The effect of urethane and MS-222 anesthesia on the electric organ discharge of the weakly electric fish Apteronotus leptorhynchus.

Urethane and MS-222 are agents widely employed for general anesthesia, yet, besides inducing a state of unconsciousness, little is known about their neurophysiological effects. To investigate these effects, we developed an in vivo assay using the electric organ discharge (EOD) of the weakly electric fish Apteronotus leptorhynchus as a proxy for the neural output of the pacemaker nucleus. The oscillatory neural activity of this brainstem nucleus drives the fish's EOD in a one-to-one fashion. Anesthesia induced by urethane or MS-222 resulted in pronounced decreases of the EOD frequency, which lasted for up to 3 h. In addition, each of the two agents caused a manifold increase in the generation of transient modulations of the EOD known as chirps. The reduction in EOD frequency can be explained by the modulatory effect of urethane on neurotransmission, and by the blocking of voltage-gated sodium channels by MS-222, both within the circuitry controlling the neural oscillations of the pacemaker nucleus. The present study demonstrates a marked effect of urethane and MS-222 on neural activity within the central nervous system and on the associated animal's behavior. This calls for caution when conducting neurophysiological experiments under general anesthesia and interpreting their results.

ENDOSCOPIC REMOVAL OF A FOREIGN BODY IN A MEXICAN AXOLOTL (AMBYSTOMA MEXICANUM) WITH THE USE OF MS222-INDUCED IMMOBILIZATION.

This communication briefly describes the use of tricaine methanesulfonate (MS222) to induce chemical restraint/general anesthesia of a Mexican axolotl (Ambystoma mexicanum) for the endoscopic retrieval of a gastric foreign body. There is very little published scientific literature concerning the anesthesia of Mexican axolotls. The anesthesia used in this case was an immersion bath of tricaine methanesulfonate where the concentration of tricaine methanesulfonate was gradually increased to 500 mg/L (ppm) over a 15-min period. A loss of righting reflex was observed within 3 min of attaining the final concentration of the anesthetic bath. The first voluntary movements following the transfer to a freshwater bath occurred within 7 min. The recovery was uneventful. Tricaine methanesulfonate in this case proved to be an effective anesthetic agent for a short, minimally invasive procedure.

2-PHENOXYETHANOL (2-PE) AND TRICAINE METHANESULFONATE (MS-222) IMMERSION ANESTHESIA OF AMERICAN HORSESHOE CRABS (LIMULUS POLYPHEMUS).

Despite extensive literature examining American horseshoe crab physiology, there are comparatively few publications addressing their medical care. Establishing anesthesia protocols for horseshoe crabs is integral to limiting the potential stress and pain associated with invasive procedures and for advancing euthanasia techniques. The objective of this study was to compare the effects of two immersion anesthetics, tricaine methanesulfonate (MS-222) at 1 g/L (buffered with sodium carbonate) and 2-phenoxyethanol (2-PE) at 2 mL/L, on horseshoe crabs. Twenty horseshoe crabs were assigned to one of two anesthetic treatment groups and individually anesthetized in natural seawater. Water quality, cardiac contractility, and hemolymph gas analytes were measured prior to anesthesia and at 30 min Animals were monitored via heart rate, gilling rate, and sedation score every 5 min until recovered. Transcarapacial ultrasonography was used to obtain heart rate, gilling rate, and percent fractional shortening. Light or surgical anesthesia was produced in 10/10 animals in the 2-PE group and 8/10 animals in the MS-222 group. There was no significant difference in sedation scores, induction time (median 15 min), or recovery time (median 20.5 min). Gilling rate and cardiac contractility decreased during anesthesia, whereas heart rate did not. Hemolymph pH and pO2 were not different among treatment groups or time points. Baseline pCO2 was higher than pCO2 at 30 min for both groups but significantly elevated only in the MS-222 group. This is attributed to increased activity during the handling of awake animals. Invasive blood pressure obtained via cardiac catheterization in two animals was markedly decreased during surgical anesthesia. In conclusion, 2-PE and MS-222 provided effective anesthesia with clinically useful induction and recovery times. 2-PE provided a subjectively more reliable and smoother anesthesia compared to MS-222.

A Simple Method Associated With Reduced Opioid Consumption After Total Knee Arthroplasty.

