α2-adrenergic agonists are widely used in sedation, analgesia, and restraint of small ruminants. These drugs bind to α2-agonist receptors in the brain and spinal cord [5]. α2-agonist’ doses used in the present study were determined based on the doses of these drugs used in other studies in small ruminants [13–15]. Nowadays, the laparoscopy technique is widely used in many veterinary procedures (e.g., embryo transfer) [6, 8]. Reducing stress levels in animals during veterinary interventions such as laparoscopy was emphasized [9, 16].
The goats in each group were showed some side effects (such as vocalization, regurgitation, salivation, aspiration, and bloat) during this study. Recumbency in a sedated ruminant is potentially dangerous since they can regurgitate and possibly aspirate this fluid [17, 18]. De Carvalho et al. (2016) demonstrated that IV administration of xylazine in sheep leads to drooling and urination [4]. Sheep exhibited clinical signs of mydriasis, urination, drooling, and vocalization after IV administration of dexmedetomidine IV [3]. Alph2-adrenergic agonists greatly affect oxygenation also [3]. With the positioning used in this study and using the insufflations of abdomen for laparoscopy, these animals are very likely to suffer hypoxemia. Therefore, the animals in this study were given oxygen to try to avoid any hypoxemia.
HR and RR significantly increased from baseline at 15-45 minutes, and cortisol significantly increased from baseline at 45 minutes in the control group. The incidence of laparoscopy-related stress and physiological changes during artificial insemination [8] and embryo transfer [1, 12, 16] was reported in ruminants. Stress and physiological changes can reduce pregnancy rate and productivity in husbandry units [6, 9, 16].
Different α2-adrenergic agonists a significant reduction in RR between 30 and 60 minutes after drug administration. Furthermore, these drugs a significant reduction in HR 5 to 90 minutes and ruminal motility 5 to 120 minutes after drug administration. In my country, xylazine is readily available and very inexpensive, while detomidine and dexmedetomidine are much more expensive. Medetomidine is not readily available anymore. The decrease in physiological variables (HR, RR, and ruminal motility) following α2-adrenergic agonists were reported in other small ruminants such as sheep and goats [17, 18] and camels [2]. By affecting the hormonal and nervous systems, α2-adrenergic agonists reduce HR, RR, and gastrointestinal motility [5, 10, 19]. The serum cortisol levels were significantly lower in different α2-adrenergic agonists groups than in normal saline. Reduction in the concentration of serum cortisol level following α2-adrenergic agonists has been reported in previous studies with another stress such as surgery or restraint or even isolation from other animals [9, 10].
The pregnancy rate of embryos (SCNT) transferred was significantly higher in different α2-adrenergic agonists groups than in normal saline. The use of sedatives during laparoscopic examination in sheep [9] and laparoscopic embryo transfer in sheep and goats [12] was recommended. The pregnancy rate of SCNT embryos in Baguisi et al. (1999)’ study was lower than this study. It may be due to the sedative drugs in this study [20]. It should be noted that the SCNT embryos are valuable and expensive, so it is important to achieve a good pregnancy rate with fewer of them. Two embryos were transferred into uterine horns of recipient goats that were lesser than other uterine horns [21] or tubal [22] embryo transfer. Fonseca et al. (2016) suggested that the improved technique, better animal welfare, and shorter surgery time could be helpful for embryo transfer [12]. There are articles using other procedures (electroejaculator, rumenotomy, etc.) that suggest the use of anesthetics/sedatives improves the outcome they are looking for [19]. Good restraint is important to getting a producer done efficiently and correctly. Actual immobility and lack of response to surgery by the patient likely helps the surgeon perform the embryo transfer properly and more quickly. Most all surgeons can do a better job when the animal is not moving, struggling, and/or vocalizing [14].
The examined animals were laid upside down from 5 to 45 minutes after drug administration; therefore, the assessed duration and quality of sedation might be erroneous. More frequent measurement of cortisol to see if it is increased during surgery or was low throught, would have been very useful.