Invertebrates Flashcards
What happened in a study of 2PE and MS222 in HSC?
Parameters that decreased with both protocols?
2-PHENOXYETHANOL (2-PE) AND TRICAINE METHANESULFONATE (MS-222) IMMERSION ANESTHESIA OF AMERICAN HORSESHOE CRABS (LIMULUS POLYPHEMUS).
Archibald KE, Scott GN, Bailey KM, Harms CA.
J Zoo Wildl Med. 2019 Apr;50(1):96-106
Horseshoe crabs are osmoconfomers (osmolality matches surroundings)
Horseshoe crabs respond to hypoxia with a decreased blood pressure, heart rate, and gilling rate
Hemocyanin is the extracellular oxygen-carrying molecule and holds only one oxygen
The mechanism of 2-PE is unknown
Objective: Compare the effects of two immersion anesthetics, tricaine methanesulfonate (MS-222) at 1 g/L (buffered with sodium carbonate) and 2-phenoxyethanol (2-PE) at 2 mL/L, on horseshoe crabs.
Surgical anesthesia produced in 9/10 2-PE crabs and 7/10 MS-222 crabs
Parameters that decreased with both protocols: heart contractility, gilling rate, pCO2, blood pressure
Parameters that did not change with both protocols: heart rate, pH, pO2
Conclusions: Immersion in 2-PE or MS-222 produced anesthesia in American HSCs with clinically useful induction and recovery times.
Define semelparous as it pertains to GPO
What was the most common lesion in a retrospective of GPO mortality?
What parasite was found to cause branchitis? What is the treatment?
What common endosymbiotic mesozoan parasite was found in the renal sacs without inflammation?
RETROSPECTIVE REVIEW OF MORTALITY IN GIANT PACIFIC OCTOPUS (ENTEROCTOPUS DOFLEINI)
Kathryn E. Seeley, Leigh A. Clayton, Catherine A. Hadfield, Dillon Muth, Joseph L. Mankowski, Kathleen M. Kelly
J. of Zoo and Wildlife Medicine, 47(1):271-274 (2016)
Semelparous: one repro event before death- grow rapidly, die immediately after spawning
No acquired immune system, innate gets overwhelmed by poor water quality, increased bacterial loads, environ stressors
Most common lesion = ulcerations and erosions (most common on mantle or distal arms)
Two had coelomic fluid with spiral bacteria, peri-renal fluid, mineralization
Most common histologic lesions = inflammatory
Most GPOs with respiratory changes had branchitis and Ichthyobodo
Recommend monitoring siphoning effort and treat Ichthyobodo with metronidazole
Ocular lesions and renal dicyemids common
Renal dicyemids = endosymbiotic mesozoan parasite in renal sacs of many cephalopods
No inflammation associated w/ them
Summary: Branchitis was histologically evident in 14 octopuses, often in conjunction with (Ichthyobodo) or amoeba. Senescence, parasitism, and husbandry were all important contributors to mortalities.
How can death be defined for moon jellyfish following euthanasia?
Which salt is recommended for euthanasia of moon jellyfish for use in NMR?
What was observed with the other two salts in this study?
EVALUATION OF EUTHANASIA OF MOON JELLYFISH (AURELIA AURITA) USING SIMPLE SALT SOLUTIONS
Mary Doerr, Michael K. Stoskopf
J. of Zoo and Wildlife Medicine, 50(1):123-126 (2019)
Background:
- 3 neuro structures:
- Rhopalia: bell margin = pacemaker of bell contraction
- Motor nerve net = responsible for bell contraction
- Diffuse nerve net = relays signal to bell margin and rhopalia
- Ethanol and MS222 obscure results of NMR-spectroscopy-based metabolomics
- MgCl2 – used to immobilize echnioderms, cephalopods, coelenterates
- KCl – euthanasia of American lobsters
- MgSO4 – euthanize bivalve mollusks, gastropod mollusks, annelids
Key Points:
- MgCl2 at highest dose euthanized within 32 seconds without signs of distress
- KCl not suitable b/c nematocyst discharge and radial convulsing at lower concentrations + loss of tissue integrity during dissection
- MgSO4 failed to provide euthanasia
Conclusions: MgCl2 provides effective, rapid euthanasia in jellyfish
What type of weighted MRI image was best for visualizing internal organs of HSC?
