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Immunotherapy for Allergic Disease

Shannon Palermo, VMD, University of Pennsylvania



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Immunotherapy for Allergic Disease

Sponsored by Spectrum Veterinary


Although the best form of treatment for allergies is avoidance of the offending allergens, avoidance is not always possible. Suppression or comfort therapies (eg, steroids, antihistamines, cyclosporine, antipruritics) may provide some relief to patients suffering from allergies; however, these therapies are costly, commonly have side effects, and may have side effects with long-term use that are yet unknown. Hyposensitization, a safe and effective alternative, is considered the gold standard for atopy treatment and is the only available treatment that addresses the root cause of clinical signs.

The first step in successful treatment of allergic disease is a proper diagnosis. Without a proper allergy diagnosis, many pets are given multiple medications in an attempt to relieve clinical signs. Only when proper allergen specific testing is initiated can there be an appropriate diagnosis, which is the first step toward successful treatment. Allergen-specific IgE serology and intradermal tests have become widely used to diagnose allergies and are both sensitive and specific.1

Goals of Hyposensitization Therapy

The ultimate goal of hyposensitization therapy is to restore or increase tolerance to the offending allergen by reducing IgE production. In other words, hyposensitization therapy aims to reprogram the immune system to prevent overreaction to the specific allergens that cause problems for the pet. Desensitization occurs by administering increasing doses of the offending allergen, which over time decreases the immune system IgE response. This therapy also results in a decrease in mast cell and basophil production, which both contribute to the secondary inflammation associated with allergy. There are two forms of hyposensitization therapy currently available: subcutaneous injections and sublingual drops.

Subcutaneous Injections

Hyposensitization injections allow patients to develop immunity to specific allergens following a positive allergy test; this results in diminished or absent immune response. Injections provide successful treatment for approximately 65% of patients2 and are administered over a 9-month period, in increasing doses as well as increasing concentrations. This initial hyposensitization period is followed by monthly maintenance injections to maintain the pet’s increased tolerance to allergens. Injections may take several months to become effective, but they can be continued safely throughout the pet’s life. The first injection of each vial should be given in-house to ensure proper compliance.

Sublingual Drops

Sublingual drops are the perfect solution for pets and owners that prefer a needle-free option. Additionally, they may be an effective option for dogs that have “failed injection immunotherapy due to lack of efficacy, adverse reactions, or compliance difficulties.”3 Unlike injectable therapy, daily administration is required; therefore, compliance may be a concern. Although drops may be easier for some pets and clients, they can be costlier than injections over the pet’s lifespan, and response time may be shorter with this form of therapy.2 Food and liquid must be withheld 10 minutes prior to and after administration of the drops for full efficacy.

  Subcutaneous Injections Sublingual Drops
  • Safe for lifelong administration
  • Decades of proven efficacy4
  • Can be tapered
  • No injections required 
  • Alternative for patients that have experienced adverse reaction to injection 
  • Injections may be difficult for some owners
  • Takes several months for full efficacy
  • Require daily administration
  • May be less cost effective over duration of treatment
  • Food and water withheld for 10 minutes before and after administration

References and Author Information

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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