Comparative study of doramectin and fipronil in the treatment of equine chorioptic mange.
Authors: Rendle D I, Cottle H J, Love S, Hughes K J
Journal: The Veterinary record
Summary
# Editorial Summary Chorioptic mange in horses presents a significant clinical challenge in the UK, where no licensed treatments exist for this common mite infestation, despite available options in other species. Rendle and colleagues conducted a randomised controlled trial comparing two off-licence approaches: subcutaneous doramectin (0.3 mg/kg on days 0 and 14) in eight horses versus topical fipronil spray (0.25% solution applied to limbs below stifle/elbow) in nine horses, with assessments at baseline, 14 and 28 days measuring pruritus behaviour, lesion severity, and mite burden via acetate tape impressions. Both treatments proved equally effective at eliminating clinical signs of pruritus by day 28 and significantly reduced mite numbers; however, neither approach produced significant improvements in dermatological lesion scores over the same period. For practitioners, these findings suggest that whilst either treatment can resolve the immediate parasitic burden and associated itching, healing of secondary skin damage requires additional time or concurrent supportive care, and treatment choice may reasonably be based on factors such as horse temperament, owner compliance, and practical application considerations rather than differential efficacy.
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Practical Takeaways
- •Both doramectin and fipronil are effective at stopping itching and reducing mite burdens in chorioptic mange, with no clear advantage of one over the other
- •Skin lesions may persist after successful parasiticide treatment and resolution of pruritus, suggesting secondary skin damage requires separate management
- •Doramectin requires two injections 14 days apart, whereas fipronil is applied topically — choice may depend on practical considerations and horse temperament
Key Findings
- •By day 28, both doramectin (0.3 mg/kg SC, two doses 14 days apart) and fipronil (0.25% spray) eliminated behavioural signs of pruritus in all treated animals
- •Both treatments produced significant reductions in mite numbers by day 28
- •Neither treatment produced significant reductions in dermatological lesion scores despite mite elimination
- •No significant difference in effectiveness between doramectin and fipronil treatments