Which organs were still not very well visualized?
MORPHOLOGICAL ASSESSMENT OF HORSESHOE CRABS (TACHYPLEUS TRIDENTATUS) BY USING MAGNETIC RESONANCE IMAGING
Kenji Kutara, Yumi Une, Yoshinobu Fujita
J. of Zoo and Wildlife Medicine, 50(3):742-748 (2019)
• T2 weighted gave best images (best tissue contrast)
• Muscles able to be distinguished but not muscles of legs (resolution too low)
• Liver and CV system not distinguished because isointense
Take Home Message: Use T2 weighted MRI to visualize internal organs of horseshoe crabs; does not do a good job at evaluating cardiovascular or liver
How is anesthetic induction defined in sea urchins?
What immersion anesthetic has been used to safely sedate and anesthetize sea urchins?
TRICAINE METHANESULFONATE (MS-222) SEDATION AND ANESTHESIA IN THE PURPLE-SPINED SEA URCHIN (ARBACIA PUNCTULATA)
Applegate Jr JR, Dombrowski DS, Christian LS, Bayer MP, Harms CA, Lewbart GA.
Journal of Zoo and Wildlife Medicine. 2016 Dec;47(4):1025-33.
Effective anesthesia in other aquatic invertebrates:
• Isoflurane in octopus and tarantulas
• Alfaxalone in blue crabs
• KCl and MgCl in other inverts
Sea urchin Anesthesia:
• Sedation: loss of righting reflex with retained tactile spine response
• Induction: loss of righting reflex, release from a vertical surface
• Anesthesia: loss of righting reflex and loss of tactile spine response.
• Recovery: voluntary return to oral recumbency
• MS-222 @ 0.4 g/L → sedation
• MS-222 @ 0.8 g/L → anesthesia
• More unplanned spawning than at lower dose
• Recovery time was not dose dependent
• Induction with MS-222 was faster than with KCl in other studies
• No mortalities
Describe the technique for intracoelomic injection/hemolymph collection in sea urchins.
What was observed in a PK study of enrofloxacin and metabolite ciprofloxacin in urchins by injection and immersion?
POPULATION PHARMACOKINETICS OF ENROFLOXACIN AND ITS METABOLITE CIPROFLOXACIN IN THE GREEN SEA URCHIN (STRONGYLOCENTROTUS DROEBACHIENSIS) FOLLOWING INTRACOELOMIC AND IMMERSION ADMINISTRATION
Phillips BE, Harms CA, Lewbart GA, Lahner LL, Haulena M, Rosenberg JF, Papich MG.
Journal of Zoo and Wildlife Medicine. 2016 Mar;47(1):175-86.
Intracoelomic administration / hemolymph collection: insert needle perpendicular through peristomal membrane lateral to mouth at edge of the test (exoskeleton)
• No adverse effects
• Measurement of ciprofloxacin metabolite was low and inconsistent
• Immersion Cmax occurred >9 hr after completion of treatment
• Both treatments exceeded MIC for Vibrio and Pseudomonas and other pathogenic bacteria for days
Conclusions: Treatment of 10 mg/kg intraceolomic every 5 days or immersion 10 mg/L every 3 days for 6 hr may be effective treatment for urchins.
Describe technique for collection of water vascular system fluid vs introcoelomic injection in sea stars.
What was observed in a PK study of enrofloxacin with intracoelomic vs immersion administration in sea stars?
