placebo-controlled_study.