Cytopathology of Superficial Lymph Nodes and Distended Lymphatic Nodules of Horses with Special Reference to Epizootic Lymphangitis in Hawassa City, Ethiopia - Abstract
The study was conducted in drat-horses apparently recovered from Epizootic lymphangitis to evaluate the cytopathological findings in swollen superficial lymph nodes and lymphatic vessels, to identify the possible causative agents of such swellings and to assess the degree of resolution of the pathogen (Histoplasma farciminosum). Fine needle aspiration biopsy (FNAB) samples were collected from 126 cart horses with visible swollen superficial lymph nodes and/or lymphatic vessels (Group I) and 46 apparently recovered carthorses with linear scars on their sternum, face and limbs (Group II). Smears were prepared, stained with modified Giemsa and thoroughly examined for cellular responses and infectious agents. Cytological diagnosis revealed that 89.7% and 10.3% of the samples from the first group were positive for Histoplasma farciminosum and bacteria of unidentified species, respectively. On the other hand, examination of samples taken from group II drat-horses showed lymphadenitis without apparent causative agent in 15.2%, lymphadenitis along with Histoplasma farciminosum in 19.56% and absolutely normal lymph nodes in 65.2% of the horses. Further evaluation of lymphadenitis cases with out apparent causative agent (from group II) indicated that 42.86%, 42.86% and 14.3% of the cases were eosinophilic, neutrophilic, and lymphadenitis of immune stimulation in nature on the basis of dominant cellular reactions. All of the cases of lymphadenitis associated with Histoplasma farciminosum were pyogranulomatous in nature. In general, cytology was found to be a valuable tool in establishing a diagnosis, identifying the process and forming a prognosis. Horses apparently recovered from lymphangitis can harbor the agent in their superficial lymph nodes and act as a source of infection for naive horses. Humane destruction of severe cases and carrier horses should be practiced widely in the country to control epizootic lymphangitis effectively. Further study is required to isolate and characterize the bacterial causes of lymphangitis.