Digital dermatitis (DD) is a bacterial foot disease that causes painful foot lesions in adult dairy cattle. It is most frequently a problem for dairy cows that live in overcrowded, unsanitary conditions. It is a major cause of lameness in cattle, due to pain and discomfort resulting from inflammation and skin damage. A similar form of the disease causes contagious ovine digital dermatitis in sheep and dairy goats. DD is also involved in the development of three other forms of bovine foot lesions; toe necrosis, non-healing sole ulcers, and non-healing white line disease.
Certain cows are more susceptible than others to DD. Lesions occur along the coronary band or on the skin adjacent to one or both of the cattle's feet. DD has been described in stages of progression, although its presentation varies geographically. In the United States, most cattle suffer from a proliferative form of DD (where it is often referred to as papillomatous DD or PDD), with a more erosive form occurring in Europe. The four stages consist of M1 (early stage), M2 (ulcerative stage), M3 (scabbing stage), and M4 (chronic stage).
|M1 (early stage)||Small circumscribed granulomatous area; generally non-painful|
|M2 (ulcerative stage)||Larger lesions; painful on palpation|
|M3 (scabbing stage)||Scabs form over ulcerations|
|M4 (chronic stage)||Surface proliferation or dyskeratosis; generally non-painful; remains infectious; ability to reactivate M1 stage|
The primary bacteria responsible for DD is thought to be of the genus Treponema
(treponemes), the same genus responsible for Treponemal disease and human periodontitis in humans. The six groups of treponemes most commonly found include T. denticola, T. maltophilum, T. medium, T. putidum, T. phagedenis
, and T. paraluiscuniculi
. Treponemes are able to infect multiple hosts, including humans. Other bacterial agents identified in DD lesions have included Borrelia burgdorferi, Mycoplasma spp, Bacteroides spp, Campylobacter spp
and Candidatus Amoebophilus asiaticus
DD is suspected to be transmitted from direct skin to skin transmission from contact with infected cattle, or possibly other animals, even humans. Indirect transmission through contamination of hoof trimming equipment used by professional farriers.