Population pharmacokinetics of enrofloxacin in purple sea stars (Pisaster ochraceus) following an intracoelomic injection or extended immersion
Justin F. Rosenberg DVM; Martin Haulena DVM, MSc; Brianne E. Phillips DVM; Craig A. Harms DVM, PhD; Gregory A. Lewbart MS, VMD; Lesanna L. Lahner DVM, MPH; Mark G. Papich DVM, MS
American Journal of Veterinary Research November 2016, Vol. 77, No. 11, Pages 1266-1275
Background:
- Sea star = echinoderm
- Coelomic fluid, water vascular fluid system, and hemal fluid are 3 separate compartments
- Collection of water vascular system fluid: aboral aspect of limbs 1cm from distal tip, 27g needle/1ml syringe
- Intracoelomic injections – 27g needle on aboral surface at base of limb near junction w/ central disc
Key Points:
• Intraceolomic was higher levels (Cmax) and longer half life than immersion
• No adverse effects
• Enrofloxacin present for > 126 hours (stopped testing)
• Ciprofloxacin barely detectable after injection
• Not detectable in green urchins
• Other inverts can convert enro to cipro: Chinese mitten-handed crabs, giant freshwater prawns, ridgetail white prawns, Chinese shrimp
• No adverse effects
Conclusions: Intracoelomic administration of enrofloxacin in purple sea stars had higher levels than immersion.
What is the causative agent of aspergillosis in sea fans in the FL keys?
Aspergillus sydowii
What is the oxygen binding protein in most aquatic inverts? Which group generally lacks an O2 binding pigment?
Hemocyanin
Bivalves - Majority lack oxygen binding pigment, O2 dissolved directly into hemolymph; Except the Marine Ark Anadara trapezia (multiple hemoglobins)
Causative agent of Marteiliosis in bivalves?
Is this a reportable dz?
Marteiliosis (protist, paramyxida) aka Aber dz aka Aq dz aka digestive gland dz
Marteilia refringens (Eu, Americas)
Marteilia sydneyi (Aus)
Enters host via epithelium of palps and gills
Protozoa develop and proliferate in GI
IM host lifecycle - Probably copepods
Death generally May-Aug of second growth year
Causative agent of Bonamiosis in oysters?
Is this a reportable dz?
Bonamiosis (haplosporidian) AKA microcell disease, hemocyte disease, winter mortality
Disease of oysters – Flat oyster, Foveax Strait oyster, Ostrea denselammellosa
Associated with haplosporidians:
Bonamia ostreae
Bonamia exitiosus
Mikrocytos roughleyi
Very wide geographic range: NA, Europe, Australia
Profound economic losses
Mortalities up to 80%
Dual infection with other protozoa enhance mortality
Infection intensity greatest in females after spawning
Reportable by the OIE
CS: Discoloration of digestive gland, mantle, gills, decline in body condition
Dx via hemolymph smears, tissue imprints, histology
Bonamia organisms 2-5 microns in size
Heart tissue imprints
Massive tissue hemocyte infiltration
PCR, in situ hybridization for monoclonal antibodies
Combined use of heart tissue smears and PCR enhances sensitivity
Infection is contagious
Early harvesting at 15-18 months of production and subtidal culture may minimize impact
Breeding programs trying to produce Bonamia ostrea resistant oyster stocks
What are two reportable diseases of bivalves?
Marteilliosis (paramyxida), Bonamiosis (haplosporidian); Both protozoal dz
What compound is extracted from HSC for endotoxin detection in human medicine?
Limulus amebocyte lysate
What are the three body sections of HSC?
How are males distinguished from females?
Cephalothorax (prosoma), abdomen (opisthosoma), telson (tail)
Males have a single pair of modified chelicera - large bulbous claspers to grasp female
PK of enrofloxacin and ciprofloxacin in HSC?
Single injection 5 mg/kg in dorsal cardiac sinus lasted 120 hrs, no adverse effects, MIC reached.
Name three viruses of serious concern for shrimp culture.
Monodon Baculovirus
Infectious Hypodermal and Hematopoetic Necrosis Virus (parvo)
Taura Syndrome Virus (picorna)
What shrimp dz is highly prevalent in wild stocks in Indopacific basin and what are the primary clinical signs?
