Evaluation of Intracardiac Administration of Potassium Chloride, Ivermectin, and Lidocaine Hydrochloride for Euthanasia of Anesthetized Blue Crabs (Callinectes sapidus)
Abstract
Crustaceans are commonly maintained under human care in research and aquarium settings.1 Methods to anesthetize and euthanize aquatic invertebrates have proven unreliable in decapods, thus, studies to optimize euthanasia techniques for crustaceans are needed.2–6 Study objectives were to evaluate efficacy of intracardiac KCl, ivermectin, or lidocaine hydrochloride for euthanasia of anesthetized blue crabs (Callinectes sapidus). Twenty adult male crabs (n=5/group) were immersed in eugenol 500 mg/L for five minutes beyond loss of the righting reflex and then randomly administered intracardiac 10 mEq/kg KCl (333 mg/mL), 5 mg/kg ivermectin (10 mg/mL), 100 mg/kg lidocaine (20 mg/mL), or 5 mL/kg 0.9% saline. Serial heart rate assessments were made using a Doppler probe placed over the dorsum and times to loss of righting reflex, Doppler sound cessation, and recovery were recorded. Median (range) time to loss of righting reflex was 32 (17–52), 30 (17–45), 32 (17–57), and 32 (15–42) minutes in KCl, ivermectin, lidocaine, and saline groups, respectively. One crab in all groups, except lidocaine, had no detectable Doppler sounds prior to injection. In the remaining crabs, Doppler sound cessation occurred in 4/4, 4/4, 4/5, and 0/4 crabs administered KCl, ivermectin, lidocaine, and saline, respectively. Median (range) time to Doppler sound cessation was 30 (0–55), 18 (16–28), and 50 (0–90) seconds in KCl, ivermectin, and lidocaine groups, respectively. Tonic limb movements were observed in 5/5 KCl-treated crabs. Intracardiac KCl 10 mEq/kg and ivermectin 5 mg/kg were effective, rapid methods for euthanasia of anesthetized blue crabs.
Acknowledgements
The authors thank Ashlyn Heniff for technical support and Ronald Harms for providing crabs for the study.
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