Clinical Anesthesia and Analgesia in Fish

Fish have become a popular experimental model and companion animal, and are also farmed and caught for food. Thus, surgical and invasive procedures in this animal group are common, and this review will focus on the anesthesia and analgesia of fish. A variety of anesthetic agents are commonly applied to fish via immersion. Correct dosing can result in effective anesthesia for acute procedures as well as loss of consciousness for surgical interventions. Dose and anesthetic agent vary between species of fish and are further confounded by a variety of physiological parameters (e.g., body weight, physiological stress) as well as environmental conditions (e.g., water temperature). Combination anesthesia, where 2 anesthetic agents are used, has been effective for fish but is not routinely used because of a lack of experimental validation. Analgesia is a relatively underexplored issue in regards to fish medicine. However, recent studies have investigated opioid agents, nonsteroidal antiinflammatory drugs, and local anesthetics to determine their efficacy in minimizing pain and discomfort. The opioid morphine and the local anesthetic lidocaine do have significant effectiveness in reducing pain-related responses in rainbow trout (Oncorhynchus mykiss). Studies aimed at developing reliable analgesic protocols should explore a wide range of analgesic drug classes in several fish species.     

Comparative efficacy of tricaine methanesulfonate and clove oil for use as anesthetics in red pacu (Piaractus brachypomus)

OBJECTIVE: To compare the anesthetic efficacy and physiologic changes associated with exposure to tricaine methanesulfonate and clove oil (100% eugenol). ANIMALS: 15 adult cultured red pacu (Piaractus brachypomus). PROCEDURE: Fish were exposed to each of 6 anesthetic concentrations in a within-subjects complete crossover design. Stages of anesthesia and recovery were measured, and physiologic data were collected before and during anesthesia. RESULTS: Interval to induction was more rapid and recovery more prolonged in fish exposed to eugenol, compared with those exposed to tricaine methanesulfonate. The margin of safety for eugenol was narrow, because at the highest concentration, most fish required resuscitation. Mixed venous-arterial PO2 consistently decreased with anesthesia, while PCO2 consistently increased with anesthesia in all fish regardless of anesthetic agent. The increase in PCO2 was accompanied by a decrease in pH, presumably secondary to respiratory acidosis. Anesthesia was associated with increased blood glucose, potassium, and sodium concentrations as well as Hct and hemoglobin. Fish anesthetized with eugenol were more likely to react to a hypodermic needle puncture than fish anesthetized with tricaine methanesulfonate. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthesia induced with tricaine methanesulfonate or eugenol contributes to hypoxemia, hypercapnia, respiratory acidosis, and hyperglycemia in red pacu. Similar to tricaine methanesulfonate, eugenol appears to be an effective immobilization compound, but eugenol is characterized by more rapid induction, prolonged recovery, and a narrow margin of safety. Care must be taken when using high concentrations of eugenol for induction, because ventilatory failure may occur rapidly. In addition, analgesic properties of eugenol are unknown.     

Endoscopic sex determination and gonadal manipulation in Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi).

Seventeen Gulf of Mexico sturgeons (Acipenser oxyrinchus desotoi) underwent endoscopic sex determination, gonadal biopsy, and various reproductive surgeries as part of a conservation development plan. The fish were anesthetized with tricaine methanesulfonate (MS-222) buffered with sodium bicarbonate and maintained on a recirculating water anesthesia circuit. A 6-mm Ternamian EndoTip Cannula, placed through the ventral midline, midway between pectoral and pelvic fins, permitted the introduction of a 5-mm telescope. Swim bladder aspiration and CO2 insufflation of the coelomic cavity provided excellent observation. Second and third cannulae were placed under direct visual control, lateral and cranial or caudal to the telescope cannula. Sex determination was successfully performed in all fish; however, five of 17 sturgeons (29%) required endoscopic gonadal biopsy to confirm sex. Bilateral ovariectomy or orchidectomy was successfully performed in three males and four females. Unilateral ovariectomy and bilateral ligation of the müllerian ducts using an extracorporeal suturing technique was accomplished in an additional three females. No apparent morbidity was associated with the anesthesia or endoscopic surgery in any fish. The ability to safely perform minimally invasive reproductive surgery in fish may have important management and conservation benefits.     

