Pharmacokinetics, plasma cortisol and effectiveness of benzocaine, MS-222 and isoeugenol measured in individual dorsal aorta-cannulated Atlantic salmon (Salmo salar) following bath administration

Abstract

During the life cycle as farmed animals there are numerous situations where fish are subjected to handling and confinement. Netting, weighing, sorting, vaccination, transport and, at the end, slaughter are common events under farming conditions. As research animals fish may also undergo surgical procedures, ranging from tagging, sampling, and small incisions, to larger operations. Under these varying situations treatment with anaesthetic agents might be necessary in order to ensure the welfare of the fish. Anaesthetic protocols for new species that are introduced to research or cultivation are generally based on protocols developed for the more established species. In Norway the anaesthetic protocols for Atlantic cod (Gadus morhua) and Atlantic halibut (Hippoglossus hippoglossus), which were introduced to fish farming in the 1980's, have thus been based on protocols used for salmonid species. Atlantic salmon (Salmo salar) has been farmed since the 1960's and is the most important species in Norwegian fish farming. The main objective of the current investigation was to gain more knowledge regarding the effect of anaesthetic agents in farmed fish, with special emphasis on Atlantic cod and Atlantic halibut. Large variations in response to anaesthetic agents exist both between and within fish species. Factors such as body weight, water temperature and acute stress may be important for the response and were studied in the current investigation. The anaesthetic agents benzocaine, metacaine (MS-222), metomidate hydrochloride, isoeugenol, 2phenoxyethanol, and quinaldine were used. In Atlantic cod and Atlantic halibut the agents were studied with regards to efficacy, assessed as induction and recovery times as well as reaction to handling under anaesthesia. In Atlantic salmon pharmacokinetic properties of the agents were examined. Both in Atlantic cod and Atlantic halibut large differences in efficacy between the different anaesthetic treatments were found. Induction and recovery times varied both in relation to body weight and in relation to water temperature. The main trend observed in Atlantic cod at high water temperature was shorter induction and recovery times for all weight groups and treatments. Whereas in Atlantic halibut higher water temperature resulted in shorter induction times, longer recovery times, and increased responsiveness to handling. Atlantic halibut of large body size displayed longer induction times, shorter recovery times, vi and reduced responsiveness to handling in comparison with fish of smaller body size. However, in Atlantic cod no uniform trend was found in the relationship between the size of the fish and anaesthetic efficacy. In Atlantic cod induction and recovery times were found to increase with increasing body weight for benzocaine and MS-222. For metomidate the recovery time increased with increasing weight whereas there were no weight related differences in induction time. No differences in either induction or recovery times associated to body weight were found for 2-phenoxyethanol. T...

Effects of anesthesia with the essential oil of Ocimum gratissimum L. in parameters of fish stress

“…Silver catfish exposed to EOO before handling had a better recovery profile of these parameters, as lower or similar concentrations were detected at 8 h compared to 0 h. A similar pattern was verified in the cortisol levels in Atlantic salmon following bath administration with benzocaine, MS-222, and isoeugenol. After 360 minutes, all the fish exposed to such anesthetics had similar or lower concentrations than those detected at time zero (Kiessling et al, 2009). …”

“…Stress response corresponds to an animal's attempt to maintain its homeostatic state (Barton, 2002;Kiessling et al, 2009). It involves the activation of neuroendocrine pathways, which promote catecholamine and corticosteroid (cortisol) release.…”

“…However, not all anesthetics used in aquaculture have an effect on inhibit the stress cascade and some induce cortisol responses (Kiessling et al, 2009;Zahl et al, 2010). For silver catfish (Rhamdia quelen), the fish species used in this study, anesthesia with eugenol and the essential oil of Lippia alba prevented plasma cortisol increase in fish submitted to air exposure (Cunha et al, 2010a, b).…”

“…Anesthetics are often used to reduce fish movement and stress during fish farming procedures (Kiessling et al, 2009). Stress response corresponds to an animal's attempt to maintain its homeostatic state (Barton, 2002;Kiessling et al, 2009).…”

Pharmacokinetics of propofol in rainbow trout following bath exposure

“…Anaesthetic influence on fish stress (Limsuwan et al 1983b, Olsen et al 1995 and biochemical and haematological indices (Gomułka et al 2008, Velisek et al 2006) have also been reported. There is a little information on the pharmacokinetics of anaesthetics in fish (Meinertz et al 1996, Stehly et al 1998, Guénette et al 2007, Kiessling et al 2009). …”