Evaluation of pulmonary maturity in bovine neonates: analysis of amniotic fluid / Avaliação maturidade pulmonar em neonatos bovinos: análise do líquido amniótico

ABSTRACT

Considering the representativeness of dairy cattle in our country, the concern about the mortality rates of the animals increases each time. Regarding to calf mortality, the Respiratory Distress Syndrome (RDS) has an important relevance during the neonatal period, and it is present in immature lungs. The amniotic fluid is in direct contact with the fetus, and it is able to offer evidence about his maturity. The aim of this study was to standardize the characteristics of the amniotic fluid, color, aspect, viscosity, quantification of lamellar body and surfactant evaluation by the Clements test and cytology, of term-born, mature and healthy calves. There were used 50 Black and White Holstein calves, which mothers were observed at calving in order to collect the amniotic fluid by puncture in the moment of exposure of the fetal membrane through the vaginal canal. Most amniotic fluid had a clear and hazy appearance due to varying degrees of viscosity and the presence or absence of clots. The Clements test could be adapted to the bovine species by the modification consisting in the addition of 3mL of amniotic fluid and 1mL of 95% ethanol. The methodology of the lamellar body count by the automated particle counter is not applicable for the bovine because of the small size of their lamellar body. The Nile Blue staining is unsatisfactory on predicting fetal maturity on the bovine species, different from cytology using Hematoxylin-Shorr stain. The presence of orange cells, increase in large amounts at the end of pregnancy. The cell stained orange counting, cells which are found in great amounts at the end of pregnancy. The present study stablished new parameters for evaluation of fetal and pulmonary maturity in the bovine species.(AU)

RESUMO

O objetivo desse estudo foi reunir novos dados práticos sobre a avaliação da maturidade pulmonar em neonatos bovinos, padronizando as características do líquido amniótico de bezerros maduros e hígidos, o que proporcionará a oportunidade de tratamento precoce dos animais prematuros, evitando prejuízos econômicos, principalmente quando consideramos os animais de alto valor genético. Amostras de líquido amniótico foram coletadas de 50 vacas da Raça Holandesa Preta e Branca. Corpos lamelares foram identificados por microscopia eletrônica de transmissão como estruturas de tamanho aproximado de 130nm, o que impede sua contagem em analisadores automáticos. O teste de Clements sofreu adaptações de técnica e se mostrou viável com a diluição de 3mL de líquido amniótico em 1mL de etanol a 95%. A citologia utilizando o método de Hematoxilina-Shorr, diferentemente do teste de Azul de Nilo, foi eficaz na identificação das células orangiofílicas, indicativas de maturidade fetal. Esses métodos mostraram-se originais e úteis ferramentas para a avaliação de maturidade pulmonar na espécie bovina, porém estudos com bezerros prematuros ainda são necessários.(AU)