Monodon Baculovirus MBV
Shrimp culture regions in Indopacific basin
Highly prevalent in wild stocks
Most severe in post-larval stage (right after larval stage)
Primary CS:
Single or multiple occlusion bodies (type of inclusion body) in hepatopancreas and midgut epithelium
Seen on wet mounts
Histology – eosinophilic spherical bodies in nucleus of infected cells
Describe the inclusions observed with Infectious Hypodermal and Hematopoietic Necrosis Virus in shrimp.
Infectious Hypodermal and Hematopoietic Necrosis Virus
Americas and Asia
Affects juveniles
Acutely lethal to Litopenaeus stylirostris
Chronic infection in Litopenaeus vennamei
Dx with light microscopy
IHHNV produces Cowdry Type A inclusions
Eosinophilic nuclear inclusions (similar to herpesvirus)
Describe inclusions observed with Taura Syndrome Virus in shrimp.
Taura syndrome virus
Americas
Affects post-larvae, juveniles, and adults
Likely horizontal and vertical transmission
Mechanical transmission through insects and birds
Histology: Multifocal necrosis of cuticular epithelium with cytoplasmic inclusions
Lesions form grossly melanized foci
What is the causative agent of Gaffkemia in lobsters?
What is the only drug approved by the FDA to treat this dz?
Bacterial disease
Gaffkemia (red tail)
Aerococcus viridans var homari (gram positive tetrads)
Highly virulent for American lobsters, major losses 70s and 80s
Enters compromised integument -> Bacteremia
Low numbers of bacteria (5) sufficient for mortality 90% lobsters in 17 days
CS: severe lethargy, drooping tail, reddish color on ventrum
Hemolymph slow to clot
Gram stain hemolymph
Easily cultured
Control: Low temperature reduces severity, difficult to manipulate environment
Oxytetracycline is the only approved drug for tx of Gaffkemia, medicated feed
What is the causative agent of crayfish plague?
Is this dz reportable?
Crayfish plague
Aphanomyces astaci – water mold
Introduced into Europe in 1800s from new world
Usually 100% mortality
NA crayfish more resistant, can be carriers
Transmitted by motile spores that settle on and infect shells
Behavioral abnormalities
Hyperactivity followed by depression
Whitening of abdominal muscles
Hyphae visible in tissue with microscope
Requires live crayfish to survive, will die out otherwise
List 4 OIE reportable dz of shrimp.
What is an OIE reportable dz of crayfish?
Diseases notifiable to the OIE
Taura Syndrome Virus – penaeid shrimp
White spot disease – viral, penaeid shrimp, other decapods
Yellow head disease – viral, penaeid shrimp
Infectious Hypodermal and Hematopoietic Necrosis – viral, penaeid shrimp
White tail disease – viral, FW prawn
Crayfish plague – water mold, FW crayfish
What is the only drug approved for tx shrimp protozoan ectoparasites?
Formalin
What are the 4 coelomic circulatory systems in the basic echinoderm body plan?
Water vascular system
Perivisceral coelom (organs)
Hyponeural sinus system (nerves)
Genital coelom (gonads)
What was observed in a large mixed group of marine invertebrates exposed to copper?
Large mortality event – 441 marine inverts in mixed exhibit
Copper present at 22 mcg/L (below toxic levels previously reported)
Purple sea urchins used a sentinel species
CS, disease progression, pathology similar to original event
Death at 15-50 mcg/L
Source of copper toxicity ID as sand filters contaminated by brass pump components
What immersion tx is not recommended for echinoderms (causes aversive curling)?
Formalin
What virus has caused alarming episodes of oyster mortality in the Gulf of California?
Ostreid herpesvirus type 1 (OsHV-1)
Mainly affects larvae and juveniles
What is the causative agent of Dermo in oysters?
Which oyster spp is heavily impacted?
Perkinsus marinus (formerly Dermocystidium marinum)
Protozoan parasite similar to a dinoflagellate
Eastern oyster Crassostrea virginica, others
Distribution Eastern US around to gulf of Mexico. Chesapeake Bay extensive mortalities.
Infection most severe in summer - oyster immunity is reduced in higher temps
Focus on prevention and breeding more resistant oyster strains
Gold standard for routine surveillance is Ray’s fluid thioglycollate medium (RFTM) assay, but PCR and qPCR generally recommended.
