Video Endoscopy-Guided Intrabronchial Spray Inoculation of Mycobacterium bovis in Goats and Comparative Assessment of Lung Lesions With Various Imaging Methods

Bovine tuberculosis (bTB) not only poses a zoonotic threat to humans but also has a significant economic impact on livestock production in many areas of the world. Effective vaccines for humans, livestock, and wildlife are highly desirable to control tuberculosis. Suitable large animal models are indispensable for meaningful assessment of vaccine candidates. Here, we describe the refinement of an animal model for bTB in goats. Intrabronchial inoculation procedure via video-guided endoscopy in anesthetized animals, collection of lungs after intratracheal fixation in situ, and imaging of lungs by computed tomography (CT) were established in three goats using barium sulfate as surrogate inoculum. For subsequent infection experiments, four goats were infected with 4.7 × 10² colony-forming units of M. bovis by intrabronchial inoculation using video-guided endoscopy with spray catheters. Defined amounts of inoculum were deposited at five sites per lung. Four age-matched goats were mock-inoculated. None of the goats developed clinical signs until they were euthanized 5 months post infection, but simultaneous skin testing confirmed bTB infection in all goats inoculated with M. bovis. In tissues collected at necropsy, M. bovis was consistently re-isolated from granulomas in lymph nodes, draining the lungs of all the goats infected with M. bovis. Further dissemination was observed in one goat only. Pulmonary lesions were quantified by CT and digital 2D radiography (DR). CT revealed mineralized lesions in all the infected goats ranging from <5 mm to >10 mm in diameter. Small lesions <5 mm predominated. The DR failed to detect small lesions and to determine the exact location of lesions because of overlapping of pulmonary lobes. Relative volume of pulmonary lesions was low in three but high in one goat that also had extensive cavitation. CT lesions could be correlated to gross pathologic findings and histologic granuloma types in representative pulmonary lobes. In conclusion, video-guided intrabronchial inoculation with spray catheters, mimicking the natural way of infection, resulted in pulmonary infection of goats with M. bovis. CT, but not DR, presented as a highly sensitive method to quantify the extent of pulmonary lesions. This goat model of TB may serve as a model for testing TB vaccine efficacy.

Determination of the Minimum Infusion Rate of Alfaxalone Combined with Electroacupuncture in Goats

Simple Summary

Goats have been used as animal models in research and are increasingly kept as pets like dogs and cats. Total intravenous anesthesia (TIVA) is increasingly used in companion animals. Electroacupuncture (EA) has been proven to produce analgesia, therefore, the objective of this study was to investigate the effect of EA on alfaxalone-based TIVA in goats. In this current study, the minimum infusion rate (MIR) of alfaxalone was determined in a combination with EA. The findings found that EA reduces the alfaxalone MIR required to prevent purposeful movement of the extremities in response to standardized noxious. In conclusion, EA provided analgesia, reduced the MIR of alfaxalone-based IV anesthesia, and thereby alleviated the adverse cardiorespiratory effects associated with alfaxalone anesthesia in goats.

Abstract

Total intravenous anesthesia (TIVA) is increasingly used in companion animals. The effect of electroacupuncture (EA) on alfaxalone-based TIVA has not been previously reported in goats. Therefore, the objective of this study was to determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement of the extremities in response to standardized noxious stimulation during its combination with EA in goats. Twelve clinically healthy goats weighing 18.5 ± 2 kg were randomly assigned to two groups (six goats/group). Alfaxalone alone (ALF group) and alfaxalone combined with EA (EA-ALF group). In the EA-ALF, alfaxalone was administered 30 min after EA stimulation. For induction of anesthesia, a bolus of alfaxalone was given at 3 mg/kg IV, and an infusion dose of 9.6 mg/kg/h was initially set for maintenance. The MIR of alfaxalone in both groups was determined by testing for responses to stimulation (clamping on a digit with Vulsellum forceps) at 10-min intervals after induction of anesthesia till the entire period of the experiment. Cardiopulmonary parameters and nociceptive threshold were measured throughout anesthesia. The median alfaxalone MIR was significantly lower in the EA-ALF group than the ALF group [9 (4.8–9.6) and 12 (11.4–18)], respectively; p = 0.0035). In the ALF group, goats anesthetized with MIR showed a significant increase in heart rate and cardiac output (p < 0.0001 and 0.0312, respectively), and decrease in respiratory rate (p < 0.0001), hemoglobin oxygen saturation (p = 0.0081), and rectal temperature (p = 0.0046) compared with those in the EA-ALF. Additionally, goats in the EA-ALF showed a higher nociceptive threshold than those in the ALF group (p < 0.0001). EA provided analgesia, reduced the MIR of alfaxalone-based IV anesthesia and thereby alleviated the adverse cardiorespiratory effects associated with alfaxalone anesthesia in goats.