Tropical fish medicine. Anesthesia in fish

1. Before using anesthesia in fish, check water quality parameters for tropical fish aquariums in the locality. 2. Monitor any changes in water quality that result from anesthetic administration, especially pH and alkalinity. Have adequate buffering agents available to counter these changes. 3. Use one or two preferred agents, and become familiar with the effects they produce. 4. Where possible, withhold food from fish for 24 hours prior to administration of the anesthetic agent. 5. Try to anesthetize a few fish in a group first as a test batch. Wait 12 to 24 hours for signs of delayed mortality before proceeding to anesthetize the rest of the fish. 6. Always provide adequate aeration in holding vessels. 7. Where practical, use water that the fish has come from in the anesthetic tank. 8. Always have a container of the same water for the fish to recover in.     

Nonlethal clinical techniques used in the diagnosis of diseases of fish

Numerous nonlethal clinical techniques can be used on live fish to yield valuable diagnostic information. These techniques include skin, fin, and gill biopsies; bacteriologic cultures of gill or skin lesions; tissue and fluid aspiration; and radiography Most techniques can be performed on live fish without the use of anesthesia, although light sedation of the fish often simplifies the procedure, making the procedure more easily accomplished and less stressful on the fish. Because water conditions have a considerable effect on the health and well-being of aquatic animals, an in-house evaluation of water quality (eg, temperature, pH, ammonia, nitrites, nitrates, and salinity) is also paramount to any clinical diagnostic evaluation. As with domestic animals, a complete and accurate history and thorough external examination are prerequisite to the selection of appropriate diagnostic techniques as well as the formulation of any management or therapeutic plan. Through the correlation of clinical history, water quality variables, and results of diagnostic testing, an informed plan of action can be devised to correct acute or chronic problems in aquatic animals.     

MRI of the live fish brain at 3 Tesla: Feasibility,technique and interspecies anatomic variations

Advances in aquatic animal medicine and continued growth of the fish hobbyist and aquaculture communities have led to a developing interest in antemortem diagnostic imaging of aquatic species. The aims of this prospective, pilot study were to determine whether advanced neuroimaging can be safely achieved in live fish using clinically available equipment, to optimize imaging parameters, and to develop a comparative MRI atlas of a few fish species of economic or research value. Two each of channel catfish (Ictalurus punctatus), koi (Cyprinus rubrofuscus), and grass carp (Ctenopharyngodon idella) of at least 30 cm in length were individually anesthetized for 3 Tesla (3T) magnetic resonance imaging (MRI) of the brain. All fish achieved an adequate anesthetic level for prolonged immobilization during imaging. Diagnostic quality images were obtained for all subjects; however, the spatial resolution was maximized with larger fish. Imaging protocols were optimized for standard neuroimaging sequences. Additionally, inversion times for fluid-attenuation inversion recovery (FLAIR) sequences were adapted to the naturally high protein content of fish pericerebral fluid. Following imaging, the fish successfully recovered from anesthesia, were humanely euthanized, and were immediately processed to assess brain histopathology. Necropsy confirmed the sex and health status of each fish. A limited comparative MRI atlas was created of the brains of these species for clinical reference. Findings from the current study supported the use of 3T MRI as an adjunct diagnostic test for fish with suspected neurologic disease and provided a limited anatomic atlas of the teleost brain for use as a reference.     

Surgery in fish.

Surgery in fish is feasible and practical for clinical and research applications. Certain adjustments in standard surgical procedures are necessary to accommodate piscine tissue handling, skin sensitivity, aqueous respiration, anatomic variations, and patient size. General considerations for fish surgery, including anesthesia, presurgical evaluation, equipment, suture selection, and surgical site preparation, have been presented here. Procedures described include celiotomy, enucleation, pseudobranchectomy, swim bladder surgery, gonadectomy, liver and kidney biopsy techniques, telemetry device implantation, and vascular catheterization.     

