Comparison of Intraoperative Behavioral and Hormonal Responses to Noxious Stimuli between Mares Sedated with Caudal Epidural Detomidine Hydrochloride or a Continuous Intravenous Infusion of Detomidine Hydrochloride for Standing Laparoscopic Ovariectomy

Nociceptive pain and anxiety in equines: Physiological and behavioral alterations

Pain and anxiety are two of the most important concerns in clinical veterinary medicine because they arise as consequences of multiple factors that can severely affect animal welfare. The aim of the present review was to provide a description and interpretation of the physiological and behavioral alterations associated with pain and anxiety in equines. To this end, we conducted an extensive review of diverse sources on the topic. The article begins by describing the neurophysiological pathway of pain, followed by a discussion of the importance of the limbic system in responses to pain and anxiety, since prolonged exposure to situations that cause stress and pain generates such physiological changes as tachycardia, tachypnea, hypertension, hyperthermia, and heart rate variability (HRV), often accompanied by altered emotional states, deficient rest, and even aggressiveness. In the long term, animals may show deficiencies in their ability to deal with changes in the environment due to alterations in the functioning of their immune, nervous, and endocrinologic systems. In conclusion, pain and anxiety directly impact the homeostasis of organisms, so it is necessary to conduct objective evaluations of both sensations using behavioral scales, like the horse grimace scale, complemented by assessments of blood biomarkers to analyze their correlation with physiological parameters: Heart rate, respiratory rate, HRV, theparasympathetic tone activity index, lactate and glucose levels, and temperature. Additional tools - infrared thermography, for example - can also be used in these efforts to improve the quality of life and welfare of horses.

Analgesic and Sedative Effects of Epidural Lidocaine-Xylazine in Elective Bilateral Laparoscopic Ovariectomy in Standing Mule Mares

Simple Summary

Elective bilateral ovariectomy in mule mares is recommended to correct undesirable behaviour effects related to oestrus and also in order to improve work performance. This procedure is usually carried out in a standing position with a combination of sedative and analgesic drugs along with local anaesthesia of the ovarian pedicles. The aim of the study was to evaluate the effects of epidural lidocaine-xylazine in sedated standing mules undergoing elective bilateral laparoscopic ovariectomy. The findings suggest that no significant changes were found in heart rate, respiratory rate, rectal temperature with respect to baseline values. Sedation and analgesia were satisfactory in six out of the eight mules. Epidural analgesia with lidocaine-xylazine may be a good alternative to local anaesthetics infiltration of the ovarian pedicle for elective bilateral laparoscopic ovariectomy in standing mule mares, but further studies should be performed.

Abstract

The purpose of this study was to determine the analgesic efficacy and safety of epidural lidocaine-xylazine administration in standing mules undergoing elective bilateral laparoscopic ovariectomy in order to suppress unwanted behaviour. Eight mule mares were sedated with intramuscular 0.05 mg/kg acepromazine followed by 1.3 mg/kg of xylazine and 0.02 mg/kg of butorphanol intravenously. Sedation was maintained by a constant rate infusion of 0.6 mg/kg/h of xylazine. The paralumbar fossae were infiltrated with 30 mL of 2% lidocaine. Epidural anaesthesia was performed at the first intercoccygeal space with 0.2 mg/kg of lidocaine and 0.17 mg/kg of xylazine. After 15 min, bilateral laparoscopic ovariectomy was performed. Heart rate, respiratory rate, rectal temperature, invasive arterial blood pressure, degree of analgesia, sedation and ataxia were evaluated during surgery. The laparoscopic ovariectomy was successfully completed in all animals. Sedation and analgesia were considered satisfactory in six out of the eight mules. In conclusion, caudal epidural block allowed surgery to be easily completed in six out of eight. The animals did not show any signs of discomfort associated with nociception and were mostly calm during the procedures, however additional studies are needed to establish epidural doses of xylazine and lidocaine that result in reliable abdominal pain control in mules for standing ovariectomy.

Comparison of sedation quality and safety of detomidine and romifidine as a continuous rate infusion for standing elective laparoscopic ovariectomy in mares

OBJECTIVE

To compare efficacy and safety of a continuous rate infusion of detomidine hydrochloride and romifidine hydrochloride for standing elective bilateral laparoscopic ovariectomy in mares.

STUDY DESIGN

Blinded, randomized prospective clinical study.

