Allergen immunotherapy for equine insect bite hypersensitivity: Does it reduce clinical signs?

Summary Insect bite hypersensitivity (IBH) is a common, recurrent allergic skin disease of horses. This critically appraised topic evaluated whether therapeutic allergen immunotherapy (AIT) reduces clinical signs in affected horses. Four databases were searched and five therapeutic clinical studies were retained. Controlled studies using crude or commercial Culicoides extracts did not show a consistent benefit over placebo or control treatment. One uncontrolled trial reported improvement but had a high risk of bias. A recent placebo‐controlled study using recombinant Culicoides allergens reported greater improvement in lesion scores and a higher proportion of responders. Conventional extract‐based AIT cannot currently be recommended as reliably effective; recombinant‐allergen AIT is promising but requires confirmation in larger, diverse populations.