Molecular Diagnosis of Footrot and Contagious Ovine Digital Dermatitis in Small Ruminants in the Iberian Peninsula.
Authors: Benito Alfredo A, Anía Silvia, Ramo María de Los Ángeles, Baselga Cristina, Quílez Joaquín, Tejedor María Teresa, Monteagudo Luis Vicente
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Footrot and contagious ovine digital dermatitis remain significant production diseases affecting Spanish and Portuguese flocks, caused respectively by *Dichelobacter nodosus* and pathogenic *Treponema* phylogroups, yet their epidemiology in Iberian small ruminant populations had not been comprehensively characterised. Using quantitative PCR analysis of 105 pooled samples from 100 sheep and five goat herds across Spain and Portugal (plus 15 healthy control flocks), researchers screened for *D. nodosus*, *Fusobacterium necrophorum*, and three pathogenic *Treponema* species (*T. phagedenis*, *T. medium*, *T. pedis*), identifying serogroups where present. Treponema species were ubiquitous across all 120 sample pools including healthy flocks, whilst *D. nodosus* appeared in only 61% of clinically affected farms and mixed infections predominated (68.6% of samples); notably, nearly all *D. nodosus* isolates except serogroup G were detected, frequently in combined infections (35.1%). These findings indicate that digital dermatitis in this region involves complex polymicrobic aetiology rather than single-pathogen disease, and that *D. nodosus* serogroup diversity has significant implications for vaccination strategies—practitioners should consider multi-serogroup vaccine protocols and recognise that hoof disease diagnosis and treatment must account for mixed bacterial involvement rather than targeting single agents.
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Practical Takeaways
- •Molecular diagnosis using qPCR is essential for accurate identification of mixed infections in ovine digital diseases, as culture-dependent methods may miss concurrent pathogens affecting treatment decisions
- •D. nodosus serogroup identification should inform vaccination strategy selection to improve immunization efficiency and herd protection
- •Detection of multiple bacterial agents in apparently healthy flocks warrants implementation of biosecurity and management protocols to prevent disease progression even in asymptomatic populations
Key Findings
- •Treponema spp. were detected in all 120 pooled samples including 15 healthy flocks, indicating ubiquitous presence regardless of clinical disease status
- •Mixed infections occurred in 68.57% of samples with F. necrophorum and/or D. nodosus present in 91.4% of affected herds, but D. nodosus detected in only 61% of clinically affected farms
- •Three pathogenic Treponema phylogroups (T. phagedenis, T. medium, T. pedis) were rare in isolation but found together with other agents in 18 pools (18.57% of affected herds)
- •Dichelobacter nodosus serogroups were identified in combined infections (35.1%) with all serogroups except G detected, suggesting vaccine protocol optimization is needed