Lysosomal storage disease induced by Sida planicaulis (Sin. Sida carpinifolia) (Malvaceae) in sheep in the state of Rio de Janeiro

ABSTRACT Ingestion of S. planicaulis (Sin. S. carpinifolia) causes lysosomal storage disease in sheep. The main toxic compound of this plant, swainsonine, inhibits the enzymatic activity of α-mannosidase I and II, resulting in lysosomal storage of glycoproteins. We describe a case of spontaneous poisoning by S. planucaulis in Rio de Janeiro state, Brazil. Physical examination of affected animals revealed proprioceptive deficit, motor incoordination, staggering movement, and head tremors. Histopathological evaluation showed severe swelling/cytoplasmic vacuolization in Purkinje neurons, with a foamy appearance and occasional karyolysis or karyopyknosis, and intense vacuolization of acinar cells of the pancreas and, less markedly, thyroid follicular cells. The positive lectin-histochemistry labeling for Con A, WGA and sWGA lectins characterized the disease as a glycoproteinosis. The ultrastructural evaluation revealed numerous vacuoles up to 2.5μm in diameter bounded by membranes up to 20nm thick in pancreatic acinar cells. The diagnosis of S. planicaulis toxicity was established based on epidemiological data, clinicopathological, lectino-histochemical, and ultrastructural findings. This is the second report of spontaneous poisoning of sheep by S. planicaulis in Brazil, but the first in the Southeastern Brazil.