Intoxicação aguda por metano arsonato ácido monossódico em bovinos

Abstract

O presente trabalho estudou a intoxicação acidental por arsênico em um lote de 24 vacas Girolando, as quais tiveram acesso a pasto pulverizado com herbicida à base de metano arsonato ácido monossódico (MSMA). Os bovinos apresentaram apatia, anorexia e diarreia profusa. Foram necropsiados na fazenda dois animais de 14 que morreram. Os principais achados macroscópicos foram úlceras abomasais e congestão renal. No exame microscópico, as principais lesões observadas foram abomasite e omasite necro-hemorrágica multifocal acentuada e, nos rins, necrose tubular difusa. As concentrações médias de arsênico em vacas com sinais clínicos foram 1,19±0,40, 10,52±2,16 e 76,06±48,37ppm no sangue, leite e fezes, respectivamente. Os níveis de arsênico encontrados em dois animais necropsiados foram 25,58 e 23,85ppm em fígado, e 28,71 e 35,94ppm em rins, respectivamente. No feto de uma vaca necropsiada, os níveis de arsênico mensurados no fígado e rim foram 9,0 e 8,92ppm, respectivamente. A concentração de arsênico no capim do piquete pulverizado foi 111,58ppm. No Brasil, o uso MSMA na composição de pesticidas e herbicidas é permitido somente para uso agrícola, mas não pecuário. A utilização desse ou de outros produtos à base de arsênico na pecuária pode causar altos índices de mortalidade no rebanho, além de diminuição da produção e contaminação de produtos de origem animal.

Vascular injury in spontaneous subacute toxicosis caused by organic arsenic in cattle

“…However except in a study with equines, vascular necrosis is not mentioned in outbreaks of inorganic or organic arsenic poisoning (Dickinson 1972, Pace et al 1997, Neiger et al 2004, Valentine et al 2007, Dantas et al 2012, Bertin et al 2013). …”

“…The toxicodynamics of As in both its forms seems to be similar and vascular changes are implicated as a factor that contributes to the hemorrhagic, degenerative and necrotic lesions observed by many authors (Döbe-reiner et al 1967, Monies 1999, Dantas et al 2012, Bertin et al 2013). However, injuries related to vascular necrosis are not mentioned in prior reports in cattle.…”

“…Ulcerative and erosive lesions on the gastric mucosa and submucosal edema have been observed in inorganic and organic As poisoning (Dickinson 1972, Faires 2004, Neiger et al 2004, Valentine et al 2007, Dantas et al 2012, Bertin et al 2013. The toxicodynamics of As in both its forms seems to be similar and vascular changes are implicated as a factor that contributes to the hemorrhagic, degenerative and necrotic lesions observed by many authors (Döbe-reiner et al 1967, Monies 1999, Dantas et al 2012, Bertin et al 2013).…”

“…Monosodium methanearsonate (MSMA) is too an organic As V , present in herbicide formulations that are used in several countries (Serodio 2014). However, despite widespread use, the only report on accidental toxicosis of cattle with MSMA was a recent investigation (Dantas et al 2012). An experimental challenge using the compound was too described in a pioneering study (Dickinson 1972).…”

Acute lead arsenate poisoning in beef cattle in Uruguay

“…12,19 Mild hemorrhagic and ulcerative lesions in the forestomachs were reported in cattle poisoned by the organic compound monosodium methanearsonic acid and inorganic arsenic trioxide. 1,6,17 It has been suggested that the lesions in the digestive mucosa in arsenic poisoning are the result of endothelial damage. 1,4 Nevertheless, the extensive necrosis of keratinocytes of the ruminal epithelium and the presence of pustules suggests chemical gastroenteritis caused by direct action of the compound on the mucosa, possibly because the pentavalent inorganic arsenical compound is poorly absorbed.…”