Aborto induzido por Tetrapterys acutifolia (Malpighiaceae) em bovinos

Abstract

Tetrapterys spp. stand out among the most important toxic plants of the Brazilian Southeast Region. These plants are responsible for a significant number of deaths in over 1-year-old cattle, especially in the states of Rio de Janeiro and São Paulo. This study aims to demonstrate that Tetrapterys acutifolia is also able to induce abortion in cattle and to characterize the clinicpathological alterations in cows and fetuses. Four cows, kept on Brachiaria decumbens pasture before the study, were used in the experiments which were performed on a farm in the county of Barra do Piraí, RJ. The sprouts and young leaves of Tetrapterys acutifolia were collected from the vicinity shortly before being disposed in a trough. The experimental animals ingested the plant material at doses of 2.5g/kg/day (one cow), 5g/kg/day (two cows) and 10g/kg/day (one cow) until abortion occurred. All four cows aborted. The cows showed cardiac arrhythmia, muscular tremors, anorexia, ascites, distended jugular vein, edema of the sternal region and the dewlap, and abortion (23 to 76 days after the beginning of ingestion of the leaves) from the 5th to the 28th day of the experiment. Only one cow died, with characteristic signs of heart failure, 36 days after she had aborted. Gross examination of the fetuses revealed hydrothorax, hydropericardium, hydroperitoneum, nutmeg liver, few petechiae and ecchymoses in the epicardium, and pale areas in transversal sections of the myocardium. The main necroscopic findings in the cow that died were hydrothorax, hydropericardium and hydroperitoneum, engorged vessels at the base of the heart, exceedingly pale heart with marked spots and stripes in transversal sections of the muscle. Distended jugular vein and severe edema in the subcutaneous sternal region and of the abdominal wall were also observed. Histological examination of the fetal hearts revealed interstitial edema with incipient fibrosis and degenerative/necrotic changes of the myocytes. In the succumbed cow, interstitial fibrosis, as well as necrotic areas and/or necrosis of individual myocytes in extensive portions of the heart was found, besides passive congestion in the liver. This study shows that Tetrapterys acutifolia can induce abortion in cattle and, depending on the dosage, cause death.