ulcerative lymphangitis due to mixed bacterial infection in horse

Ulcerative lymphangitis, a bacterial infection primarily caused by corynebacterium pseudotuberculosis and probably mixed infection with other bacteria (e.g. staphylococci, streptococci, …) is an important infectious disease of horses affecting the cutaneous lymphatic vessels. the condition, most commonly associated with poor hygiene and management, wound contamination and insect transmission, is infrequently seen. ulcerative lymphangitis in horse caused by c. pseudotuberculosis also named as “pigeon fever”. this organism is a gram-positive pleomorphic rod-shaped, intracellular, facultative anaerobe with worldwide distribution. the disease is sporadic, with no apparent age, breed, or sex predilections. lesions are most commonly found on a hind limb, especially the fetlock, and rarely above the hock. lesions consist of hard to fluctuant nodules, which abscess, ulcerate, and develop draining tracts. an arabian horse (mare) with dermal clinical signs consists of linear configuration of ulcerated and crusted nodules was referred to histopathologic dermal examination. inspection and palpation were carried out, and the skin was swelled, thickened and hard on clinical examination. histopathologic evaluation of the submitted skin biopsy specimen revealed nodular suppurative ulcerative dermatitis, marked dilation of numerous lymphatic vessels in deep dermis and extensive subcutaneous edema and fibrosis. tissue samples were cultured and corynebacterium pseudotuberculosis, staphylococcus intermedius, trueperella pyogenes were isolated in bacterial culture of deep dermis tissue. ulcerative lymphangitis due to mixed bacterial infection was diagnosed. horses with ulcerative lymphangitis should be treated early and aggressively. typically, iv antimicrobials (penicillin or ceftiofur) alone or in combination with rifampin po are used until lameness and swelling improve. physical therapy (hydrotherapy, hand-walking, leg wraps) and nonsteroidal anti-inflammatory drugs are also recommended. good hygiene and management practices, and early wound treatment and fly control, should be helpful control measures.