Experimental Transmission of Bovine Digital Dermatitis to Sheep: Development of an Infection Model.
Authors: Wilson-Welder Jennifer H, Nally Jarlath E, Alt David P, Palmer Mitchell V, Coatney John, Plummer Paul
Journal: Veterinary pathology
Summary
Digital dermatitis, a polymicrobial infection predominantly affecting cattle but also documented in sheep, goats and wild elk, remains poorly understood in terms of its exact aetiology, with bacterial, host and environmental factors all implicated in disease development. Wilson-Welder and colleagues sought to establish a reproducible sheep model of bovine digital dermatitis to facilitate investigation of host-bacterial interactions and pathogenic mechanisms; they abraded the interdigital skin of disease-free crossbred sheep, maintained the area in a moist, anaerobic environment, and inoculated it with macerated tissue from active bovine lesions after three days. Within two weeks, experimentally inoculated feet exhibited characteristic erosive and erythematous lesions, progressing by four weeks to microscopic features consistent with natural disease, including ulceration, hyperkeratosis, ballooning degeneration of keratinocytes and neutrophilic infiltration, with silver staining confirming spirochete penetration of the epidermis. The infection model proved sustainable through serial passage of lesion material into naïve animals, providing equine and ruminant professionals with a controlled system for studying the polymicrobial aetiology and developing improved diagnostic approaches and therapeutics applicable across affected species. For practitioners managing digital dermatitis in any ruminant population, this work offers hope that mechanistic understanding derived from this model will translate to more effective prevention and treatment strategies beyond current management protocols.
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Practical Takeaways
- •This sheep model enables controlled laboratory study of digital dermatitis pathogenesis that is difficult to achieve in cattle, potentially accelerating development of better treatments
- •Demonstration of polymicrobial spirochete involvement and lesion progression may inform better diagnostic approaches and early intervention strategies for digital dermatitis in cattle and other ruminants
- •The moist, anaerobic environment created by wrapping abraded skin was key to infection establishment—highlights importance of hoof moisture management in disease prevention
Key Findings
- •Bovine digital dermatitis was successfully transmitted to sheep using abraded skin and wrapped moist environment, producing lesions within 2 weeks
- •Microscopic examination at 4 weeks confirmed dermis and epidermis changes consistent with bovine digital dermatitis including erosion, ulceration, and neutrophilic infiltrates
- •Silver staining confirmed spirochete penetration into host epidermis in experimentally infected sheep
- •Lesion material from experimentally infected sheep successfully perpetuated infection when passaged to naïve sheep, establishing reproducible model