Accelerated Immunotherapy Protocols for Atopic Dogs

In the Literature 

Mueller RS, Zablotski Y, Baumann K, et al. A randomized, double-blinded comparison between subcutaneous rush and intralymphatic allergen immunotherapy induction in atopic dogs. Vet Dermatol. 2023;34(2):91-98. doi:10.1111/vde.13138 

The Research … 

Allergen-specific immunotherapy (AIT) for canine atopic dermatitis aims to address the underlying cause of an allergic reaction by building tolerance to allergens over time.¹ AIT generally requires 9 to 12 months to take effect when administered via traditional, nonaccelerated protocols. Several accelerated induction protocols have been evaluated, with the goal of achieving clinical response more rapidly and potentially increasing pet owner compliance.² 

This prospective, randomized, double-blinded study compared the efficacy of AIT in dogs (n = 50) following 2 accelerated induction protocols using an alum-precipitated allergen extract: rush immunotherapy (RIT) with subcutaneous injections and intralymphatic immunotherapy (ILIT) with injections directly into the popliteal lymph node.  

For the RIT protocol, increasing amounts of allergens were injected subcutaneously at 1-hour increments until the maintenance dose was achieved (5 injections total), followed by maintenance doses injected subcutaneously every ≈4 weeks.  

For the ILIT protocol, 0.1 mL of allergen extract was injected into the popliteal lymph node at day 0 and weeks 4, 8, and 12, followed by maintenance doses of immunotherapy administered subcutaneously every ≈4 weeks. 

Baseline pruritus was assessed by owners using the Pruritus Visual Analog Scale (PVAS). Lesion severity was evaluated by the clinician using the Canine Atopic Dermatitis Lesion Index (CADLI). An adapted scoring system was used to determine medication scores. Dogs were re-evaluated using these scoring systems at 1, 3, 6, and 12 months, and a total score of all indexes was calculated. Scores at day 0 and at 12 months were compared to assess the efficacy of RIT and ILIT. In addition, an owner global assessment of treatment efficacy was compared between the groups. 

No significant difference was found between the RIT and ILIT treatment groups at any time point during the study. Both groups had significant improvement in total scores and pruritus scores. Owner-reported global assessment of efficacy was good or excellent in 40% of dogs undergoing RIT and 41.6% of dogs undergoing ILIT. No adverse effects attributed to immunotherapy were documented. 

 … The Takeaways 

Key pearls to put into practice: 

• AIT is generally slow to take effect, and many traditional protocols require weekly injections, which can be difficult for owners to manage and stressful for patients. Two accelerated induction protocols (ie, RIT, ILIT) were safe, well tolerated, and equally effective to accelerate the onset of immunotherapy. A good to excellent response to therapy was achieved in ≈40% of patients undergoing RIT or ILIT.  

• Whether RIT or ILIT would be preferred for most patients is unclear. RIT involves hospitalization with intense monitoring for 1 day, which can be costly, and increased risk for an allergic reaction, although none were reported in this study; overall safety appears excellent. ILIT does not require hospitalization with monitoring, but the long-term safety of alum-precipitated allergens administered intralymphatically is not yet clearly established.  

• In the United States, aqueous allergens are typically used for veterinary immunotherapy, and alum-precipitated allergens are not available. The efficacy of ILIT using aqueous allergens has not been evaluated.