Anesthesia and humane euthanasia methods for king worm larvae (Zophobas morio).

A growing spotlight on insect welfare as research subjects, fodder for vertebrate animals, and patients for veterinarians highlights the need to establish humane euthanasia methods for these species. An insect of increasing commercial importance is the king worm (Zophobas morio), a type of darkling beetle larvae. The initial objective of this study was to determine if prolonged exposure to isoflurane would lengthen anesthetic recovery and lead to euthanasia. Larvae were exposed to isoflurane for 10 min, 40 min, 70 min, 190 min, 13 h, and 24 h (n = 10 for each treatment duration group), and time to recovery was subsequently monitored in room air. The second objective was to determine effectiveness of secondary euthanasia methods: injectable potassium chloride at 1 mg/g body weight (n = 5) and 3 mg/g body weight (n = 5) doses; immersion in 200 proof ethanol (n = 10), 10% buffered formalin (n = 10), and water (n = 10); and freezing at -18°C (n = 10). Prolonged exposure to isoflurane led to extended recovery times, but 100% mortality was not achieved. Submersion in ethanol and injection of potassium chloride at a 3 mg/g body weight dose resulted in 100% mortality. If these larvae are to be used as future food sources, a humane euthanasia method that preserves the ability to be consumed is required.

Physiologic responses of Cownose Rays following freshwater dips for treatment of capsalid monogeneans.

OBJECTIVE: Two Cownose Rays Rhinoptera bonasus were presented for management of a severe capsalid monogenean infection Benedeniella posterocolpa in a mixed species habitat at an aquarium. METHODS: A series of freshwater (FW) dips were elected to mitigate parasite resistance to praziquantel due to the endemic monogenean population in the system. A pretreatment blood sample was opportunistically obtained, and subsequent samples were processed due to development of clinical signs. RESULT: While the first FW dip was tolerated well and did not induce abnormal behavior, the second led to one individual presenting with tachypnea, pallor, and lethargy. Marked hematological abnormalities requiring medical intervention occurred in both individuals after the second dip. After treatment with elasmobranch Ringer's fluid therapy, sodium bicarbonate, prednisolone acetate, and vitamin E/selenium in the more severely affected ray, and elasmobranch Ringer's alone in the second ray, hematologic derangements and symptoms resolved. Hemoconcentration, hyperproteinemia, hyperlactatemia, and hyperglycemia were attributed to a stress response. A selective loss of urea after exposure to FW resulted in decreased plasma osmolality. CONCLUSION: Given the severity of the stress response and associated complications observed, hyposalinity treatments should be utilized with caution in this species. If this therapy is employed, the clinician is advised to be prepared to administer supportive care coinciding with the FW dip if necessary.