Congenital caprine goiter in northwestern Rio Grande do Sul state, Brazil/ Bocio congenito em caprinos no Noroeste do Rio Grande do Sul, Brasil

The epidemiological, clinical, and anatomopathological aspects of an outbreak of congenital caprine goiter are described in this article. The cause of the congenital goiter and neonatal deaths was attributed to the absence of mineral supplementation with iodine to the pregnant dams. Clinically, all neonatal dead goats presented with marked swelling on the cranioventral cervical area and diffuse body alopecia. One of the dead kids was submitted to necropsy, and changes consisted of marked, symmetrical enlargement of both thyroid lobes, which were also firm, compact, and dark red. Histologically, changes were characteristic of diffuse hyperplastic goiter and consisted of: 1) marked follicular thyroid hyperplasia and hypertrophy; 2) formation of heterogeneous thyroid follicles due to the variable amounts of luminal colloid; and 3) presence of endocytic vacuoles, which represent colloid endocytosis and demonstrate activity of the thyroid gland. Key words: diseases of goats, hyperplastic goiter, iodine deficiency, congenital anomalies. Os aspectos epidemiologicos, clinicos e anatomopatologicos de um surto de bocio congenito em caprinos sao descritos. A etiologia dessa condicao foi associada a ausencia de suplementacao mineral com iodo para as cabras prenhes, e constituiu o fator responsavel pela natimortalidade nesse surto. Clinicamente, todos os natimortos apresentaram marcado aumento de volume na regiao cervical ventral cranial e alopecia difusa. Na necropsia de um dos cabritos natimortos, observouse acentuado aumento de volume simetrico de ambos os lobos da glandula tireoide, que eram firmes, compactos e vermelhoescuros. Histologicamente, as lesoes eram caracteristicas de bocio hiperplasico difuso e consistiam de: 1) marcada hiperplasia e hipertrofia do epitelio folicular; 2) formacao de foliculos tireoidianos marcadamente heterogeneos, devido principalmente a quantidade variavel de coloide intraluminal; e 3) presenca de vacuolos endociticos, que representam a endocitose do coloide e demonstram a atividade da glandula tireoide. Palavras-chave: doencas de caprinos, bocio hiperplasico, deficiencia de iodo, anormalidades congenitas.