ANIMALS

Eighteen healthy mares presenting for elective bilateral ovariectomy METHODS: Mares were randomly assigned to one of two sedation protocols. Prior to surgery, baseline head height, heart rate, respiratory rate, and postural sway were recorded. An IV loading dose of α2-agonist (46 μg/kg romifidine or 13.9 μg/kg detomidine) was administered. Standing sedation was maintained with a continuous rate infusion of the respective α2-agonist (126 μg/kg/h romifidine or 37.8 μg/kg/h detomidine). Intraoperative measurements included respiratory rate, heart rate, head height, postural sway, and response to surgical stimulus. Postoperatively, fecal output was recorded, and pain scoring was performed using composite pain score and visual analog scales.

RESULTS

Three of 18 horses required additional α-2 agonists: one detomidine and two romifidine and butorphanol. Head height during surgery was lower (p < .001) in mares receiving detomidine. Postural sway around the vertical axis was greater in mares sedated with detomidine rather than romifidine (p = .013). No differences were detected in intraoperative heart rate, postoperative pain scores or postoperative fecal output between sedation techniques.

CONCLUSION

Comparable scores for surgical stimulation and sedation were measured in both sedation groups. No differences in postoperative analgesia or manure production were identified.

CLINICAL SIGNIFICANCE

Romifidine appears suitable as an alternative to detomidine and may limit ataxia and head drop in sedated horses.

Comparison of intraoperative cardiorespiratory and behavioral responses to medetomidine combined with tramadol or butorphanol during standing laparoscopic ovariectomy in horses

The purpose of this study was to assess the cardiorespiratory and behavioral responses to the combination of medetomidine and tramadol (M-T) or butorphanol (M-B) in standing laparoscopic ovariectomy in horses. One ovary was removed under M-T and the contralateral ovary was removed under M-B with at least 4 weeks between operations at random. Horses were sedated using intravenous medetomidine (5 µg/kg) followed by tramadol (1 mg/kg) or butorphanol (10 µg/kg) after 5 min. Sedation was maintained through the repeated injection of medetomidine (1 µg/kg) and tramadol (0.4 mg/kg) or medetomidine (1 µg/kg) and butorphanol (4 µg/kg) every 15 min. Cardiorespiratory function and behavioral responses, including, sedation, ataxia, and analgesia, were assessed during the surgery. There were no significant differences in cardiorespiratory values and sedation and analgesia scores between M-T and M-B. Ataxia scores were significantly lower in M-T than in M-B. This result suggests that M-T could maintain smooth and stable standing surgery with minimal cardiorespiratory changes in horses.

Surgical castration versus chemical castration in donkeys: response of stress, lipid profile and redox potential biomarkers

Background

Castration is a husbandry practice raising important questions on the welfare and physiological status of farm animals. Searching for effective castration methods that minimally compromise the body physiology is worthy of attention. Therefore, this study aimed to evaluate the differential response of biological systems in donkeys to surgical castration versus the chemical one by CaCl₂ with special emphasis on stress, lipid profile, and oxidative stress biomarkers. Donkeys were divided randomly and equally into two groups; the chemical (Ch) and surgical (S) groups (n = 6). The Ch group was chemically castrated by intratesticular injection of 20% CaCl₂ dissolved in absolute ethanol. Blood samples were collected prior to castration and at 15, 30, 45, and 60 days after the beginning of experiment.

Results

Surprisingly, the Ch group at the end of the experiment was characterized by significantly higher cortisol level compared to the S group. TC and LDL-C levels in the S group significantly decreased at day 45, while TG levels significantly increased at days 45 and 60 in comparison with day 0. HDL-C levels at days 30 and 60 in the Ch group significantly increased in comparison with day 0. At day 30 post-castration, HDL-C was significantly higher and LDL-C was significantly lower in the Ch group than the S group. A significant elevation in TC and LDL-C was observed at day 45 and in HDL-C at the end of experimental duration in the Ch group when compared with the S group. TPX level was significantly lower and TAC was significantly higher in the Ch group at day 45 than the S group.

Conclusion

Surgical castration evoked less stress and minor changes in lipid profile and oxidant/antioxidant balance relative to chemical castration by intratesticular 20% CaCl₂ dissolved in absolute ethanol.

Effectiveness of a paraverterbral nerve block versus local portal blocks for laparoscopic closure of the nephrosplenic space: A pilot study

OBJECTIVE

To compare the effectiveness of a paravertebral nerve block vs local portal blocks for laparoscopic closure of the nephrosplenic space in standing sedated research horses.

STUDY DESIGN

Randomized clinical trial.

ANIMALS

Twelve horses were randomly allocated to two groups (n = 6 per group), paravertebral block of nerves T₁₈ , L₁ , and L₂ or local blocks of the three laparoscopic portals.

