Which bacteria are primarily responsible for causing footrot in cattle?

The bacteria primarily responsible for causing footrot in cattle are indeed Fusobacterium necrophorum and Bacteroides nodosus. Fusobacterium necrophorum is an anaerobic bacterium that plays a critical role in the pathogenesis of footrot by invading the damaged tissue between the claws. It produces toxins that lead to tissue necrosis and inflammation. Bacteroides nodosus is also anaerobic and is specific to the footrot condition, working in conjunction with Fusobacterium necrophorum to exacerbate the disease process.

Footrot occurs primarily in wet and muddy conditions, which create an environment conducive to the growth of these bacteria. The combination of mechanical injury and the presence of these pathogens leads to severe inflammation and lameness in affected cattle.

The other bacteria mentioned in the incorrect options do not have the same role or association with footrot in cattle. Understanding the specific bacteria involved in this disease is crucial for effective diagnosis and management.