Allergen-specific immunotherapy in horses with insect bite hypersensitivity: a double-blind, randomized,...

Area of Science:

• Veterinary Dermatology
• Equine Allergy Research
• Immunotherapy Efficacy Studies

Background:

• Insect bite hypersensitivity (IBH) is a common cause of pruritus in horses.
• Few controlled studies exist on allergen-specific immunotherapy (ASIT) for IBH.
• Overlapping clinical signs with atopic dermatitis necessitate consideration of multiple allergens.

Purpose of the Study:

• To evaluate the efficacy of ASIT in horses diagnosed with IBH.
• To assess ASIT using commercially available allergen extracts and diagnostic tests.
• To determine if multiple allergens improve hyposensitization outcomes.

Main Methods:

• Twenty horses with seasonal pruritus and positive intradermal reactions to Culicoides extract were enrolled.
• Enzyme-linked immunosorbent assay (ELISA) identified concurrent IgE for other allergens.
• Horses received either ASIT (Culicoides plus other allergens) or placebo for one year, with weekly insecticide use.

Main Results:

• No significant differences in clinical scores were observed between the ASIT and placebo groups.
• Both groups showed similar clinical improvement over the one-year study period.
• Improvement in both groups was likely attributable to the use of insect repellent.

Conclusions:

• One year of multiple ASIT using commercial extracts did not demonstrate a beneficial effect in non-stabled horses with IBH.
• Further research is needed to establish effective ASIT protocols for equine IBH.
• Concurrent environmental management, such as insecticide use, may influence study outcomes.