Footrot in cattle is caused by which pathogens?

• A. Streptococcus agalactiae
• B. Escherichia coli
• C. Fusobacterium necrophorum, Bacteroides nodosus
• D. Pasteurella multocida

Answer: (C)

Footrot in cattle arises when interdigital skin is infected by anaerobic bacteria that break down the tissue and keratin. The classic culprits are Fusobacterium necrophorum and Bacteroides nodosus (Dichelobacter nodosus). Bacteroides nodosus is the primary agent, producing enzymes that degrade keratin and promote lesion formation. Fusobacterium necrophorum often accompanies the infection, increasing inflammation and tissue destruction, which intensifies lameness. Other organisms listed—Streptococcus agalactiae, Escherichia coli, and Pasteurella multocida—are not typical causes of footrot; they are associated with other diseases or systems in cattle. Thus, the combination of Fusobacterium necrophorum and Bacteroides nodosus best explains footrot.