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American Journal of Veterinary Research Jun 2024To assess the efficacy of transmucosal euthanasia solution to induce euthanasia.
OBJECTIVE
To assess the efficacy of transmucosal euthanasia solution to induce euthanasia.
ANIMALS
6 bearded dragons (Pogona vitticeps).
METHODS
An initial dose of euthanasia solution containing pentobarbital and phenytoin sodium was administered transmucosally in conscious lizards (100 mg/kg pentobarbital dose), followed by a second dose 20 minutes later (400 mg/kg pentobarbital dose). The presence of movement, leakage of euthanasia solution, behaviors consistent with oral irritation, respiratory rate, heart rate, palpebral and corneal reflex, and response to noxious stimuli were recorded until death, confirmed by the absence of Doppler cardiac flow and cardiac electrical activity. The time to loss of all parameters was calculated. Postmortem evaluation allowed for histopathologic evaluation of the oral cavity and gastrointestinal tract to detect potential mucosal damage from the alkaline euthanasia solution.
RESULTS
The median time to death was 300 minutes (range, 300 to 360 minutes), median time to respiratory arrest was 30 minutes (range, 30 to 50 minutes), and median time to loss of deep pain response was 30 minutes (range, 20 to 50 minutes). Signs consistent with oral irritation occurred in 4 of 6 (66.7%) lizards, including 2 lizards that exhibited whole-body spasms after euthanasia solution administration. Histopathologic changes indicating peracute mucosal ulceration, suspected to be from caustic causes, were identified in 1 (1/6 [16.7%]) lizard.
CLINICAL RELEVANCE
Transmucosal euthanasia solution administration resulted in clinical euthanasia within 6 hours. This method should be utilized only after premedication with analgesic and/or anesthetic medications due to the potential for acute mucosal ulceration and behaviors that may be distressing in client-owned animals.
Topics: Animals; Phenytoin; Lizards; Pentobarbital; Euthanasia, Animal; Male; Female; Administration, Mucosal; Hypnotics and Sedatives
PubMed: 38569538
DOI: 10.2460/ajvr.24.02.0026 -
Annals of Surgery Jul 1990Hemodynamic and metabolic consequences of a 90-minute period of liver ischemia followed by 120 minutes of reperfusion were studied in rats that were awake during most of...
Hemodynamic and metabolic consequences of a 90-minute period of liver ischemia followed by 120 minutes of reperfusion were studied in rats that were awake during most of the experiment and in rats anesthetized with either pentobarbital (40 mg/kg body weight) or chloralose (30 mg/kg X hour) during the complete length of the experiment. Ischemia was induced by occluding the blood vessels to the left and median liver lobes with a small vascular clamp, which was removed after 90 minutes. Protein synthesis rate was determined by measuring incorporation rate of 14C-leucine into protein in incubated liver slices. At the end of the ischemic period, adenosine triphosphate levels in liver tissue and protein synthesis rate were reduced by 80% to 90%, with no significant differences among groups. During reperfusion, energy levels and protein synthesis rate remained depressed in the anesthetized animals, but improved, although not to normal values, in the awake rats. Hepatic tissue water increased during ischemia, probably reflecting hepatocellular membrane injury. The increase in hepatic tissue water was more pronounced in the chloralose group than in the other groups of rats. During reperfusion hepatic tissue water remained increased in the anesthetized rats but was normalized in the awake group. Mean arterial blood pressure was stable during ischemia and reperfusion in the pentobarbital anesthetized rats, while a progressive decrease in blood pressure during the experiment was noted in the chloralose group. The results suggest that hemodynamic and metabolic responses to liver ischemia and reperfusion can be influenced by anesthetics. Chloralose may be less suitable than pentobarbital for anesthesia when liver ischemia is inflicted.
Topics: Adenine Nucleotides; Animals; Chloralose; Hemodynamics; Ischemia; Liver; Male; Pentobarbital; Protein Biosynthesis; Rats; Rats, Inbred Strains; Time Factors
PubMed: 2363600
DOI: 10.1097/00000658-199007000-00004 -
BMC Veterinary Research Feb 2017The Canadian Council on Animal Care and American Veterinary Medical Association classify intraperitoneal (IP) pentobarbital as an acceptable euthanasia method in rats....
