# The Treatment of Contagious Ecthyma in Lambs with a Local Anaesthetic/Antiseptic Wound Formulation Lowers Serum Amyloid A Responses

## TL;DR

A non-antibiotic topical treatment for contagious ecthyma in lambs reduces inflammation, offering a promising alternative to antibiotics.

## Contribution

Demonstrates a non-antibiotic topical formulation effectively lowers systemic inflammation in lambs with contagious ecthyma.

## Key findings

- Treated lambs showed significantly lower SAA levels at T14 in experimental infections compared to controls.
- In natural outbreaks, SAA levels in treated lambs decreased over time, while controls remained high.
- The treatment reduced systemic inflammation without using antibiotics, potentially mitigating antimicrobial resistance risks.

## Abstract

Contagious ecthyma (CE) is a skin disease of small ruminants with significant economic impact and welfare concerns. Vaccination is the main preventive strategy for CE, although in many countries, licenced vaccines are unavailable. Treatment typically involves antibiotics to control secondary infections, increasing the risk of antimicrobial resistance. The objective of this study was to evaluate the therapeutic effect of a non-antibiotic topical anaesthetic/antiseptic therapeutic formulation (Tri-Solfen®; T-S; Medical Ethics, Australia/MultiSolfen®; M-S; Dechra, UK) on lambs with contagious ecthyma. The concentration of a marker of systemic inflammation, serum amyloid A (SAA), was measured during the clinical phase of CE in naturally and experimentally infected lambs, in cohorts either treated or not treated with the product. In the experimental infection, the treatment modified the SAA response, peaking earlier and at lower levels than in controls and showing significantly lower values at the completion of the experimental period than in controls. In the natural outbreak, SAA levels significantly decreased over time in the treated cohort, whereas in controls, levels remained stable at high values. These results indicate that this topical formulation reduces systemic inflammation in lambs with CE, providing supportive evidence that this is a promising non-antibiotic therapeutic alternative to current practice.

Contagious ecthyma (CE) is a widespread, highly contagious zoonotic skin disease of small ruminants caused by the Orf virus (ORFV), leading to substantial economic losses and welfare concerns. There is no specific treatment, with topical antiseptics and oral or parenteral antibiotics often administered for preventing secondary infections, risking antimicrobial resistance. This study assessed the effect of treating CE in lambs with an antibiotic-free topical anaesthetic/antiseptic formulation (Tri-Solfen®; T-S; Medical Ethics, Australia/MultiSolfen®; M-S; Dechra, UK). Serum amyloid A (SAA), a marker of systemic inflammation, was measured in both experimentally and naturally infected lambs allocated to treated and untreated groups. Samples were collected prior to (T0) and at 2 (T2), 7 (T7) and 14 (T14) days post-treatment in experimentally infected lambs and at T0, 10 (T10) and 20 (T20) days post-treatment in naturally affected lambs. In the experimental infection, SAA concentrations were lower in the treated group than in controls at T7 and significantly lower at T14. In the natural outbreak, SAA concentrations significantly decreased over time in the treated group, with a consistent trend toward lower values than in controls. These findings indicate that this therapeutic formulation reduces systemic inflammatory responses in lambs affected by CE, supporting its use as an alternative to antibiotics.