Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central

Abstract

Pesq. Vet. Bras. 32(12):1272-1280, dezembro 2012 1272 RESUMO.-Brachiaria spp. é a principal forrageira utilizada para ruminantes no Brasil Central, mas a sua toxicidade, devida à presença de saponinas esteroidais, torna-se um importante entrave à sua utilização. Neste trabalho descrevem-se 34 surtos e um foco de intoxicação por Brachiaria spp em ovinos, que ocorreram em diferentes épocas do ano. is the main pasture for ruminants in Central-Brazil, but the crucial problem for their utilization is the toxicity due to the presence of steroidal saponins. This paper reports 35 outbreaks of poisoning by Brachiaria spp in sheep. The poisoning occurred in different seasons of the year. Mean morbidity was 23.2% and mean lethality was 88.3%. The occurrence of clinical signs after the introduction of the sheep into the pastures varied from 15 days to more than 12 months. In 90.1% of the outbreaks, sheep younger than 12 months of age were affected. Clinical signs and gross lesions were characteristic of hepatogenous photosensitization, but more acute cases showed edema of the face and ears, without dermatitis or jaundice. The main histologic lesions of the liver were the presence of macrophages with foamy cytoplasm, found mainly in sinusoids, and sometimes containing negative images of crystals. In eight out of 11 farms visited the outbreaks occurred in Brachiaria decumbens pastures, two in B. brizantha pastures, and one in a pasture of B. decumbens, B. humidicola, and Andropogon sp. Saponin concentrations in the pastures of 11 outbreaks varied from 0.3 to 2.56%. The information generated by this report allows the proposal of measures for control and prevention of Brachiaria spp. poisoning in Central--Brazil.

Spontaneous poisoning by Brachiaria decumbens in goats

“…The macroscopic and microscopic lesions observed in goats in this study is consistent of Brachiaria decumbens poisoning (Lemos et al 1998, Riet-Correa & Méndez 2007, Souza et al 2010, Mustafa et al 2012, Tokarnia et al 2012. The main lesion found in the necropsy is the discoloration of the liver, which can be yellow or orange.…”

“…Clinically, the animals intoxicated in this outbreak showed signs similar to those previously reported for goats (Opasina 1985, Lemos et al 1998) and also to sheep (Mustafa et al 2012) and bovine (Souza et al 2010). The clinical course and the age of the animals were quite variable.…”

“…The diagnosis of poisoning by Brachiaria decumbens was based on epidemiological and clinical-pathologic findings, which were very similar to those described in spontaneous and experimental cases of this poisoning in ruminants in Brazil and other parts of the world (Abas-Mazni et al 1985, Opasina 1985, Lemos et al 1998, Brum et al 2007, Mustafa et al 2012, Oliveira et al 2012.…”

“…Different degrees of icterus are often described in poisoning in ruminants . In sheep, icterus is an infrequent finding probably due to acute clinical course of the disease, different from that observed in cattle (Mustafa et al 2012). Icterus was frequently observed in other outbreaks in goats (Abas-Mazniet al 1985, Opasina 1985, Lemos et al 1998.…”

“…Usually the liver usually is increased in size with a yellowish or orange discoloration an accentuated lobular pattern, the gall bladder is distended and urine darkened by bilirubin (Brumet al 2007. Histologically there are swelling, vacuolization and individual necrosis of hepatocytes, periportal fibrosis, bile duct proliferation, pericholangitis, cholangitis, and the presence of crystals or negative images of such crystals in the lumen of the bile ducts and occasionally in the cytoplasm of hepatocytes , Mustafa et al 2012). Characteristic foamy macrophagesare described in liver, mainly in the central zones of the lobule, in hepatic and mesenteric lymph nodes of animals poisoned by Brachiaria spp.…”