The efficacy of alfaxalone for immersion anesthesia in koi carp (Cyprinus carpio)

ObjectiveTo characterize the physiologic and behavioral effects of a single induction dose and two maintenance doses of alfaxalone delivered by water immersion in the anesthesia of koi (Cyprinus carpio).Study designProspective, within-subject complete crossover design.AnimalsSix adult koi (Cyprinus carpio) with a median body weight of 344.5 g (range 292.0–405.0 g).MethodsKoi were immersed in water containing 10 mg L^?1 alfaxalone until immobile and then maintained with alfaxalone at either 1 or 2.5 mg L^?1 via a recirculating water system. Times for anesthetic induction and recovery periods were recorded. Physiologic and blood gas parameters were evaluated before, during and after the anesthetic trial. Response to noxious stimuli was also assessed.ResultsMedian anesthesia induction time for all fish was 5.4 minutes. Median recovery time was 11.8 and 26.4 minutes in the 1.0 and 2.5 mg L^?1 doses, respectively, which were significantly different (p = 0.04). Cessation of opercular movement occurred in 0/6 and 4/6 fish exposed to 1.0 and 2.5 mg L^?1 dose respectively. No difference was observed in median heart rate over the duration of the anesthetic events. Response to noxious stimulation was 4/6 and 0/6 in the 1.0 and 2.5 mg L^?1 doses respectively. Oxygenation and ventilation did not change during the experiment, but there was a significant decrease in blood pH along with an increase in blood lactate concentration.Conclusion and clinical relevanceAdministration of alfaxalone, via water immersion, as an induction and maintenance anesthesia agent provided rapid and reliable anesthesia of koi with no mortality. The maintenance dose of 2.5 mg L^?1 was sufficient to prevent response to noxious stimuli but was associated with a clinically relevant depression in opercular rate.     

Anesthesia and anesthetic action mechanism of essential oils of Aloysia triphylla and Cymbopogon flexuosus in silver catfish (Rhamdia quelen)

Objectives

To document the time for anesthesia induction and recovery using different concentrations of essential oils (EOs) of Cymbopogon flexuosus and Aloysia triphylla in silver catfish (Rhamdia quelen), and to determine whether the mechanism of action of either EO involves the benzodiazepine (BDZ) site of the GABA_A receptor.

Essential oil of Aloysia citriodora Paláu and citral: sedative and anesthetic efficacy and safety in Rhamdia quelen and Ctenopharyngodon idella

ObjectiveTo verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish.Study designClinical study, randomized, parallel, multi-arm with control group in target species.AnimalsA total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used.MethodsSilver catfish and grass carp were exposed to different concentrations of citral, 15–675 and 15–600 μL L^–1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 μL L^–1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 μL L^–1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment.ResultsCitral only induced sedation from 15, 25 and 40 μLL^–1 in both species. Anesthesia without mortality was induced in silver catfish at 50–600 μL L^–1 and grass carp at 75–450 μL L^–1. At 675 and 600 μL L^–1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments.Conclusions and clinical relevanceCitral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.     

CASE REPORT: Iridociliary melanoma with secondary lens luxation: distinctive findings in a long‐horned cowfish (Lactoria cornuta)

This report describes a long‐horned cowfish, which was diagnosed with buphthalmia and lens sub‐luxation in the right eye, conditions that progressed to complete anterior lens luxation and secondary keratoconus. Three months after the initial evaluation, a pigmented mass was observed protruding from the vitreous. An enucleation was performed under general anesthesia. Ocular histopathology revealed an iridociliary melanoma. Reports of intraocular melanomas are extremely rare in fish. To the authors’ knowledge, this is the first report of an iridociliary melanoma that led to buphthalmia, lens luxation, and keratoconus in a fish. Histological findings of lens luxation are also demonstrated. Due to the presence of a complex suspensory apparatus involving the teleost lens, this report speculates that lens luxation is a more devastating disease process in teleosts than in mammals.     