Characteristic patterns of EEG oscillations in sheep (Ovis aries) induced by ketamine may explain the psychotropic effects seen in humans

Ketamine is a valuable anaesthetic and analgesic that in recent years has gained notoriety as a recreational drug. Recently, ketamine has also been proposed as a novel treatment for depression and post-traumatic stress disorder. Beyond its anaesthetic actions, however, the effects of ketamine on brain activity have rarely been probed. Here we examined the cortical electroencephalography (EEG) response to ketamine of 12 sheep. Following ketamine administration, EEG changes were immediate and widespread, affecting the full extent of the EEG frequency spectrum measured (0–125 Hz). After recovery from sedation during which low frequency activity dominated, the EEG was characterised by short periods (2–3 s) of alternating low (<14 Hz) and high (>35 Hz) frequency oscillation. This alternating EEG rhythm phase is likely to underlie the dissociative actions of ketamine, since it is during this phase that ketamine users report hallucinations. At the highest intravenous dose used (24 mg/kg), in 5/6 sheep we observed a novel effect of ketamine, namely the complete cessation of cortical EEG activity. This persisted for up to several minutes, after which cortical activity resumed. This phenomenon is likely to explain the ‘k-hole’, a state of oblivion likened to a near death experience that is keenly sought by ketamine abusers.

Chirality of Central Nervous System (CNS) Acting Drugs: A Formidable Therapeutic Hurdle Against CNS Diseases

BACKGROUND

Over fifty percent of drugs being used clinically are chiral and 90% of them are racemates. Unfortunately, they have both adverse and beneficial effects on body systems.

METHODS

Because of the erratic effects of chiral compounds on body functional systems, literature search was carried out with a view to identify CNS chiral drugs, their clinical advantages and disadvantages, unique physicochemical properties and structural modifications into safer drugs.

RESULTS

Findings have shown that majority of CNS and non-CNS acting drugs have chiral functional groups that may occur as either dextrorotatory (clockwise) or levorotatory (anticlockwise) or racemates which are inert. Sometimes, the enantiomers (optical isomers) could undergo keto-enol tautomerism, appearing in either acidic or basic or inert form. Chiral CNS acting drugs have agonistic and antagonistic effects, clinical advantages, disadvantages, and special clinical applications, possible modifications for better therapeutic effects and possible synthesis of more potent drugs from racemates. Clockwise chirality may be more effective and safer than the drugs with anticlockwise chirality. When chiral drugs are in racemate state they become inert and may be safer than when they are single. Also, diastereoisomers may be more dangerous than stereoisomers.

CONCLUSION

Therefore, chiral compounds should be adequately studied in lab rodents and primates, and their mechanisms of actions should be comprehensively understood before being used in clinical setting. Since many of them are toxic, their use should be based on principle of individualized medicine. Their molecular weights, functional groups, metabolites, polymers and stereoisomers could be valuable tools for their modifications.

COMPARISON OF PROPOFOL CONSTANT RATE INFUSION AND ISOFLURANE FOR MAINTENANCE OF ANESTHESIA IN SPEKE'S GAZELLE, GAZELLA SPEKEI

