Etiological characterization and classification of hoof lesions in sheep from central-western and southwestern Rio Grande do Sul, Brazil (2023-2024)

ABSTRACT: Pododermatitis is prevalent among sheep flocks worldwide, resulting in significant production and economic losses. Dichelobacter nodosus is the main bacterial agent involved in cases of footrot. In Rio Grande do Sul State (southern Brazil), hoof lesions are frequently reported in sheep flocks, yet the agents involved are rarely investigated, which can negatively impact disease control. Thus, this study identified the principal bacteria associated with pododermatitis in sheep in Rio Grande do Sul, characterizing the severity of the lesion observed. A total of 92 animals with pododermatitis from 14 farms in Rio Grande do Sul were evaluated. All lesions were clinically assessed and scored for severity on a scale from 1 to 5, ranging from mild to severe lesions or classified by characteristics of contagious ovine digital dermatitis (CODD). Swabs from the lesions were collected and stored in Stuart medium for bacterial culture under aerobic and anaerobic conditions and in saline solution for DNA extraction and PCR targeting D. nodosus and F. necrophorum. Among the animals analyzed, 3 (3.3%) had lesions classified as score 1, 36 (39.1%) as score 2, 25 as score 3 (27.2%), 19 (20.6%) as score 4, and 4 (4.3%) as score 5. Additionally, five (5.4%) exhibited wounds on the coronary band characteristic of CODD. Only nine samples (9.8%) were positive for D. nodosus, and 27 (29.3%) for F. necrophorum. Positive samples for D. nodosus were also positive for F. necrophorum. Bacterial culture yielded isolates including Enterobacteriaceae, Pseudomonas spp., Staphylococcus spp., Streptococcus spp., Acinetobacter spp., and Gram-positive bacilli. Although D. nodosus and F. necrophorum are commonly reported as the main pathogens in pododermatitis in sheep, their detection frequency in this study was considered low. Nonetheless, the findings demonstrated the circulation of these agents in sheep flocks across Rio Grande do Sul and the variability in pododermatitis severity. The data can be used to plan and implement specific health programs to control pododermatitis in sheep.