Digital dermatitis is an extremely contagious, erosive infection of cattle skin caused by Treponeme bacteria. It affects the skin at the heel bulbs, between the claws and around the coronary band. The bacteria penetrate the skin's surface and once within the soft tissue they release enzymes that cause more skin damage, bleeding and pain. Once into the deep tissues of the foot the bacteria can remain there and reactivate later after the initial lesion has healed. In addition to causing lameness in its own right, presence of 'digi' on a farm tends to have an impact on other causes of lameness, causing non-healing sole ulcers or white line lesions, and is often associated with cases of toe necrosis.