The aims of this study were to determine if a propofol constant rate infusion (CRI) in Speke's gazelle, Gazella spekei, would serve as an effective alternative maintenance anesthetic, result in shorter recovery times, and improve anesthetic recovery quality when compared with isoflurane. Eight adult gazelle were enrolled in this complete crossover study with a minimum 3-wk washout period. All gazelle were induced with 10 mg/kg intravenous propofol and maintained with either propofol CRI (0.4 mg/kg/min) or isoflurane (1-3%) for 45 min. Animals were monitored for anesthetic depth and physiologic variables including heart and respiratory rates, oxygen saturation, end-tidal carbon dioxide, indirect blood pressure, and temperature every 5 min. Blood gas samples were analyzed within the first 10 min following anesthetic induction and within the last 10 min of anesthesia. Recovery times were recorded. Recovery quality was classified by a residual ataxia grading scale. Seven gazelle completed the study by undergoing both anesthetic treatments; one female (12 yr old) developed complications 2 days after isoflurane anesthesia, consisting of seizures, azotemia, leukocytosis, hypocalcemia, and hypomagnesemia but was treated successfully. Propofol anesthesia resulted in lower respiratory rates compared with isoflurane and a decrease in respiratory rate over time. Propofol CRI maintained blood pressure values closer to physiologically normal ranges compared with isoflurane for 45 min of anesthesia. Recovery times were comparable between propofol and isoflurane treatments. While individuals receiving propofol had higher residual ataxia scores compared with individuals receiving isoflurane, differences were not clinically important. This study demonstrated that propofol CRI (0.4 mg/kg/min) is an effective maintenance anesthetic agent in healthy adult Speke's gazelle for noninvasive procedures with endotracheal intubation and intermittent positive pressure ventilation.

Total intravenous anaesthesia in a goat undergoing craniectomy

BACKGROUND

Cerebral coenurosis is a disease of the central nervous system in sheep and goats, and is usually fatal unless surgical relief is provided. Information regarding neuroanaesthesia in veterinary medicine in goats is scant.

CASE PRESENTATION

We describe anaesthetic management of an intact female goat (2 years; 16 kg) presented for craniectomy. The goat was sedated with xylazine (0.05 mg kg-1, i.m.) and morphine (0.05 mg kg-1, i.m.). General anaesthesia was induced 20 min later with propofol and maintained with a constant rate infusion of propofol (0.2 mg kg-1 min-1). A cuffed endotracheal tube was placed and connected to a rebreathing (circle) system and mechanical ventilation with 100% oxygen was initiated. A bolus of lidocaine (1 mg kg-1), midazolam (0.25 mg kg-1) and fentanyl 2.5 μg kg-1 was delivered via the intravenous route followed immediately by a constant rate infusion of lidocaine (50 μg kg-1 min-1), midazolam (0.15 mg kg-1 h-1) and fentanyl (6 μg kg-1 h-1) administered via the intravenous route throughout surgery. Craniectomy was undertaken and the goat recovered uneventfully.

CONCLUSION

Total intravenous anaesthesia with propofol, lidocaine, fentanyl and midazolam could be an acceptable option for anaesthesia during intracranial surgery in goats.

Effect of Mesenchymal Stem Cell Application on the Distracted Bone Microstructure: An Experimental Study

PURPOSE

Distraction osteogenesis (DO) is a surgical technique used to regenerate bone. The aim of this study was to improve bone quality and quantity during DO by the addition of mesenchymal stem cells (MSCs).

MATERIALS AND METHODS

The study was conducted on 12 goats assigned to a study group or a control group. In the study group, DO was aided with MSCs. Bone quality was assessed using energy dispersive x-ray (EDX), a scanning electron microscope (SEM), and histology. The histologic assessment was performed by measuring trabecular bone (TB) thickness in sections stained with hematoxylin and eosin (H&E) and by measuring osteoid bone percentage in sections stained with Masson trichrome (MT).

RESULTS

EDX showed an increase in calcification in the study group (mean Ca(2+), 17.58%; standard deviation [SD], 4.9%) compared with the control group (mean Ca(2+), 14.17%; SD, 6.7%). However, the increase was not statistically significant (P = .3354). Histomorphometric analysis of the H&E samples showed an increase in TB size in the study group (mean TB, 174.7 μm; SD, 33.5 μm) compared with the control group (mean TB, 115.4 μm; SD, 19.6 μm), and the increase was highly statistically significant (P = .0039). Analysis of the MT samples showed a decrease in osteoid percentage (mean osteoid percentage, 13.4%; SD, 2%) in the study group compared with the control group (mean osteoid percentage, 27.3%; SD, 3.5%). The decrease in osteoid percentage was statistically significant (P = .0001), indicating more rapid healing in the study group compared with the control group.