What oyster dz is also known as MSX (multinucleated unknown or multinuclear sphere X), historically causing mortality in Chesapeake Bay?
Haplosporidium nelsoni
Pacific oyster Crassostrea gigas has been now bred for resistance to this dz. Also kills eastern oyster C. virginica.
What cell type is predominant in spider crabs?
What clin path changes were observed in spider crabs with exoskeletal lesions?
Differences between crabs that molted vs not?
How did ozone affect the hemocyte counts?
BASELINE HEMATOLOGIC AND BIOCHEMICAL VALUES AND CORRELATIONS TO ENVIRONMENTAL PARAMETERS IN MANAGED JAPANESE SPIDER CRABS (MACROCHEIRA KAEMPFERI)
Journal of Zoo and Wildlife Medicine 53(1): 173–186, 2022 Griffioen et al. TONS of DACZM
Semigranulocyte counts increased with exoskeletal lesion numbers, missing legs, No2 and NO3 (nitrogenous waste)
Exoskeletal lesions positively correlated with triglyceride values
Relative hyaline counts DECREASED with number of missing legs and NO3
Crabs w/ successful molting showed lower TP, cholesterol, triglycerides and amylase
No differences in hemocyte parameters related to molt
Blue swimmer crab and green crab have increased protein and lipid conc. during premolt phase
UV sterilization 🡪 Fewer exoskeletal lesions
Ozonation 🡪 lower granulocyte counts, and higher phosphorus, TP, albumin, globulin, Na and Cl
Strong positive correlation between hemolymph calcium and H2O calcium
Ca plays key role in molting process in crustaceans
Glucose, ALT, AST and LDH were very low to undetectable
Take-away: Study found important correlations between hemolymph values and environmental and life history data in HSC. Proper sample handling and processing (including temperature control; keeping samples cold) is very important.
Read this actual paper!
Describe hemolymph collection for hemocyte count and chemistry methods for spider crabs.
What is the main challenge to overcome?
First sample goes into lithium heparin tube
Second syringe with crustacean anticoag, transfer to plain cryovial
Every step must be kept as cold as possible
Hemocytometer for hemocyte counts
Hemolymph coagulation and microclotting still a huge issue; temp control (keeping everything cold) helpful
Prioritizing rapid sample processing to a formalin-fixed stable end point for hemocytes and keeping all sampling equipment as cold as possible provides the most valuable diagnostic sample.
Name the three types of cells in spider crabs
Which cells are more active in phagocytosis?
Hyaline cell (most common)
Semigranulocyte
Granulocyte (granules > 90% cytoplasm)
Hyaline cells and semigranulocytes appear more active in phagocytosis.
What was observed in a study evaluating MS222 for anesthesia of moon jellyfish (0.3 g/L vs 0.6 g/L immersion)?
What was observed in a low dose vs high dose group during induction?
Which test was more reliable for response evaluation? Probe somatosensory test vs rocking test?
MS-222 produces anesthesia-like effects (i.e., immobility and lack of response to stimuli) in aquatic invertebrate species, including horseshoe crabs, purple-spined sea urchin, and the 11-armed sea star
For this study, jellyfish were immersed in MS-222 for max time of 15 min
In the LC group, 8/8 jellyfish had bell fasciculations and uncoordinated pulsing during induction
May be similar to stage II anesthesia in mammals and fish (excitatory involuntary movement)
Not observed in HC group
2/8 animals in LC group did not reach threshold drug effect after 15 min
They did have delayed reaction time, mild to moderately flattened bells, and less complete pulses
Probe somatosensory test (PST - poke them with a probe see if they respond) was more reliable for response evaluation than rocking test (RT - tilt a bucket see if they return to normal position when put back down). Some jellyfish didn’t care about the RT even if they were not exposed to MS-222.