Comparison between coelioscopy and coeliotomy for liver biopsy in channel catfish

Objective-To evaluate endoscopic liver biopsy and compare that technique with a standard coeliotomy biopsy technique in fish. Design-Randomized controlled clinical trial. Animals-30 channel catfish (Ictalurus punctatus). Procedures-10 fish were randomly assigned into control, coeliotomy, and coelioscopy groups. Anesthesia was performed with a recirculating anesthesia machine. Body weight, PCV, and total protein (TP) concentration in blood as well as plasma activities of aspartate aminotransferase, creatinine phosphokinase, lactate dehydrogenase, and sorbitol dehydrogenase were measured before and after surgery. Standard ventral coeliotomy or coelioscopy was performed, and the biopsy specimens were scored histologically. Results-Coeliotomy and coelioscopy procedures were well tolerated without acute deaths. Blood TP concentration and PCV decreased after surgery in the coelioscopy group because of intracoelomic fluid administration to aid visualization. Minor changes in activities for hepatic and muscular enzyme activities were apparent, but were not significantly different between the coelioscopy and coeliotomy groups. Coelioscopy and coeliotomy yielded biopsy specimens of similar diagnostic quality. However, coelioscopy permitted a more extensive evaluation of the viscera, and all 10 surgical wounds healed completely, compared with severe wound dehiscence in 3 of 10 fish that underwent coeliotomy. Conclusions and Clinical Relevance-Both coelioscopy and coeliotomy were capable of yielding antemortem liver biopsy specimens of diagnostic quality in catfish. Coelioscopy permitted a more detailed examination of the coelomic viscera through a smaller surgical incision, was less traumatic, and resulted in decreased wound dehiscence.     

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.

河豚毒素的研究进展

河豚毒素是最先从河鲀中分离提取得到的一种剧毒的生物碱类天然神经毒素,后来在包括水生和陆生的多种动物体中均有发现。河鲀正在成为福建省的一种重要养殖鱼类,药理研究也发现河豚毒素在治疗成瘾、癫痫、局部和全身麻醉及镇痛等方面发挥着重大的作用。河豚毒素的研究具有重要意义,但是河鲀体内河豚毒素的确切来源目前仍没有定论,其生物合成途径也尚待阐明。本文对河豚毒素理化性质、作用及来源等方面进行综述。     

Fish, amphibian, and reptile analgesia.

Pain perception and appropriate behavioral responses are important for survival. The conservation of the opioid ligand and receptor suggests evolution of opioid receptors mediating antinociception throughout vertebrate phylogeny. Fish, amphibians, and reptiles have appropriate neurologic components, display the appropriate behavior in response to a painful stimulus, and possess antinociceptive mechanisms to modulate pain. Because pain perception in these species is therefore likely to be analogous to that of mammals, invasive and painful procedures should always be accompanied by appropriate analgesia and anesthesia. Although specific doses have not been established in clinical trials, clinicians should attempt to provide lower vertebrates with appropriate analgesia during painful procedures. Further experimental and clinical investigations are necessary to expand the current veterinary literature in the area of pain and analgesia in lower vertebrates such as fish, amphibians, and reptiles.     

作用于钠通道受体的海产源神经毒素研究概况

阐述了几种重要的钠通道受体神经毒素,包括麻痹性贝毒、短裸甲藻毒素、西加毒素等的毒源、理化特性、毒理效应、临床症状及检测方法。麻痹性贝毒通过食物链传递而富集于石房蛤、贻贝、扇贝及某些蟹类体内,阻滞钠离子通透,造成神经系统传输障碍而产生麻痹作用。短裸甲藻毒素由短裸甲藻产生,与钠通道受体靶部位Ⅵ结合。西加毒素由岗比毒甲藻产生,通过食物链富集于海洋鱼类体内。与钠通道受体靶部位VI结合,激活钠通道,增加钠离子通透性。检测方法有鼠生物法, ELISA, 高效液相色谱法(HPLC)等。     

Communications: Blood Chemistry of Laboratory-Reared Golden Trout

Abstract

Golden trout Oncorhynchus aguabonita obtained from a wild stock as fertilized eggs were reared in the laboratory for 21 months. The laboratory-reared golden trout in our study reached sexual maturity earlier and grew more rapidly than wild golden trout do (according to the scientific literature). Male fish averaged 35.6 cm in total length and 426 g in weight, and females averaged 36.2 cm and 487 g. All golden trout were sexually mature when used for hematological analysis. The hematological profile (hematocrit, red blood cells, white blood cells, and thrombocytes) of golden trout was similar to that reported elsewhere for other trout species. Male and female golden trout did not have significantly different thrombocyte counts; however, the immobilization treatment used on the fish (anesthesia versus a blow to the head) resulted in significant treatment differences in thrombocyte numbers and interaction effect of sex in treatment for hematocrits. Gravid female golden trout had significantly higher plasma protein and calcium levels than did males. The ionic compositions of plasma (sodium, potassium, calcium, magnesium, copper, zinc, iron, and chloride) and gallbladder bile (calcium and chloride) were similar to those reported for other salmonids.     

