Trema micrantha is a tree widely distributed in Brazil. This paper describes new epidemiological and pathological aspects of this plant poisoning in equids. Two adult horses, Criollo breed and two donkeys from different locations were naturally poisoned by Trema micrantha after consuming large amounts of the plant which was available to them due to pruning. Also an adult horse from another ranch, which was undergoing dietary restriction, was poisoned after consuming the lower parts of a large number of young T. micrantha trees. Clinically, in all cases, the disease was characterized by neurological symptoms that started 3 to 4 days after consumption of the plant, with a clinical course that varied 2 to 4 days (abbreviated by euthanasia). The main gross findings were in the liver, which had slightly increased lobular pattern evident, and in the central nervous system (CNS) with multiple yellowish areas, foci of malacia and hemorrhage, especially in the brainstem and cerebellum. Histologically, there was acute liver necrosis with marked edema of the CNS with fibrinoid vessel wall degeneration, hemorrhage and thrombosis as well as neutrophil infiltration. Other changes in the brain were Alzheimer type II astrocytes in the gray matter, accumulation of Gitter cells and Wallerian degeneration near to vascular lesion foci.
Poisonous plants; Trema micrantha; Cannabaceae; plant poisoning; equids; hepatic necrosis; malacia
