| Telazol in one of the most widely used anesthetics because of its short induction period and wide range of safe dosage. However, Telazol doesn’t exhibit good analgesia effect on pigs, which can be optimized by dexmedetomidine hydrochloride due to its advantages in analgesia and immobilization. To date, Telazol combining with dexmedetomidine hydrochloride has been found to be an effective anesthesia system for many animals, but its effect on pigs has been rarely reported. Besides, although demedetomidine hydrochloride has been found to possess high anelasticity on the placental barrier, the permeability of Telazol through the placental barrier has rarely been documented.Herein, a combination of Telazol and dexmetomidine hydrochloride was employed to immobilize Meishan pigs. Body temperatures, heart rates, respiratory rates, degree of blood oxygen saturation, biological reflection, analgesia effect and immobilization effect are monitored during the anesthesia. As a comparison, the same parameters are also recorded in a control experiment employing only Telazol to immobilize pigs. To study the permeability of Telazol through the placental barrier, the high performance liquid chromatograph (HPLC) was employed to detect the concentration of its two constituent drugs, tiletamine and zolazepam, in pigs’peripheral blood and venous blood of umbilical cord.For pigs immobilized with Telezol, the induction period, anesthesia period and recovery period lasted for 3.9±1.0 min,73.1±2.5 min and 91.6±15.4 min, respectively. During the anesthesia, the body temperatures varied from 37.5℃ to 38.8℃; heart rates varied from 65.2 min-1-87.3min-1; respiratory rates were in the range of 20.2 min-1-0.5 min-1; Degrees of blood oxygen saturation were in the range of 92.7%-98.2%. The duration of the analgesia of abdomen is relatively short, leading to an undesirable analgesia effect. Meanwhile, very limited relaxation was observed during the anesthesia.For pigs immobilized with the combination of Telazol and dexmetomidine hydrochloride, the induction period, anesthesia period and recovery period lasted for 2.4± 0.7 min,76.0±8.9 min and 92.7±17.9 min, respectively. All immobilized pigs put up no adverse reaction despite variations of psychological indexes including hypothermia, heart rate dropping, respiratory rate increasing, lowing of partial pressure of blood oxygen, implying high resilience stabilities against above-mentioned changes. During the anesthesia, over 40 min of full analgesia and relaxation could be achieved, much better than the case where only Telazol was used.A facile method to detect tiletamine and zolazepam in in pigs’peripheral blood and venous blood of umbilical cord was developed employing HPLC, which exhibited high recoveries and accuracies. Specifically, stand curves for tiletamine and zolazepam are y=41144.5x+24014.9 (R2=0.9995) and y=32654.4x-9085.7 (R2=0.9992), respectively. The linear plotting range for tiletamine and zolazepam are 10 ng/mL-50μg/mL and 50 ng/mL-50μg/mL, respectively. In the time range of 30-60 min after intramuscular administration of Telazol, no tiletamine was detected in the umbilical cord, while zolazepam was successfully captured with the concentrations ranging from 860.0 ng/mL to 1138.1 ng/mL. The content of zolazepam in the venous blood of umbilical cord was significantly lower than that in the ear margin venous blood at the same time period, with the concentration ratios lying in the range of 0.472-0.782.To summarize, when immobilizing pregnant pigs, the combination of Telazol and dexmedetomidine hydrochloride can achieve a better effect of analgesia and relaxation relative to Telazol only, which makes it an ideal clinical anesthetic. The HPLC-assisted method developed in the present paper enables the detection of tiletamine and zolazepam in the plasma of pregnant pigs. The fact that only zolazepam was detected in the umbilical cord at 30 min-60 min after the intramuscular administration of Telazol indicates that zolazepam is able to cross the placental barrier of pregnant pigs. |
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