Anesthesia and Analgesia in Antarctic Fish: An Experimental Approach

Abstract

-It was studied in Antarctic fishes the anesthetic and/or analgesic actions of central depressors ketamine, fentanyl and thiopental as well as the local anesthetic benzocaine. The drugs were added to aerated marine water at temperatures of 1-1.5 C. Ketamine (15 mg/L) and fentanyl (50 g/L) failed in inducing anesthesia but caused a long lasting analgesia and sedation. Thiopental was required in doses of 100 mg/L to anesthetize the fishes, that is, about 30 times higher than the usual anesthetic dose for mammals. The anesthesia was long lasting, that is, 3-4 h, and difficult to control. One fish remained in a comatose state for four days with survival. Benzocaine in doses of 100 mg/L was successful in anesthetizing the fishes within 6-8 min, anesthesia lasting for 15-20 min, with a minor respiratory depression.Key Words: Antarctic fish; Nototheniidae; benzocaine; fentanyl; ketamine; thiopental; analgesia; anesthesia.RESUMO -Foi levado a efeito em peixes antárticos um estudo sobre as ações anestésicas e/ou analgésicas de depressores centrais ketamine, fentanyl e thiopental bem como do anestésico local benzocaina. As drogas foram adicionadas à água marinha aerada nas temperaturas de 1 a 1,5 o C. Ketamine (15 mg/L) e fentanyl (50 g/L) não induziram anestesia mas causaram demorada analgesia e sedação. Doses de 100 mg/L de Thiopental foram necessárias para anestesiar peixes, ou seja, em concentração 30 vezes maior do que a dose anestésica usual utilizada para mamíferos. A anestesia ocasionada nos peixes foi longa -de 3 a 4 horas -e difícil de ser controlada. Um dos peixes utilizados na experimentação permaneceu em estado de comatose por quatro dias com sobrevida. Benzocaina em doses de 100 mg/L foi eficiente para anestesiar peixes dentro de 6 a 8 minutos após a sua administração. A anestesia, neste caso, teve duração de 15 a 20 minutos acompanhada de pequena depressão respiratória.

Use of sodium bicarbonate as an inexpensive general anesthetic for juvenile red tilapia hybrids

“…Unanesthetized fish suffer tremendous amount of stress during catching, transporting or when submitted to manipulation and disturbance of its natural environment. The stress and pain have crucial effects on the physiological responses and biochemical profile, inducing endocrine and metabolic disturbance in the fish (Iwama et al 1989;Bruecker and Graham 1993;Yoshikawa et al 1994;Bastos-Ramos et al 1998). Recent research studies have suggested that fish are capable of pain perception (Sneddon 2012).…”

Experimental Xylazine-Ketamine Anesthesia in the Common Carp (Cyprinus carpio)

“…Ketamine in combination with fentanyl has induced anesthesia experimentally in Antarctic fish (Bastos-Ramos et al, 1998). Ketamine with xylazine will induce anesthesia in grey nurse sharks in 10-20 min for 10-20 min (Smith, 1992).…”

“…A fourth, untreated group served as a control. The doses of ketamine and xylazine were based on preliminary experiments conducted in the common carp, as well as on the literature (Smith, 1992, Bastos-Ramos et al, 1998. We measured time to anesthesia in the fish by observing cessation of voluntary swimming and loss of responses to pinching the skin with forceps and pricking the tail with a 22-gauge needle every 2-3 min (Smith, 1992, Bastos-Ramos et al, 1998Zahl et al, 2009).…”

“…Anesthesia in the fish was accompanied by loss of reaction to unpleasant stimuli and respi- ratory depression (Tables 1, 2). Depressed respiration is a common side effect of anesthetic agents in fish (Smith, 1992;Losey and Hugie, 1994;Bastos-Ramos et al, 1998;Meyer and Fish, 2008;Zahl et al, 2009). Because of the short duration (7-24 min) of immobility measured in the present study, we recommend the use of xylazine or ketamine alone only for shorter clinical procedures.…”

“…Because of the short duration (7-24 min) of immobility measured in the present study, we recommend the use of xylazine or ketamine alone only for shorter clinical procedures. Caution should be practiced when using either agent alone, as xylazine was reported to cause ventilatory collapse and convulsion (Smith 1992;Ross and Boss, 2008), and ketamine was not effective in inducing complete immobility (Smith 1992;Bastos-Ramos et al, 1998;Ross and Boss, 2008) in other fish species. Metabolic variations and species differences are important factors that contribute to differences in responses of fish to anesthetic agents (Bastos-Ramos et al, 1998;Meyer and Fish, 2008;Ross and Boss, 2008;Zahl et al, 2009).…”