BACKGROUND: Most patients experience moderate to severe pain after total knee arthroplasty (TKA). We hypothesized that intraoperative treatment of cut bone surfaces with local anesthetic (preimplantation immersion anesthesia, PIA) would lead to decreased postoperative pain and opioid consumption. METHODS: Records of 76 patients who underwent unilateral, cemented TKA were retrospectively reviewed. For PIA patients, surgical wounds were immersed in local anesthetic solution immediately prior to component implantation. Both PIA (n = 43) and control (n = 33) groups received multimodal pain management, including intra-articular local anesthetic injections. Endpoints were opioid consumption and mean pain scores for postoperative day (POD) 0, 1, and 2. Demographic, medical, and social factors were included in multivariate analyses. RESULTS: PIA patients reported significantly lower mean pain scores than controls on PODs 0 and 1 (both P < .005). Pain scores on POD 2 were similar. PIA patients used 45%-33% less opioids on PODs 0, 1, and 2 (all P < .005). POD 0 pain scores showed a significant interaction between PIA treatment and preoperative opioid use (P = .013). On POD 1, PIA was the only factor associated with lower mean pain scores (P < .001). No factors were significant for POD 2. PIA was the only factor associated with lower postoperative opioid consumption on PODs 0 and 2 (both P < .005). For POD 1, PIA and increasing age (both P ≤ .005) were associated with lower postoperative opioid consumption. CONCLUSION: PIA was associated with significant reductions in opioid use and mean pain scores after TKA.

Oxidative and biochemical responses in Brycon amazonicus anesthetized and sedated with Myrcia sylvatica (G. Mey.) DC. and Curcuma longa L. essential oils.

OBJECTIVE: To investigate the effects of rapid anesthesia and long-term sedation with the essential oils (EOs) of Myrcia sylvatica (EOMS) and Curcuma longa (EOCL) on biochemical and oxidative parameters in matrinxã. STUDY DESIGN: Prospective, randomized, laboratory experiment. ANIMALS: A total of 72 matrinxã (Brycon amazonicus) adults weighing 404.8 ± 27.9 g were divided into eight groups of nine fish. METHODS: Biochemical and oxidative effects were investigated in plasma and tissues of matrinxã subjected to rapid anesthesia (5 minutes) or long-term sedation (360 minutes, simulating the practice of transport) with EOMS (200 µL L-1 and 10 µL L-1, respectively) and EOCL (500 µL L-1 and 40 µL L-1, respectively). RESULTS: Transport simulation without sedation or anesthesia increased lipid peroxidation levels in the gills and kidney of fish in the control group. Anesthesia and sedation with EOs decreased cortisol concentrations and increased lactate concentrations compared with controls. Lipid peroxidation was lower in the brain, gills, liver and kidney of sedated and anesthetized fish, than in the control group. Anesthesia with EOs increased the activity of superoxide dismutase and glutathione-S-transferase in the brain, and catalase in the liver and gills, compared with controls. Long-term sedation with EOs increased superoxide dismutase, glutathione peroxidase and glutathione reductase activities in the brain, catalase in the liver, glutathione peroxidase and glutathione reductase in the gills and superoxide dismutase in the kidney. In general, nonprotein thiols content and total reactive antioxidant potential of tissues were higher after anesthesia and sedation with EOs compared with the control group. CONCLUSIONS AND CLINICAL RELEVANCE: The concentrations of EOMS and EOCL used were effective at preventing a stress response and excess of reactive oxygen species formation. For these reasons, these substances may be recommended for use in the transportation of fish to improve survival and animal welfare.

Celiotomia e gastrotomia para remoção cirúrgica de corpos estranhos em axolote (Ambystoma mexicanum): relato de caso / Celiotomy and gastrotomy for surgical removal of foreign bodies in axolotl (Ambystoma mexicanum): case report

A ingestão de corpos estranhos em aquários artificiais é uma ocorrência frequente observada na clínica cirúrgica de anfíbios criados como pets, o que inclui os axolotes (Ambystoma mexicanum). O presente relato descreve um caso de ingestão de sete corpos estranhos em um axolote macho, de cinco meses de idade, com histórico de abaulamento irregular e irredutível da superfície corpórea ventral, de consistência firme. Na anamnese foi informado que o animal habitava um aquário com substrato de cascalhos. Ao exame físico, o axolote apresentou bom estado geral e parâmetros vitais dentro da normalidade para a espécie. Os materiais deglutidos foram identificados em região gástrica por meio de exame radiográfico corpóreo total, e suas características condiziam com o substrato utilizado no aquário do paciente. Como protocolo anestésico, foi priorizada a imersão em Isofluorano e gás oxigênio, com o objetivo de atingir a via branquial e, ocasionalmente, transdérmica. A remoção cirúrgica foi feita através de celiotomia e gastrotomia em ambiente aquático com temperatura, pH e coleção bacteriana controlados, conforme literatura disponível e tendo em consideração a natureza, diâmetro e localização dos corpos estranhos. Após cinco e quinze dias do procedimento, acompanhou-se a cicatrização da ferida cirúrgica, sendo possível constatar bom restabelecimento da continuidade dos tecidos e bom estado geral do paciente.