BACKGROUND
The Canadian Council on Animal Care and American Veterinary Medical Association classify intraperitoneal (IP) pentobarbital as an acceptable euthanasia method in rats. However, national guidelines do not exist for a recommended dose or volume and IP euthanasia has been described as unreliable, with misinjections leading to variable success in ensuring a timely death. The aims of this study were to assess and improve efficacy and consistency of IP euthanasia. In a randomized, blinded study, 51 adult female Sprague-Dawley rats (170-495 g) received one of four treatments: low-dose low-volume (LL) IP pentobarbital (n = 13, 200 mg/kg pentobarbital), low-dose high-volume (LH) IP pentobarbital (n = 14, 200 mg/kg diluted 1:3 with phosphate buffered saline), high-dose high-volume (HH, n = 14, 800 mg/kg pentobarbital), or saline. Times to loss of righting reflex (LORR) and cessation of heartbeat (CHB) were recorded. To identify misinjections, necropsy examinations were performed on all rats. Video recordings of LL and HH groups were analyzed for pain-associated behaviors. Between-group comparisons were performed with 1-way ANOVA and Games-Howell post hoc tests. Variability in CHB was assessed by calculating the coefficient of variation (CV).
RESULTS
The fastest euthanasia method (CHB) was HH (283.7 ± 38.0 s), compared with LL (485.8 ± 140.7 s, p = 0.002) and LH (347.7 ± 72.0 s, p = 0.039). Values for CV were: HH, 13.4%; LH, 20.7%; LL, 29.0%. LORR time was longest in LL (139.5 ± 29.6 s), compared with HH (111.6 ± 19.7 s, p = 0.046) and LH (104.2 ± 19.3 s, p = 0.01). Misinjections occurred in 17.0% (7/41) of euthanasia attempts. Pain-associated behavior incidence ranged from 36% (4/11, LL) to 46% (5/11, HH).
CONCLUSIONS
These data illustrate refinement of the IP pentobarbital euthanasia technique. Both dose and volume contribute to speed of death, with a dose of 800 mg/kg (HH) being the most effective method. An increase in volume alone does not significantly reduce variability. The proportion of misinjections was similar to that of previous studies.
Topics: Animals; Euthanasia, Animal; Female; Injections, Intraperitoneal; Pentobarbital; Rats; Rats, Sprague-Dawley
PubMed: 28222732
DOI: 10.1186/s12917-017-0982-y -
Anesthesiology Mar 1975Regional and cellular distribution of pentobarbital-14C in mouse brain was determined by frozen-section radioautographic methods. The mice were studied at the times of...
Regional and cellular distribution of pentobarbital-14C in mouse brain was determined by frozen-section radioautographic methods. The mice were studied at the times of loss (WRL) and return (WRR) of withdrawal response following a single intravenous dose of either 40 or 50 mg/kg body weight. At WRL, grey matter areas had higher concentrations of pentobarbital-2-14C than white matter. At WRR grey matter concentrations were not altered, but white matter areas were now similar to the grey. At WRL pentobarbital concentration was 55 per cent higher in large pyramidal cells in the parietal cortex than in surrounding neuropil. At WRL hippocampal pyramidal cell bodies (stratum pyramidalis) and glial cells in corpus callosum had pentobarbital levels similar to that of surrounding neuropil. Levels in the neuropil of these three areas were higher at WRR than at WRL. Lipid-rich compartments had higher pentobarbital concentrations at WRR than at WRL. The results suggest that return of consciousness after pentobarbital anesthesia is associated with intracerebral redistribution of pentobarbital even while there is continuing uptake into brain. (Key words: Brain, pentobarbital uptake; hypnotics, barbiturates, pentobarbital; pharmacokinetics, pentobarbital uptake.).
Topics: Absorptiometry, Photon; Animals; Autoradiography; Brain; Carbon Radioisotopes; Cerebral Cortex; Cerebrovascular Circulation; Corpus Callosum; Frozen Sections; Histocytochemistry; Male; Methylene Blue; Mice; Pentobarbital; Photomicrography; Staining and Labeling; Thalamus; Time Factors
PubMed: 46726
DOI: 10.1097/00000542-197503000-00005 -
Psychopharmacology 1980Pigeons were trained to discriminate the IM injection of pentobarbital (5 or 10 mg/kg) from saline in a task in which 20 consecutive pecks on one of two response keys...