METHODS

Horses were sedated with dexmedetomidine (4 μg/kg IV and constant rate infusion [CRI] of 2.5 μg/kg/h) and morphine (50 μg/kg IV and CRI of 30 μg/kg/h). According to group allocation, 20 mL of either lidocaine or saline was injected into each paravertebral nerve site or into each local portal site to facilitate laparoscopy for closure of the nephrosplenic space. The overall quality of sedation, analgesia, behavior exhibited during surgery, and ease to perform the surgery were blindly scored by using a visual analog scale (VAS).

RESULTS

Time to complete local anesthesia was similar for both blocks, and there was no difference in VAS scores between groups. Total duration of surgery was also similar between the paravertebral (79 ± 16 min) and local portal blocks (85 ± 25 min) groups.

CONCLUSION

The paravertebral nerve block and the local portal blocks provided similar conditions during surgery and can be used interchangeably for closure of the nephrosplenic space.

CLINICAL SIGNIFICANCE

The paravertebral nerve block can be readily performed and may be useful in surgical procedures.

Prospective randomized investigation of topical anesthesia during unilateral laparoscopic ovariectomy in horses

OBJECTIVE

To compare pain-related responses in mares receiving topical or injected anesthesia of the ovarian pedicle prior to standing unilateral laparoscopic ovariectomy.

STUDY DESIGN

Prospective randomized, blinded, placebo-controlled study.

ANIMALS

Fifteen healthy research mares.

METHODS

Mares were restrained in stocks and administered sedation. A right or left paralumbar ovariectomy was performed by using a laparoscopic portal and two instrument portals. Mares were divided into two treatment groups, and equal volumes of mepivacaine anesthesia were administered either topically (n = 8) or by injection into the ovarian pedicle (n = 7). Saline controls were simultaneously administered topically (n = 7) or by injection (n = 8), and surgeons were blinded to the treatment group. Ovarian removal was performed with traumatic forceps and a blunt tip vessel sealer and divider. Pain responses were measured by operative visual analog scale (VAS) scoring and perioperative serum cortisol response. Visual analog scale and serum cortisol were compared between groups by using Mann-Whitney testing. Serum cortisol concentrations were evaluated using repeated-measures one-way analysis of variance.

RESULTS

Ovaries were removed in all mares by using the described technique without operative complications. Quantity of sedation required to complete the procedure, operative VAS scores, and perioperative cortisol concentrations did not differ between treatment groups.

CONCLUSION

Application of topical mepivacaine to the ovary provided intraoperative analgesia similar to injection of the ovarian pedicle when performing unilateral standing laparoscopic ovariectomy in mares.

CLINICAL SIGNIFICANCE

Topical anesthesia application to the ovary could provide an alternative to laparoscopic needle use, reducing the risk of inadvertent trauma to the pedicle or other visceral organs during laparoscopic ovariectomy.

Bone Marrow Aspiration Does Not Induce a Measurable Pain Response Compared to Sham Procedure

Bone marrow is commonly collected from horses for regenerative medicine applications. Little information is available regarding pain experienced by the horse during bone marrow aspiration. The objective of this study was to characterize horse reaction and pain response during bone marrow aspiration (BMA) compared to a sham (SHAM) procedure. We hypothesized there would be significantly greater horse reaction or pain response measured by salivary cortisol, heart rate variability, and depth and duration of sedation between BMA and SHAM. Twelve university owned horses underwent a BMA and sham procedure, 4 weeks apart in a randomized cross-over design, while sedated with 0.4 mg/kg xylazine hydrochloride. As measures of sedation depth, head height was recorded and sedation level was scored at specific procedural time points. Salivary cortisol was measured immediately before and 2 h after each procedure. Heart rate variability was assessed before, during, and after each procedure. There were no differences in head height, sedation score, or salivary cortisol between groups. No differences were noted between groups in heart rate variability before or during the procedure, but there was a significant decrease in low frequency/high frequency (LF/HF) ratio after the procedure in the BMA group. Over time, there was a significant reduction in LF/HF ratio during the procedure in both groups. Overall, BMA from the sternum did not result in a measurable pain response during, or in the 2 h following the procedure, in comparison to a sham procedure.

A review of equine laparoscopy

Minimally invasive surgery in the human was first identified in mid 900's. The procedure as is more commonly practiced now was first reported in 1912. There have been many advances and new techniques developed in the past 100 years. Equine laparoscopy, was first reported in the 1970's, and similarly has undergone much transformation in the last 40 years. It is now considered the standard of care in many surgical techniques such as cryptorchidectomy, ovariectomy, nephrosplenic space ablation, standing abdominal exploratory, and many other reproductive surgeries. This manuscript describes the history of minimally invasive surgery, and highlights many of the techniques that are currently performed in equine surgery. Special attention is given to instrumentation, ligating techniques, and the surgical principles of equine minimally invasive surgery.