CONCLUSION

MSCs improved the bone quality of distracted bone and increased the crystal density in SEM images of the study group compared with that of the control group. MSCs showed promising results in improving the quality and quantity of distracted bone.

ETORPHINE-KETAMINE-MEDETOMIDINE TOTAL INTRAVENOUS ANESTHESIA IN WILD IMPALA (AEPYCEROS MELAMPUS) OF 120-MINUTE DURATION

There is a growing necessity to perform long-term anesthesia in wildlife, especially antelope. The costs and logistics of transporting wildlife to veterinary practices make surgical intervention a high-stakes operation. Thus there is a need for a field-ready total intravenous anesthesia (TIVA) infusion to maintain anesthesia in antelope. This study explored the feasibility of an etorphine-ketamine-medetomidine TIVA for field anesthesia. Ten wild-caught, adult impala ( Aepyceros melampus ) were enrolled in the study. Impala were immobilized with a standardized combination of etorphine (2 mg) and medetomidine (2.2 mg), which equated to a median (interquartile range [IQR]) etorphine and medetomidine dose of 50.1 (46.2-50.3) and 55.1 (50.8-55.4) μg/kg, respectively. Recumbency was attained in a median (IQR) time of 13.9 (12.0-16.5) min. Respiratory gas tensions, spirometry, and arterial blood gas were analyzed over a 120-min infusion. Once instrumented, the TIVA was infused as follows: etorphine at a variable rate initiated at 40 μg/kg per hour (adjusted according to intermittent deep-pain testing); ketamine and medetomidine at a fixed rate of 1.5 mg/kg per hour and 5 μg/kg per hour, respectively. The etorphine had an erratic titration to clinical effect in four impala. Arterial blood pressure and respiratory and heart rates were all within normal physiological ranges. However, arterial blood gas analysis revealed severe hypoxemia, hypercapnia, and acidosis. Oxygenation and ventilation indices were calculated and highlighted possible co-etiologies to the suspected etorphine-induced respiratory depression as the cause of the blood gas derangements. Impala recovered in the boma post atipamezole (13 mg) and naltrexone (42 mg) antagonism of medetomidine and etorphine, respectively. The etorphine-ketamine-medetomidine TIVA protocol for impala may be sufficient for field procedures of up to 120-min duration. However, hypoxemia and hypercapnia are of paramount concern and thus oxygen supplementation should be considered mandatory. Other TIVA combinations may be superior and warrant further investigation.

Determination of the minimum infusion rate of propofol required to prevent purposeful movement of the extremities in response to a standardized noxious stimulus in goats

OBJECTIVE

To determine the minimum infusion rate (MIR) of propofol required to prevent purposeful movement in response to a standardized stimulus in goats.

STUDY DESIGN

Prospective, experimental study.

ANIMALS

Eight healthy goats (four does, four wethers).

METHODS

Anaesthesia was induced with 4 mg kg(-1) propofol intravenously (IV). A continuous IV infusion of propofol at 0.6 mg kg(-1)  minute(-1) was initiated immediately to maintain anaesthesia. Following endotracheal intubation, goats breathed spontaneously via a circle breathing system delivering supplementary oxygen. The initial propofol infusion rate was maintained for 30 minutes before responses to noxious stimulation provided by clamping the proximal part of the claw with a Vulsellum forceps for 60 seconds were tested. In the presence or absence of purposeful movements of the extremities, the infusion rate was increased or reduced by 0.1 mg kg(-1)  minute(-1) and held constant for 30 minutes before claw clamping was repeated. The propofol MIR for each goat was calculated as the mean of the infusion rates that allowed and abolished movement. Basic cardiopulmonary parameters were monitored, recorded and tested for statistical significance using Wilcoxon's signed rank test with Bonferroni adjustment for multiple testing. The quality of recovery from anaesthesia was assessed and scored.