Pigeons were trained to discriminate the IM injection of pentobarbital (5 or 10 mg/kg) from saline in a task in which 20 consecutive pecks on one of two response keys produced access to mixed grain. Pentobarbital (1.0--17.8 mg/kg) produced a dose-related increase in the percentage of the total session responses that occurred on the pentobarbital-appropriate key. The concomitant administration of bemegride (5.6--17.8 mg/kg) antagonized the discriminative control of behavior exerted by the training dose of pentobarbital. Benzodiazepines, diazepam (1.0 mg/kg) and clobazam (3.2 mg/kg), and barbiturates, methohexital (10 mg/kg), phenobarbital (56 mg/kg), and barbital (56 mg/kg), produced responding on the pentobarbital-appropriate key similar to that produced by pentobarbital. In contrast, narcotics such as morphine, ethylketazocine, cyclazocine, and SKF-10,047, at doses up to and including those that markedly suppressed response rates, produced responding predominantly on the saline-appropriate key. Similarly, the anticonvulsants, valproate, phenytoin, and ethosuximide occasioned only saline-appropriate behavior, indicating that not all anticonvulsants share discriminative stimulus effects with pentobarbital. Muscimol, a direct GABA agonist, and baclofen, a structural analogue of GABA, also failed to produce pentobarbital-appropriate responding. Ketamine, dextrorphan, and ethanol (0.3--3.2 g/kg, orally) produced intermediate levels of pentobarbital-appropriate responding, suggesting that the discriminative effects of these drugs may be somewhat like those of pentobarbital.
Topics: Animals; Baclofen; Bemegride; Columbidae; Ethanol; Muscimol; Pentobarbital; Prejudice; gamma-Aminobutyric Acid
PubMed: 6779321
DOI: 10.1007/BF00433247 -
Anesthesiology Sep 1981The effect of lidocaine, 160 mg/kg, and pentobarbital, 40 mg/kg, on cerebral oxygen and glucose consumption was examined at brain temperatures of 37 degrees C, 28...
The effect of lidocaine, 160 mg/kg, and pentobarbital, 40 mg/kg, on cerebral oxygen and glucose consumption was examined at brain temperatures of 37 degrees C, 28 degrees C, and 18 degrees C. Cerebral metabolic rate was measured in dogs on cardiopulmonary bypass circulation by using the sagittal sinus outflow technique. When studied separately, both drugs suppressed synaptic transmission and inhibited metabolism, and a maximum effect was obtained when the EEG became flat. Using halothane 1-1.5 per cent as the control condition, this function-metabolism coupled inhibition was about 30 per cent. When the drugs were studied in combination, it was found that when lidocaine was given after pentobarbital, it caused an additional metabolic inhibition of 15-20 per cent, while pentobarbital given after lidocaine had no effect. It is concluded that pentobarbital has no inhibitory effect on cerebral metabolism in the absence of synaptic activity, while lidocaine--in addition to the effect related to suppression of synaptic transmission--has a specific "membrane stabilizing" effect. In analogy to its local anesthetic action, lidocaine blocks the Na+ channels and restricts the Na+-K+ leak fluxes. The load on the ion pump is reduced and metabolism is decreased accordingly. This specific effect on lidocaine was evident also at brain temperatures of 28 degrees C and 18 degrees C. The study supports the possibility that lidocaine, like hypothermia, may provide protection for the ischemic brain.
Topics: Animals; Brain Ischemia; Cardiopulmonary Bypass; Dogs; Glucose; Hypothermia, Induced; Lidocaine; Oxygen Consumption; Pentobarbital
PubMed: 7270951
DOI: 10.1097/00000542-198109000-00013 -
Anesthesiology Jan 2000The acquisition of a conditioned eyeblink response has been used extensively to study the neurologic substrates of learning and memory. We examined the effects of the...
BACKGROUND
The acquisition of a conditioned eyeblink response has been used extensively to study the neurologic substrates of learning and memory. We examined the effects of the anesthetics isoflurane and pentobarbital, or hypothermia (30 degrees C), on the ability of rabbits to acquire an eyeblink conditioned response after 6.5 min of cerebral ischemia.