The ingestion of foreign bodies in artificial aquariums is a frequent occurrence observed in the surgical clinic of amphibians raised as pets, which includes axolotls (Ambystoma mexicanum). The present report describes a case of ingestion of seven foreign bodies in a male axolotl, five months old, with a history of irregular and irreducible bulging of the ventral body surface, with firm consistency. In the anamnesis, it was reported that the animal inhabited an aquariums with gravel substrate. On physical examination, the axolotl showed good general condition and vital parameters within the normal range for the species. The swallowed materials were identified in the gastric region by means of total body radiographic examination, and their characteristics were consistent with the substrate used in the patient's aquarium. As anesthetic protocol, immersion in Isofluorane and oxygen gas was prioritized, in order to reach the branchial and, occasionally, transdermal route. Surgical removal was performed through celiotomy and gastrotomy in an aquatic environment with controlled temperature, pH and bacterial collection, according to available literature and taking into account the nature, diameter and location of foreign bodies. After five and fifteen days of the procedure, the healing of the surgical wound was monitored, showing a good restoration of tissue continuity and a good general condition of the patient.

Celiotomia e gastrotomia para remoção cirúrgica de corpos estranhos em axolote (Ambystoma mexicanum): relato de caso / Celiotomy and gastrotomy for surgical removal of foreign bodies in axolotl (Ambystoma mexicanum): case report

A ingestão de corpos estranhos em aquários artificiais é uma ocorrência frequente observada na clínica cirúrgica de anfíbios criados como pets, o que inclui os axolotes (Ambystoma mexicanum). O presente relato descreve um caso de ingestão de sete corpos estranhos em um axolote macho, de cinco meses de idade, com histórico de abaulamento irregular e irredutível da superfície corpórea ventral, de consistência firme. Na anamnese foi informado que o animal habitava um aquário com substrato de cascalhos. Ao exame físico, o axolote apresentou bom estado geral e parâmetros vitais dentro da normalidade para a espécie. Os materiais deglutidos foram identificados em região gástrica por meio de exame radiográfico corpóreo total, e suas características condiziam com o substrato utilizado no aquário do paciente. Como protocolo anestésico, foi priorizada a imersão em Isofluorano e gás oxigênio, com o objetivo de atingir a via branquial e, ocasionalmente, transdérmica. A remoção cirúrgica foi feita através de celiotomia e gastrotomia em ambiente aquático com temperatura, pH e coleção bacteriana controlados, conforme literatura disponível e tendo em consideração a natureza, diâmetro e localização dos corpos estranhos. Após cinco e quinze dias do procedimento, acompanhou-se a cicatrização da ferida cirúrgica, sendo possível constatar bom restabelecimento da continuidade dos tecidos e bom estado geral do paciente.

The ingestion of foreign bodies in artificial aquariums is a frequent occurrence observed in the surgical clinic of amphibians raised as pets, which includes axolotls (Ambystoma mexicanum). The present report describes a case of ingestion of seven foreign bodies in a male axolotl, five months old, with a history of irregular and irreducible bulging of the ventral body surface, with firm consistency. In the anamnesis, it was reported that the animal inhabited an aquariums with gravel substrate. On physical examination, the axolotl showed good general condition and vital parameters within the normal range for the species. The swallowed materials were identified in the gastric region by means of total body radiographic examination, and their characteristics were consistent with the substrate used in the patient’s aquarium. As anesthetic protocol, immersion in Isofluorane and oxygen gas was prioritized, in order to reach the branchial and, occasionally, transdermal route. Surgical removal was performed through celiotomy and gastrotomy in an aquatic environment with controlled temperature, pH and bacterial collection, according to available literature and taking into account the nature, diameter and location of foreign bodies. After five and fifteen days of the procedure, the healing of the surgical wound was monitored, showing a good restoration of tissue continuity and a good general condition of the patient.