Evaluation of Parenteral Drugs for Anesthesia in the Blue Crab (Callinectes sapidus)

Abstract

The objective of this study was to evaluate the efficacy and safety of several parenteral anesthetics in blue crabs (Callinectes sapidus). Thirty-one animals were administered one or more of the following drugs by injection into the hemolymph (i.v.) through an arthrodial membrane: etomidate, ketamine, lidocaine, pentobarbital, propofol, tiletamine-zolazepam, xylazine, and ketamine-xylazine. A subset of crabs received intracardiac ketamine. Etomidate had no effect. Lidocaine effects were ultrashort (<3 min). Pentobarbital had prolonged inductions (2 min) and often caused violent excitement and poor anesthesia. Propofol induced light anesthesia accompanied by distress and limb autotomy. Inductions with ketamine, xylazine, tiletamine-zolazepam, and ketamine-xylazine were usually fast (<60 sec). Their anesthetic effects were generally very short (5-10 min) but predictable, smooth, and with good muscle relaxation. The latter two protocols induced a deep plane of anesthesia more consistently but also more significant bradycardia. Intracardiac ketamine injection was fatal in four of five crabs. In conclusion, the anesthetic protocols were considered unsuitable for prolonged anesthesia. However, if very short-term anesthesia is desired, then tiletamine-zolazepam or ketamine-xylazine is recommended. Further studies are indicated to identify a safe anesthetic protocol of longer duration in C. sapidus as well as in other crab species.

EFFICACY OF ALFAXALONE FOR INTRAVASCULAR ANESTHESIA AND EUTHANASIA IN BLUE CRABS (CALLINECTES SAPIDUS)

“…The median induction times observed in this study were comparable to those seen with other injectable anesthetic agents attempted in crustaceans, such as ketamine, xylazine, tiletamine-zolazepam, procaine, and lidocaine. 2,11,23,27 The lower dosages of alfaxalone used in this study (5 and 10 mg/kg) were inconsistent at producing adequate anesthesia, suggesting they are unsuitable for anesthetizing blue crabs.…”

“…Criteria for the evaluation of anesthesia stages were based on standards established by Gardner 11 and Morgan et al 21 and modified by Quesada et al 27 Induction of anesthesia was defined as the loss of a righting reflex when placed in dorsal recumbency and as the loss of a defensive or aggressive behavior exhibited by elevation of the claws when agitated. 11,21,27 Crabs were manually restrained while a 25-gauge needle attached to a 3-ml syringe was inserted through the arthrodial membrane between the abdominal and cephalothoracic body segments and advanced dorsally until hemolymph was obtained. Alfaxalone was slowly administered into the pericardial sinus.…”

“…3,5,15,32 Although numerous methods for the immobilization of crabs have been evaluated, including tricaine methanesulfonate (MS-222), clove oil, procaine, ketamine, xylazine, and propofol, most are considered unsatisfactory based on slow onset, inconsistent action, or distressful response. 11,21,23,27 Options for efficient, safe, and predictable methods of anesthesia are needed to improve handling, transport, and manipulation for research procedures and for sedation before physical euthanasia of blue crabs.…”

Therapeutic Review: Propofol and Fospropofol

“…Excitatory movements have been noted during induction of canvasbacks, however, this was not reported in mute swans (Cygnus olor), redtailed hawks, great horned owls, or common buzzards. 25,28,38,45 More commonly, excitatory central nervous system signs are seen during the recovery period from propofol anesthesia, and this has been reported in mute swans, red-tailed hawks, and great horned owls. 28,45 Transient excitatory movements in other species have been reported in blue crabs (Callinectes sapidus) and rabbits (post-fospropofol administration).…”

“…25,28,38,45 More commonly, excitatory central nervous system signs are seen during the recovery period from propofol anesthesia, and this has been reported in mute swans, red-tailed hawks, and great horned owls. 28,45 Transient excitatory movements in other species have been reported in blue crabs (Callinectes sapidus) and rabbits (post-fospropofol administration). 10,46 In most situations, propofol is not used solely as an anesthetic agent, but in conjunction with other agents in a balanced anesthetic protocol.…”