S‐(+)‐Linalool from Lippia alba: sedative and anesthetic for silver catfish (Rhamdia quelen)

ObjectiveThe present study describes the isolation of linalool from the essential oil of Lippia alba (Mill.) N. E. Brown, and its anesthetic effect in silver catfish (Rhamdia quelen) in comparison with essential oil. The potentiation of depressant effects of linalool with a benzodiazepine (BDZ) and the involvement of GABAergic system in its antagonism by flumazenil were also evaluated.Study designProspective experimental study.AnimalsJuvenile silver catfish unknown sex weighing mean 9.24 ± 2.83 g (n = 6 for each experimental group per experiment).MethodsColumn chromatography was used for the isolation of S-(+)-linalool. Fish (n = 6 for each concentration) were transferred to aquaria with linalool (30, 60, and 180 μL L^?1) or EO of L. alba (50, 100, and 300 μL L^?1) to determine the induction time for anesthesia. After induction, the animals were transferred to anesthetic-free aquaria to assess their recovery time. To observe the potentiation, fish were exposed to linalool (30, 60, and 180 μL L^?1) in the presence or absence of BDZ (diazepam 150 μm). In another experiment, fish exposed to linalool (30 and 180 μL L^?1) or BDZ were transferred to an anesthetic-free aquaria containing flumazenil (5 μm) or water to assess recovery time.ResultsLinalool had a similar sedation profile to the essential oil at a proportional concentration in silver catfish. However, the anesthesia profile was different. Potentiation of linalool effect occurred only when tested at low concentration. Fish exposed to BDZ showed faster anesthesia recovery in water with flumazenil, but the same did not occur with linalool.Conclusions and clinical relevanceThe use of linalool as a sedative and anesthetic for silver catfish was effective at 30 and 180 μL L^?1, respectively. The mechanism of action seems not to involve the benzodiazepine site of the GABAergic system.     

Regional anesthesia as an adjunct for eyelid surgery in dogs

Eyelid surgery plays an important role in the management of a variety of ophthalmic diseases. Surgery on the adnexa and eye is routinely performed on an anesthetized patient. Minor procedures, such as conjunctival biopsy, may be performed in an awake patient using only topical anesthesia. Retrobulbar, peribulbar, and local anesthesia are less commonly used in general practice; however, they can provide significant advantages when used appropriately. Advantages to local anesthesia/sedation include being able to perform some ophthalmic procedures without having to place the patient under general anesthesia, ability to maintain the patient under a lighter plane of general anesthesia, improved postoperative comfort, and potentially smoother recoveries from general anesthesia. This article reviews this author's current indications and techniques for regional anesthesia as an adjunct to eyelid surgery in dogs.     

大鼠丘脑氨基酸类神经递质与塞拉嗪麻醉相关性

将32只Wistar大鼠随机分成4组,分别为对照组、麻醉组、恢复I组、恢复Ⅱ组。采用反向高效液相色谱法测定丘脑Glu、Asp、GABA和Gly的含量。结果显示,腹腔注射塞拉嗪40mg／kg后,麻醉组大鼠丘脑内GABA和Gly含量与对照组比较显著升高（P〈0．01）,Glu和Asp含量显著降低（P〈0．05或P〈0．01）;恢复I组丘脑Glu和Asp的含量与对照组比较差异显著（P〈0．05）;恢复Ⅱ组丘脑内GABA和Gly的含量与对照组比较差异显著（P〈0．05）,Glu和Asp的含量恢复显著（P〉0．05）。结果表明,塞拉嗪作用下引起丘脑内GABA、Gly、Glu和Asp含量的变化可能与塞拉嗪引起麻醉作用机制相关。