Pathological Observations in Horses Naturally Infected with Trypanosoma equiperdum in Western Arsi Zone, Ethiopia

Dourine, a venereal transmitted trypanosomosis is endemic in Ethiopia and it is the major health problem threatening equines. Until recently only few studies were conducted on pathological tissue changes associated with T. equiperdum infection in horses. A cross-sectional study design and purposive sampling were used from November 2014 to June 2015 to identify and select dourine infected horses. Out of 480 (201 mares and 279 stallions) totally examined horses, only twelve mares were positive. Despite attempts made to isolate the parasite using Woo test, no trypanosomes were detected in all of examined blood samples. From the twelve positive mares, two severely affected mares (M1 and M2) with history of sexual infection and suggestive clinical signs as well as serologically positive by CATT/RoTat 1.2 test were purchased and euthanized for postmortem examination. Gross lesions observed in the two euthanized infected mares include, swollen vulva with visible areas of depigmentation, congestion of the mucosa of vagina, thickened and congested mucosa of uterus, ovarian follicular cysts, slightly enlarged and congested spleen, enlarged and swollen liver with multiple necrotic foci. Microscopically, mononuclear cell infiltration mainly of lymphocytes and plasma cells and periglandular inflammation were observed in the vulva, vagina, cervix and uterus. In addition, interstitial mastitis, haemosidrin deposition in the spleen and liver and lymphocytes depletion in the spleen were observed. The gross and histological findings indicated the presence of various organs involvement with severe degree of lesions. Therefore, experimental infections of natural hosts, and unnatural hosts with trypanosome obtained direct from the natural host is recommended in order to study the pathology of dourine in detail in the future.