Cervical relaxation for non-surgical uterus access in Santa Inês ewes

Abstract

The present study was composed by two experiments aiming to develop a cervical dilation technique for non-surgical access to Santa Inês ewe's uterus. In Experiment 1, thirty ewes underwent four epidural treatments. The three experimental treatments used 2.0mg/kg ketamine. The group receiving this drug alone was denominated KG, whereas other group had ketamine associated with 0.1mg/kg morphine (KM) and KX a third group had ketamine associated with 0.05mg/kg xylazine (KX). Control treatment was 1mL/7.5kg saline solution epidurally (CON). Cervical dilation was evaluated in both experiments by attempting to pass a metal rod through the cervix. In Experiment 2, three different hormonal protocols for cervical dilation were tested in thirty ewes. Epidural anesthesia with 2.0mg/kg ketamine was the control treatment (KG) and was combined with hormonal treatments: Misoprostol (MI); Oxytocin + Estradiol (OE); Misoprostol + Oxytocin + Estradiol (MOE). In Experiment 1 transposition rate was not different among groups. In Experiment 2, OE presented the highest rate (90%) while MOE presented 86.2%, MI 68.9% and CON 62.1%. The study developed a pharmacological protocol that increased cervical transposition making the non-surgical access to the uterus feasible in Santa Inês ewes. RESUMOO presente estudo teve como objetivo desenvolver uma técnica para acesso não cirúrgico ao útero de ovelhas Santa Inês e foi realizado em duas etapas. No experimento 1, 30 ovelhas foram submetidas a quatro tratamentos epidurais. Os três tratamentos teste usaram 2,0mg/kg de cetamina. O grupo que recebeu apenas cetamina foi denominado KG, enquanto no segundo grupo a cetamina foi combinada com morfina (0,1mg/kg -KM) e um terceiro grupo recebeu cetamina associada com xilazina 0,05mg/kg -KX). No grupo controle (CON), usou-se solução salina (1mL/7,5kg de peso). A dilatação cervical foi avaliada em ambos os experimentos pela tentativa de transposição cervical com uma haste metálica. No experimento 2, três protocolos hormonais de dilatação cervical foram testados em 30 ovelhas. Anestesia epidural com 2,0mg/kg de cetamina foi o tratamento controle (CON), combinada com tratamentos hormonais nos grupos: misoprostol (MI); ocitocina + estradiol (OE); misoprostol + ocitocina + estradiol (MOE). No experimento 1, a taxa de transposição não variou entre os grupos. No experimento 2, OE teve a maior taxa (90%), enquanto MOE apresentou 86,2%, MI i 68,9% e CON 62,1%. O estudo desenvolveu um protocolo farmacológico que aumentou a taxa de transposição cervical, tornando o acesso uterino não cirúrgico viável em ovelhas Santa Inês.

Use of oxytocin to attain cervical dilation for transcervical embryo transfer in sheep

“…The rates of CT reached in the treated groups were similar to CT rates from other studies (81%–95%) that associated prostaglandin, oestradiol benzoate and oxytocin (Figueira et al., 2020; Fonseca et al., 2019a; Leite et al., 2018). Despite the fact that we observed no difference between the treated groups, it was possible to achieve CT rates close to 85% using only oxytocin.…”

“…One strategy to overcome this difficulty in sheep is multiple ovulation and embryo transfer (MOET), in which exogenous hormones analogs (e.g. prostaglandin, oxytocin and oestradiol benzoate) are used to induce cervical dilation before attempting to transpose the cervical folds (Fonseca et al., 2016; Khalifa, Sayre, & Lewis, 1992; Leite et al., 2018). Such drugs are used because their natural analogs are involved in the physiological cascade of events that leads to natural cervical dilation, such as at oestrus and parturition.…”

Cervical transposition test using Hegar dilator at oestrus as a tool to select ewes for transcervical embryo collection

“…(0.1 mg/kg; Vetnil, Louveira, Brazil) and diazepam IV (0.4 mg/kg; Teuto, Anápolis, Brazil). The test at the moment of embryo collection was also preceded by hormonal cervical dilation: Oestradiol benzoate IV (20 µg/ml; Agener União, São Paulo, Brazil) was diluted within 2.5 ml absolute ethyl alcohol and 2.5 ml saline solution and administered 12 hr prior to the moment of embryo collection; cloprostenol IM (0.12 mg; Agener União, São Paulo, Brazil) was administered at the same time; and oxytocin IV (100 IU; Centrovet, Goiânia, Brazil) was administered 15 min prior to embryo collection (Leite et al, ). An epidural anaesthetic was performed with ketamine (2.0 mg/kg; Syntec, São Paulo, Brazil).…”

“…The prostaglandin E 2 , in special, is responsible to induce smooth muscle relaxation and glycosaminoglycan production, which acts separating the collagen fibres and increasing the spaces between them, culminating with the cervical relaxation (Kershaw‐Young, Khalid, McGowan, Pitsillides, & Scaramuzzi, ). In this sense, Leite et al () have demonstrated advances in hormonal protocols for cervical dilation based on the combination of oestradiol and oxytocin previously to the TC method. Moreover, according to Oliveira et al (), the TC method is less invasive, allows animals to be used successively and has no postsurgical effects such as adherence with consequent fertility impairment.…”

Hormonal protocol used for cervical dilation in ewes does not affect morphological embryo quality but reduces recovery rate and temporarily alters gene expression

“…6 However, this method is not applicable in every condition, as it requires technician's training and experience, and the results vary widely according to the breed, parity, and the use of cervical dilation protocols. [7][8][9][10] The dilation of the cervix with hormonal protocols might facilitate NSER as these protocols usually mimic the hormonal pattern observed during oestrous/delivery. Briefly, during the follicular phase of the estrous cycle, and during the process that triggers delivery, there are increases in estradiol, PGF2α (prostaglandin F2α), and oxytocin secretion.…”