All reacted strongly to the PST initially, but no to very delayed response w/ MS-222 immersion
Many jellyfish would not react to RT even prior to being immersed in MS-222
Bell contraction quality and body were also useful for evaluating jellyfish response to MS-222
Demonstrating relaxed bells and decreased or absent pulses after drug exposure
Jellyfish in the HC group had larger bell sizes after treatment compared with baseline
Suggests state of significant relaxation associated with exposure to MS-222
No sig. change in bell size with LC group
One jellyfish in each group had mild responses to tag implantation - implications of reactions are unclear
Despite buffering, MS-222 treatment saltwater for both groups was more acidic than untreated water
Take-away: MS-222 at 0.3 and 0.6 g/L decreased movement and responses to stimuli in moon jellyfish with no adverse reactions or mortalities. 0.6 g/L resulted in faster time to threshold drug response and longer recovery times than 0.3 g/L. Larger bell sizze with higher concentration.
Overall the probe somatosensory test, bell contraction quality, body tone, and bell size may be beneficial to use in other studies involving jellyfish responses to MS-222
List OIE reportable crustacean diseases (USDA website).
OIE Diseases - Crustaceans
Acute hepatopancreatic necrosis disease
Aphanomyces astaci (crayfish plague)
Decapod iridescent virus 1
Hepatobacter penaei (necrotising hepatopancreatitis)
Infectious hypodermal and hematopoietic necrosis virus
- Infectious hypodermal and hematopoietic necrosis virus (IHHNV) Emerging Risk Notice August 2020
- Infectious hypodermal and hematopoietic necrosis virus (IHHNV) Information Sheet August 2020
Macrobrachium rosenbergii nodavirus (white tail disease)
Taura syndrome virus
White spot syndrome virus
Yellow head virus genotype 1
List OIE reportable disease of mollusks (USDA website).
OIE Diseases - Mollusks
Abalone herpesvirus
(abalone viral ganglioneuritis) aka haliotid herpesvirus 1
Bonamia exitiosa
Bonamia ostreae
(haplosporidians)
Marteilia refringens
(protist, paramyxida)
Perkinsus marinus
Perkinsus olseni
(protist, alveolate, similar to dinoflagellate)
Xenohaliotis californiensis
(rickettsial bacteria)
A recent study described hemolymph collection in emperor scorpions.
How were they restrained?
- How effective was it?
- How long did recovery take?
- How did this differ from other scorpion species?
Describe hemolymph collection in this species
- What was the colleciton site?
- How much hemolymph was collected?
- What is hemolymph?
- Describe its role in the scoprion circulatory system.
JZWM 2022 53(3) 573-577
HEMOLYMPH COLLECTION AND ISOFLURANE ANESTHESIA OF THE EMPEROR SCORPION (PANDINUS IMPERATOR)
Abstract: With captive invertebrates increasing in popularity, a safe and effective anesthesia protocol is required for their veterinary care. This study investigated the safety and efficacy of 5% isoflurane anesthesia and 0.26 ml hemolymph collection in subadult to adult emperor scorpions (Pandinus imperator; n = 14). Each scorpion was placed in a 2-L anesthetic chamber and induced with 5% isoflurane at a flow rate of 2 L/min oxygen. Anesthetic depth was assessed by rolling the animal into dorsal recumbency and rating the response from one to four: 1 = successful coordinated righting movement, 2 = successful uncoordinated righting movement, 3 = unsuccessful righting movement, 4 = no movement. Ratings 3 and 4 were both adequate for the hemolymph collection. The mean induction time was 4.2 min to reach a level 3 depth and 10.5 min to reach a level 4 depth. All animals were clinically normal for at least 1 yr post experiment. A mean hemolymph volume drawn of 1.92% of body weight, and an anesthetic induction with 5% isoflurane, appear safe in subadult to adult emperor scorpions.
Intro
- Background anatomy info:
– Scorpions are segmentally divided into the prosoma, mesosoma, and metasoma.
– The semiclosed circulatory system is composed of a dorsosagitally located heart in the mesosoma.
– The contractions of the heart, in conjunction with body and appendage movement, circulates the hemolymph and its constituents (e.g., hemocytes, nutrients, dissolved gasses)
- Hemolymph interacts with the respiratory system for gas exchange at four pairs of book lungs located on the ventral surface of tergites 10–13 in the emperor scorpion.
