When the condition is caused by bacteria, it is termed ulcerative lymphangitis. Both the skin and cutaneous lymphatics of the leg are affected. Lesions begin as papules or nodules that rupture and result in crusts, ulcers, and draining tracts. Regional lymphatics may be swollen, producing a corded appearance. In some cases, the entire leg may be enlarged.
Diagnosis is based on impression smears and bacterial culture.
Fungal culture, skin biopsies, and contrast radiography may be needed to rule out other possible causes. Keeping stalls free of manure and urine and making use of clean bedding will help prevent spread of the disease if it is infectious in nature. Keeping the horse's premises free of wire or other things that could cause cuts or lacerations is another management measure. However, there is another factor that bears consideration, especially when C. pseudotuberculosis is involved as the causative agent of ulcerative lymphangitis. In the western United States, researchers have found C. pseudotuberculosis infection in horses is seasonal.