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.