Lameness quietly drains profit from cattle operations, and bovine digital dermatitis (BDD) is one of the main reasons cows go lame. If you run dairy or beef cattle, you have probably already met the lesions. They show up as painful, ulcerative patches on the heels and between the toes, and they get worse fast in wet, muddy, crowded conditions. What happens under the skin is messier than it looks. A spiral-shaped bacterium called Treponema phagedenis now sits near the center of the story. This piece covers what we actually know about T. phagedenis, how it fits into digital dermatitis, why lesions keep coming back, and what works for diagnosis, treatment,…