RESULTS

The median MIR of propofol was 0.45 mg kg(-1)  minute(-1) (range: 0.45-0.55 mg kg(-1)  minute(-1) ). Induction and recovery were free of adverse behaviour. No statistically significant cardiopulmonary changes in comparison with baseline were observed, but clinically relevant hypoxaemia at 2 minutes after induction of anaesthesia was consistently observed. Chewing during anaesthesia was observed in three goats. Median times to extubation and standing were 3 minutes (range: 2-6 minutes) and 10 minutes (range: 7-21 minutes), respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Propofol induction and maintenance of general anaesthesia minimally compromise cardiopulmonary function when oxygen is supplemented in goats.

Determination of the minimum infusion rate of alfaxalone during its co-administration with fentanyl at three different doses by constant rate infusion intravenously in goats

OBJECTIVE

To determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement of the extremities in response to standardized noxious stimulation during its co-administration with fentanyl at three different doses by constant rate infusion (CRI) intravenously (IV) in goats.

STUDY DESIGN

Prospective, blinded, randomized crossover, experimental.

ANIMALS

Eight healthy goats; four does and four wethers.

METHODS

For induction of anaesthesia, a bolus of fentanyl was administered at 0.005 mg kg(-1) (LFent), 0.015 mg kg(-1) (MFent) or 0.03 mg kg(-1) (HFent) followed by alfaxalone at 2.0 mg kg(-1) . For maintenance, the goats received alfaxalone at an initial infusion rate of 9.6 mg kg(-1)  hour(-1) and one of three fentanyl treatments: 0.005 mg kg(-1)  hour(-1) (LFent), 0.015 mg kg(-1)  hour(-1) (MFent) or 0.03 mg kg(-1) hour(-1) (HFent). The MIR of alfaxalone was determined during fentanyl CRI by testing for responses to stimulation (clamping on a digit with Vulsellum forceps) every 30 minutes. Some cardiopulmonary parameters were measured.

RESULTS

The alfaxalone MIR median (range) was 6.7 (6.7-8.6), 2.9 (1.0-6.7) and 1.0 (1.0-4.8) mg kg(-1)  hour(-1) during LFent, MFent and HFent, respectively. Alfaxalone MIR was significantly lower during MFENT and HFENT compared to LFENT. Significantly low oxygen haemoglobin saturation (SaO2 ) and arterial oxygen partial pressure (PaO2 ), observed 2 minutes into anaesthesia after all fentanyl treatments, were the most remarkable adverse cardiopulmonary effects observed. Recovery from anaesthesia was severely affected by high doses of fentanyl with excitatory behavioural signs predominant for up to 2 hours post-administration after MFent and HFent.

CONCLUSIONS AND CLINICAL RELEVANCE

Fentanyl reduces alfaxalone MIR in goats in a dose-dependent manner. Immediate oxygen supplementation after induction of general anaesthesia is recommended to prevent hypoxaemia. Doses of fentanyl equal to or greater than 0.015 mg kg(-1)  hour(-1) tend to be associated with severe excitatory behaviour and should be avoided when fentanyl is administered to goats.

Determination of the minimum infusion rate of alfaxalone during its co-administration with midazolam in goats

INTRODUCTION

The minimum infusion rate (MIR) of alfaxalone when co-administered with midazolam in goats was evaluated.

MATERIALS AND METHODS

Eight goats (four does and four wethers) were anaesthetised, on separate occasions, with alfaxalone at an initial dose of 9.6 mg/kg/hour combined with one of three midazolam treatments: a bolus of 0.1 mg/kg followed by constant rate infusion (CRI) of 0.1 mg/kg/hour (treatment LMID), 0.3 mg/kg followed by CRI of 0.3 mg/kg/hour (MMID), 0.9 mg/kg followed by CRI of 0.9 mg/kg/hour (HMID), intravenously. Responses to stimulation (clamping on the proximal part of one digit of the hoof with Vulsellum forceps for 60 seconds) were tested every 30 minutes. In the absence or presence of a response to stimulation, the infusion rate was reduced or increased by 1.9 mg/kg/hour. Alfaxalone MIR was calculated as the mean of the infusion rates that allowed and abolished movement. Cardiopulmonary parameters were measured.

RESULTS

Alfaxalone MIR was 6.7 (6.7-8.6) mg/kg/hour, 6.7 (4.8-6.7) mg/kg/hour and 2.9 (1.0-4.8) mg/kg/hour for LMID, MMID and HMID respectively. Cardiopulmonary function was minimally affected, with hypoxaemia observed two minutes into anaesthesia during all treatments. Recovery from anaesthesia was excitement-free.

