The efficacy of topical Nitric Acid and Zinc Complex Solution in the treatment of aural plaque in horses
Year: 2025
Type: preprint
Abstract: Background Equine aural plaque caused by equine papilloma viruses is common worldwide, affected horses can show severe clinical signs. In some countries affected horses are not allowed in competitions or shows due to viral etiology. Since lesions persist, showing no spontaneous regress, effective and safe treatment is desired. Today, the only treatment with consistent efficacy is imiquimode (Aldara®). Treatment time is long and adverse effects common, sometimes so severe that treatment cannot be completed. In humans even pediatric, papilloma warts are successfully, safely treated with topical nitric-zinc complex solutions inducing a painless caustic effect. Objectives The objective to retrospectively evaluate effectiveness and adverse effects with topical treatment with a solution containing nitric acid and zinc (Oxalic® or Verrutop®). Comparing this treatment with results from published studies using imiquimod (Aldara®). Study design Retrospective case series. Methods Records from horses with aural plaque diagnosed at Equine Clinic of the University Animal Hospital and Equine Clinic Täby Sweden during 2012-2022 were reviewed. Included horses were treated topically with nitric acid and zinc solution (Oxalic® or Verrutop®), uni- or bilateral every other week until remission, successful outcome defined as no remaining lesions during a 12-28 month follow up. Results Twelve horses were included, eight bilaterally affected. In total were 20 ears treated, in 17 lesions healed with one to five treatments, several needed only one. The three remaining ears, substantially improved, the horses showing no clinical signs. Treatment period varied between two to 20 weeks, none developing adverse effects. Compared with imiquimod (Aldara®), treatments occasions were fewer, no adverse effects were seen, whereas painful ulcerations and erosions were recorded in all imiquimod (Aldara®) treated horses. Main limitations Retrospective study, small sample size, not blinded, and no control group included. Lesions were diagnosed by macroscopic appearance, no PCR for virus detection or histology were made.
Authors: Lii Leo, Kerstin Bergvall
Institution: Swedish University of Agricultural Sciences
Language: English
Subfield: Equine
Field: Veterinary
Domain: Health Sciences
Open Access status: gold
OpenAlex ID: W4414789759
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