METHODS
New Zealand white rabbits (n = 48) were randomly assigned to sham, normothermic, hypothermic, isoflurane, or pentobarbital groups. In the normothermic, hypothermic, isoflurane, and pentobarbital groups, 6.5 min of global cerebral ischemia was produced. In animals randomized to the isoflurane and pentobarbital groups, a pattern of burst suppression was achieved on the electroencephalogram before the start of the ischemic episode. Animals in the hypothermia group were cooled to 30 degrees C before ischemia. Seven days after ischemia, eyeblink training was started using an audible tone presented for 100 ms as the conditioned stimulus. The unconditioned stimulus was an air puff directed at the cornea. The delay between the end of conditioned stimulus and the start of the unconditioned stimulus (the trace interval) was 300 ms in duration. A conditioned response was defined as an eyeblink that was initiated during the trace interval. Eighty trials per day and 15 days of training were delivered.
RESULTS
Neurologic deficits were greatest in the normothermia group, and these animals also had fewer conditioned responses than those in the sham, hypothermia, or pentobarbital groups. Animals in the isoflurane group had an intermediate number of conditioned responses that was not significantly different from the normothermia group.
CONCLUSIONS
This study demonstrates that a brief episode of cerebral ischemia results in the impairment of associative learning. Hypothermia and burst-suppressive doses of pentobarbital were able to improve neurobehavioral outcome as measured by ability to acquire a trace conditioned response.
Topics: Adjuvants, Anesthesia; Anesthetics, Inhalation; Animals; Brain Ischemia; Conditioning, Classical; Isoflurane; Male; Pentobarbital; Rabbits
PubMed: 10638914
DOI: 10.1097/00000542-200001000-00029 -
Anesthesiology May 1995Reductions in cerebral metabolic rate may increase the brain's tolerance of ischemia. However, outcome studies suggest that reductions in cerebral metabolic rate... (Comparative Study)
Comparative Study
BACKGROUND
Reductions in cerebral metabolic rate may increase the brain's tolerance of ischemia. However, outcome studies suggest that reductions in cerebral metabolic rate produced by anesthetics and by hypothermia may not be equally efficacious. To examine this question, we measured the effects of hypothermia, pentobarbital, and isoflurane on the cerebral metabolic rate for glucose (CMRG) and on the time to the loss of normal membrane ion gradients (terminal ischemic depolarization) of the cortex during complete global ischemia.
METHODS
As pericranial temperature was varied between 39 and 25 degrees C in normocapnic halothane-anesthetized rats, CMRG (using 14C-deoxyglucose) or the time to depolarization (using a glass microelectrode in the cortex) after a K(+)-induced cardiac arrest was measured. In other studies, CMRG and depolarization times were measured in normothermic animals (37.7 +/- 0.2 degrees C) anesthetized with high-dose pentobarbital or isoflurane (both producing burst suppression on the electroencephalogram) or in halothane-anesthetized animals whose temperatures were reduced to 27.4 +/- 0.3 degrees C. These three states were designed to produce equivalent CMRG values.
RESULTS
As temperature was reduced from 39 to 25 degrees C, CMRG decreased from 66 to 21 microM.100 g-1.min-1 (Q10 = 2.30), and depolarization times increased from 76 to 326 s. In similarly anesthetized animals at approximately 27 degrees C, CMRG was 32 +/- 4 microM.100 g-1.min-1 (mean +/- SD), whereas in normothermic pentobarbital- and isoflurane-anesthetized rats, CMRG values were 33 +/- 3 and 37 +/- 4 microM.100 g-1.min-1, respectively (P = 0.072 by one-way analysis of variance). Despite these similar metabolic rates, the times to depolarization were markedly different: for hypothermia it was 253 +/- 29 s, for pentobarbital 109 +/- 24 s, and for isoflurane 130 +/- 28 s (P < 0.0001).
CONCLUSIONS
The time to terminal depolarization is believed to be a measure of the rate at which energy stores are depleted. In this study there was a strong correlation between hypothermic reductions in CMRG and increases in the time to depolarization. This finding supports the belief that metabolic suppression may offer some cerebral protection. However, equivalent reductions in CMRG produced by hypothermia and by anesthesia were not equivalent in their effects on membrane failure. Whether hypothermia slows energy depletion by some unique mechanism or directly retards depolarization is unknown.