CONCLUSIONS

Midazolam causes a dose-dependent reduction of alfaxalone MIR in goats. Oxygen supplementation is recommended during anaesthesia with alfaxalone and midazolam in goats.

Determination of the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement of the extremities in response to a standardised noxious stimulus in goats

OBJECTIVE

To determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement of the extremities in response to noxious stimulation.

STUDY DESIGN

Prospective, experimental.

ANIMALS

Eight healthy goats; four does and four wethers.

METHODS

Anaesthesia was induced with alfaxalone 3 mg kg(-1) intravenously (IV). A continuous IV infusion of alfaxalone, initially at 0.2 mg kg(-1)  minute(-1) , was initiated. Following endotracheal intubation the goats breathed spontaneously via a circle breathing circuit delivering supplementary oxygen. The initial infusion rate was maintained for 30 minutes before testing for responses. The stimulus was clamping on the proximal (soft) part of one digit of the hoof with Vulsellum forceps for 60 seconds. In the absence or presence of purposeful movement of the extremities, the infusion rate was reduced or increased by 0.02 mg kg(-1)  minute(-1) and held constant for 30 minutes before claw-clamping again. Alfaxalone MIR was calculated as the mean of the infusion rates that allowed and abolished movement. Cardio-respiratory parameters were measured. Recovery from general anaesthesia was timed and quality scored. Results are presented as median (range).

RESULTS

The MIR of alfaxalone was 0.16 (0.14-0.18) mg kg(-1)  minute(-1) or 9.6 (8.4-10.8) mg kg(-1)  hour(-1) . Induction of and recovery from anaesthesia were excitement-free. Cardio-respiratory changes were minimal, although compared to baseline HR increased, and at 2 minutes post-induction, (prior to oxygen supplementation), PaO2 decreased significantly from 84 (80-88) to 70 (51-72) mmHg [11.2 (10.7-11.7) to 9.3 (6.8-9.6) kPa]. Sporadic muscle twitches, unrelated to depth of anaesthesia, were observed during the period of general anaesthesia. Time (minutes) to sternal recumbency and standing were 4.0 (3.0-10.0) and 41.5 (25.0-57.0) respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone can be used for total intravenous anaesthesia (TIVA) in goats and is associated with minimal adverse effects. Oxygen supplementation is advised, especially when working at higher altitudes.

The effects of midazolam and butorphanol, administered alone or combined, on the dose and quality of anaesthetic induction with alfaxalone in goats

Goats are rarely anaesthetised; consequently, scant information is available on the efficacy of anaesthetic drugs in this species. Alfaxalone is a relatively new anaesthetic agent, of which the efficacy in goats has not yet been studied. In this study, the sedative and alfaxalonesparing effects of midazolam and butorphanol, administered alone or concomitantly, in goats were assessed. Eight clinically healthy goats, four does and four wethers, were enlisted in a randomised crossover manner to receive intramuscular sedative treatments consisting of saline 0.05 mL/kg, or midazolam 0.30 mg/kg, or butorphanol 0.10 mg/kg, or a combination ofmidazolam 0.30 mg/kg with butorphanol 0.10 mg/kg before intravenous induction of general anaesthesia with alfaxalone. Following induction, the goats were immediately intubated and the quality of anaesthesia and basic physiological cardiorespiratory and blood-gas parameters were assessed until the goats had recovered from anaesthesia. The degree of sedation, quality of induction and recovery were scored. When compared with saline (3.00 mg/kg), midazolam,administered alone or with butorphanol, caused a statistically significant increased level of sedation and a reduction in the amount of alfaxalone required for induction (2.00 mg/kg and 1.70 mg/kg, respectively). Butorphanol alone (2.30 mg/kg) did not cause significant changes in level of sedation or alfaxalone-induction dose. During induction and recovery, the goats were calm following all treatments, including the control group. Cardiorespiratory and blood gasparameters were maintained within clinically acceptable limits. The present study showed that midazolam, administered alone or combined with butorphanol, produces a degree of sedation that significantly reduces the dose of alfaxalone required for induction of general anaesthesia in goats, without causing any major adverse cardiorespiratory effects.