Pathological findings associated with experimental infection by Trypanosoma evansi in cats

Five cats were experimentally inoculated with Trypanosoma evansi in order to evaluate the pathological changes induced by this protozoan infection. Clinical signs observed included vomiting, diarrhoea, hyperthermia, weight loss, facial oedema, corneal opacity, lymphadenopathy and hindlimb instability. Reduction in hematocrit was observed from 7 days post-infection (dpi) (P<0.05). One cat died at 40 dpi and the other four cats were humanely destroyed. Necropsy examination was performed in two cats at 56 dpi and two cats at 120 dpi. Gross findings in all cats included generalized muscle atrophy, pale mucosae, icterus of the subcutaneous and serosal tissue and the intima of arteries, lymphadenopathy and splenomegaly. Other findings included corneal opacity, subcutaneous oedema (mainly of the head) and hydropericardium. Trypomastigotes of T. evansi were observed in impression smears prepared from the aqueous humor. Microscopically, there was lymphoid hyperplasia of the spleen and lymph nodes. The animals with corneal opacity had mild corneal oedema and accumulation of fibrin and inflammatory cells (neutrophils and plasma cells) in the anterior chamber. Similar inflammatory cells infiltrated the iris, ciliary body, corneoscleral limbus and conjunctiva.