RESUMEN

The aim of this work was to determine whether a cervical dilation protocol (CDP) composed of only oxytocin can be used to perform transcervical (non-surgical) embryo transfer in sheep (NSET) without affecting the viability of the corpus luteum (CL). Likewise, we evaluated whether a cervical transposing test with a Hegar dilator (CT Hegar test), performed at oestrous time, could be used to screen ewes for NSET (greater or lower chances to transpose the cervix). For that, oestrous and ovulation synchronization was performed in 25 Santa Inês ewes to induce the dioestrous condition. Animals went through the following CDP in a crossover design: E + OX, oestradiol benzoate (100 µg intravenously [IV]) and oxytocin (100 IU IV); OX, oxytocin (100 IU IV); and SAL, saline solution (IV). Using a Hegar dilator, cervical transposing attempts were performed at oestrous (D0) and dioestrous time (D8). The viability of the CL (morphology, luteal blood flow and progesterone values) was evaluated by ultrasonography (colour Doppler and B-mode) and by serum progesterone measurement from D7 to D13. The cervical transposing rate was lower for the SAL group (64%; 16/25; p < .05) and did not differ between the E + OX (88%; 22/25, p > .05) and OX (84%; 21/25, p > .05) groups. No treatment affected the CL viability. The CT Hegar test showed a high sensitivity (85.7%-93.3%), satisfactory accuracy (72%-84%), low false-negative rate (6.7%-14.6%), but high false-positive rate (46%-66.7%). In conclusion, a CDP protocol composed exclusively of oxytocin can lead to good cervical transposing rates and does not affect the viability of the CL. In addition, a screening test (CT Hegar) performed at oestrus can identify ewes for which cervical transposing will likely not occur at NSET.

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The aim of this study was to evaluate the stiffness of foetal lungs, liver, kidneys and placentomes by acoustic radiation force impulse (ARFI) elastography in ovine and to correlate obtained findings with foetal development. Twenty-four ewes were included, and tissue stiffness of foetal lung, liver, kidney and placentome was measured beginning with 10th gestational week by qualitative-quantitative ARFI elastography. A total of 33 healthy lambs were born. Qualitative elastographic analysis permitted to classify maternal and foetal tissues elasticity in decreasing order as follows: placentome, kidney, liver and lung. Regarding quantitative ARFI elastography data, shear wave velocity (SWV) of foetal lung and liver varied. The lung SWV decreased gradually from the 16th to the 21st gestational week (R2  = 0.80; p < 0.001), while liver SWV increased gradually from the 14th to 21st gestational week (R2  = 0.80; p < 0.001). In contrast, the kidneys and placentomes SWV's remained constant through gestation (p = 0.076; and 0.34). ARFI elastography was shown feasible for evaluation of maternal and foetal tissues stiffness in the ovine model. It can be used to demonstrate pulmonary and hepatic stiffness modifications during foetal development.

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A ultrassonografia é uma importante ferramenta para a avaliação de órgãos internos, não invasiva e segura. Com o avanço da tecnologia, abriu-se um leque maior de possibilidades para sua aplicação por meio de novas técnicas que complementam a avaliação de forma mais acurada. Devido às semelhanças fisiológicas e por questões éticas, ovelhas são usadas como modelo experimental, especialmente no que diz respeito ao estudo de tecnologias modernas e que precisam de maior entendimento quanto ao seu funcionamento e aplicabilidade. O modo B ainda é o mais utilizado na rotina clínica e especialmente importante na Obstetrícia Veterinária, pois permite o acompanhamento da gestação e do desenvolvimento embrionário e fetal com avaliações repetidas durante todo o período gestacional. Esta revisão se propõe a mostrar a evolução da ultrassonografia com enfoque no estudo da gestação de ovelhas, seja como modelo experimental ou para aplicabilidade na Medicina Veterinária.

Ultrasonography is an important tool to evaluate internal organs, since it can be done in a non-invasive and safe way. Also, technological advancement opens a greater range of possibilities for its application withnew techniques that allows a more accurate assessment. Due to physiological similarities and ethical issues, sheep are used as experimental model especially in regard to the study of modern technologies. B mode is stillthe most used ultrasound mode in clinical routine and is especially important in Veterinary Obstetrics, since it allows the monitoring of the pregnancy and development of the embryo/fetus with repeated examinations throughout the gestational period. This review brings a vast number of papers on the use of ultrasonography forevaluation and study of the gestation in sheep.

Asunto(s)

RESUMEN

A ultrassonografia é uma importante ferramenta para a avaliação de órgãos internos, não invasiva e segura. Com o avanço da tecnologia, abriu-se um leque maior de possibilidades para sua aplicação por meio de novas técnicas que complementam a avaliação de forma mais acurada. Devido às semelhanças fisiológicas e por questões éticas, ovelhas são usadas como modelo experimental, especialmente no que diz respeito ao estudo de tecnologias modernas e que precisam de maior entendimento quanto ao seu funcionamento e aplicabilidade. O modo B ainda é o mais utilizado na rotina clínica e especialmente importante na Obstetrícia Veterinária, pois permite o acompanhamento da gestação e do desenvolvimento embrionário e fetal com avaliações repetidas durante todo o período gestacional. Esta revisão se propõe a mostrar a evolução da ultrassonografia com enfoque no estudo da gestação de ovelhas, seja como modelo experimental ou para aplicabilidade na Medicina Veterinária.(AU)

Ultrasonography is an important tool to evaluate internal organs, since it can be done in a non-invasive and safe way. Also, technological advancement opens a greater range of possibilities for its application withnew techniques that allows a more accurate assessment. Due to physiological similarities and ethical issues, sheep are used as experimental model especially in regard to the study of modern technologies. B mode is stillthe most used ultrasound mode in clinical routine and is especially important in Veterinary Obstetrics, since it allows the monitoring of the pregnancy and development of the embryo/fetus with repeated examinations throughout the gestational period. This review brings a vast number of papers on the use of ultrasonography forevaluation and study of the gestation in sheep.(AU)

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