Topics: Animals; Brain; Brain Ischemia; Electroencephalography; Glucose; Hypothermia, Induced; Isoflurane; Male; Membrane Potentials; Pentobarbital; Rats; Rats, Sprague-Dawley
PubMed: 7741295
DOI: 10.1097/00000542-199505000-00015 -
Biological & Pharmaceutical Bulletin 2014The effects of inhalation anesthesia (2% isoflurane, sevoflurane, or enflurane) and intraperitoneal anesthesia with pentobarbital (65 mg/kg) were compared in rats... (Comparative Study)
Comparative Study
The effects of inhalation anesthesia (2% isoflurane, sevoflurane, or enflurane) and intraperitoneal anesthesia with pentobarbital (65 mg/kg) were compared in rats using an electrocardiogram (ECG) and determination of blood oxygen saturation (SPO2) levels. Following inhalation anesthesia, heart rate (HR) and SPO2 were acceptable while pentobarbital anesthesia decreased HR and SPO2 significantly. This indicates that inhalation anesthesia is more preferable than pentobarbital anesthesia when evaluating cardiovascular factors. Additionally, pentobarbital significantly increased HR variability (HRV), suggesting a regulatory effect of pentobarbital on the autonomic nervous system, and resulted in a decreased response of the baro-reflex system. Propranolol or atropine had limited effects on ECG recording following pentobarbital anesthesia. Taken together, these data suggest that inhalation anesthesia is suitable for conducting hemodynamic analyses in the rat.
Topics: Administration, Inhalation; Anesthesia, Inhalation; Animals; Atropine; Blood Pressure; Electrocardiography; Enflurane; Heart Rate; Hemodynamics; Injections, Intraperitoneal; Isoflurane; Male; Methyl Ethers; Oxygen; Pentobarbital; Propranolol; Rats; Sevoflurane
PubMed: 24790005
DOI: 10.1248/bpb.b14-00012 -
Experimental Animals 2012Pentobarbital (PB) and ketamine (Ket) influence the concentration of neurotransmitters in the brain. PB has been reported to decrease the extracellular nitric oxide (NO)...
Pentobarbital (PB) and ketamine (Ket) influence the concentration of neurotransmitters in the brain. PB has been reported to decrease the extracellular nitric oxide (NO) concentration through a decrease in acetylcholine (ACh) release, while Ket has been shown to increase the NO concentration via an increase in ACh release. Here, we investigated effects of PB and Ket on NO release and the relationship between NO and ACh in the rat striatum by in vivo microdialysis experiments. Male Sprague-Dawley rats were used. A microdialysis probe was inserted into the right striatum and perfused with modified Ringer's solution. Samples were collected every 15 min and injected into an HPLC system. The rats were freely moving, and PB and Ket were administered intraperitoneally. Neostigmine (1 and 10 µM) and mecamylamine (100 µM) were added to the perfusate. Calcium and magnesium concentrations were modified for each anesthetic to influence ACh release. PB decreased NO products (NOx) while Ket increased them. While perfusion with neostigmine showed no effect on baseline NOx concentrations, it diminished the PB-induced NOx reduction at low concentrations and abolished it at high concentrations. Magnesium-free perfusion had no effect on baseline NOx concentrations, whereas perfusion at a low magnesium concentration antagonized the PB-induced NOx reduction. Mecamylamine and calcium-free perfusion had no effect on baseline NOx concentrations and Ket-induced NOx increases. PB may decrease NO release through reduction in ACh release, whereas Ket may increase NO release independent of ACh regulation.
Topics: Acetylcholine; Animals; Cholinergic Neurons; Chromatography, High Pressure Liquid; Corpus Striatum; Excitatory Amino Acid Antagonists; Hypnotics and Sedatives; Injections, Intraperitoneal; Ketamine; Male; Mecamylamine; Microdialysis; Neostigmine; Nicotinic Antagonists; Nitric Oxide; Parasympathomimetics; Pentobarbital; Rats; Rats, Sprague-Dawley
PubMed: 22531732
DOI: 10.1538/expanim.61.165