Poisoning of sheep by Vernonia plantaginoides (Less.) Hieron in Uruguay.

Vernonia plantaginoides (Less.) Hieron, previously known as Vernonia squarrosa, is a rhizomatous subshrub with purple flowers that is prevalent in the natural grassland of Uruguay, Argentina, and southern Brazil. We report an outbreak of V. plantaginoides (yuyo moro) intoxication in sheep in Treinta y Tres Department, northeastern Uruguay. A total of 54 of 463 (12%) recently weaned lambs died 2-7 days after entering a natural pasture that had been invaded by sprouting V. plantaginoides The first cases were found dead. Affected lambs showed marked jaundice, edema of the face, ears, and eyelids, and severe photodermatitis. At the autopsies of 3 lambs, the carcass was yellow, the liver was enlarged with a marked acinar pattern ("nutmeg liver"), and hemorrhages were observed on serous membranes. Microscopic lesions were characterized by diffuse periacinar hepatocellular necrosis and cholemic nephrosis. Three female lambs were experimentally dosed with the aerial parts of V. plantaginoides collected immediately after the outbreak. The lamb that was dosed once with 40 g/kg body weight died after 36 h with severe hepatic necrosis. The lamb dosed with 20 g/kg daily for 4 days showed clinical signs and microscopic lesions in the liver with multiple apoptotic hepatocytes in the periacinar zone. The third lamb, dosed with 30, 17, and 15 g/kg daily over 3 days, respectively, showed transient clinical signs and a rise in liver enzymes, but recovered, and no lesions were found postmortem. These results demonstrate that V. plantaginoides was responsible for severe field outbreaks of poisoning in sheep in Uruguay.

Occurrence of squamous cell carcinoma in Milchschaf sheep in Uruguay / Ocorrência do carcinoma de células escamosas em ovinos Milchschaf em Uruguai

ABSTRACT: In this study, the epidemiological and pathological features of an outbreak of squamous cell carcinoma (SCC) in adult female sheep and a young ram, Friesian Milchschaf breed or crossbreed is described. Seven adult females belonging to an original flock nucleus of 20 animals were affected, as well as a young ram belonging to the same nucleus was affected in other establishment. Multiple verrucous neoplastic masses of several months of evolution were evident in the head region, with local invasion and regional lymph node metastases. Histological studies revealed a cancerous stage of invasion of the dermis and neoplastic proliferation characteristic of invasive SCC, and a pre-cancerous stage with solar elastosis and chronic solar keratosis lesions induced by sunlight. Decrease in latitude, increased level of solar radiation with long exposure to sunlight, and the phenotypic characteristics of the breed are the main factors responsible for the high prevalence of SCC, showing the susceptibility of the Friesian Milchschaf breed and crossbreed in temperate zones as Uruguay.

RESUMO: Neste estudo descrevem-se as características epidemiológicas e patológicas de um surto de carcinoma de células escamosas (SCC) em ovelhas adultas e ram jovem, raça Friesian Milchschaf ou cruza. Foram afetadas sete fêmeas adultas pertencentes a um núcleo de rebanho original de 20 animais, bem como um ram jovem pertencente ao mesmo núcleo em que foi afetado em outro estabelecimento. Múltiplas neoplásicas verrucosas de vários meses de evolução foram evidentes na região principal, com invasão local e metástases de linfonodos regionais. Estudos histológicos revelaram um estágio cancerígeno de invasão da derme e proliferação neoplásica característica do SCC invasivo e um estágio pré-cancerígeno com elastose solar e lesões de ceratose solar crônica induzidas pela luz solar. A diminuição da latitude, o aumento do nível de radiação solar com longa exposição à luz solar e as características fenotípicas da raça são os principais fatores responsáveis pela alta prevalência de SCC, mostrando a susceptibilidade da raça Friesian Milchschaf e cruzada em zonas temperadas como o Uruguai.