- Each book lung is an invagination of the exoskeleton, creating a cave-like antrum with an external opening called the spiracle. Within each antrum are thin parallel sheets of tissue lamellae for gas exchange with the hemolymph
- The objective of this study was to determine if anesthesia with 5% isoflurane, followed by 0.26 ml hemolymph collection, is a safe and effective protocol for subadult to adult emperor scorpions.
M&M
- n=14 subadult to adult emperor scorpions
- The scorpion was placed in a 2L anesthesia chamber on 5% isoflurane (O2 flow 2L/min)
- The scorpions were challenged at 30-s intervals by rotating the chamber 908 and attempting to roll the animal into dorsal recumbency.
- At each interval, the animal’s response to stimuli was rated on a scale of one to four: 1 = successful coordinated righting movement, 2 = successful uncoordinated righting movement, 3 = unsuccessful righting movement, 4 = no movement.
- The anesthetic gas was turned off after the animal had three consecutive time points at a rating of 4 or at 30 min, whichever came first
- A pericardial hemolymph sample was collected: at the dorsal midline, between mesosoma (abdomen) tergites five and six, a volume of 0.26 ml was collected.
- Each scorpion was placed in a plastic container with a screened top for room-air recovery.
- During recovery, all scorpions were challenged every 30 s and rated on the same response scale as used for anesthetic induction.
- The scorpions were considered recovered after three consecutive ratings of 1
Results
- The average time to a rating of 3 was 4.2 min and rating 4 being 10.5 min
- The five scorpions that did not receive a rating of 4 were nonetheless considered at an anesthetic plane safe enough for hemolymph collection after 30 min
- The average time to recovery for all scorpions, following discontinuation of anesthetic gas, was 12.7 min
- The average hemolymph drawn as a percent of body weight was 1.92%
- Hemolymph collection was possible in all scorpions, and no obvious signs of distress were noted during induction or recovery
- All scorpions alive 1 year post study
Discussion
- This study considered a rating of 3 or 4 safe for minor procedures such as hemolymph collection
- A previous study showed 5% isoflurane anesthesia in Asian forest scorpions was effective, however during sedation a dangerous hyperexcitatory phase was observed
- This was contrasted by the dictator scorpions (Pandinus dictator) in the same study having a smooth induction, similar to the emperor scorpion in the current study
- This may mean that scorpions in the same genus, Pandinus, have similar induction reactions to 5% isoflurane
- Importantly, differences in average induction time and recovery may suggest extrapolation between genera or species within Scorpiones is of limited value.
Takeaway: This study shows that hemolymph collection up to 1.92% of body weight and anesthesia with 5% isoflurane up to 30 min does not noticeably impact behavior or survival in subadult to adult emperor scorpions
A recent study investigated KCl, lidocaine, and ivermectin as potential euthanasia agents in anesthetized blue crabs.
What are the euthanasia guidelines for invertebrates?
What are the mechanisms of each of these euthanasia agents:
- KCl?
- Lidocaine?
- Ivermectin?
How were these animals anesthetized?
- What side effects occurred?
How did each of the euthanasia agents perform in this study?
Journal of Zoo and Wildlife Medicine 53(4): 689–695, 2022
EVALUATION OF INTRACARDIAC ADMINISTRATION OF POTASSIUM CHLORIDE, IVERMECTIN, OR LIDOCAINE HYDROCHLORIDE FOR EUTHANASIA OF ANESTHETIZED BLUE CRABS (CALLINECTES SAPIDUS)
Alissa B. Mones, DVM, Ashlyn C. Heniff, BS, Craig A. Harms, DVM, PhD, Dipl ACZM, Dipl ECZM (ZHM), and Julie A. Balko, VMD, Dipl ACVAA– Rev by AJC
Abstract: Methods to anesthetize and euthanize aquatic invertebrates have proven unreliable in decapods; thus studies to optimize euthanasia techniques for crustaceans are needed. Study objectives were to evaluate efficacy of intracardiac potassium chloride (KCl), ivermectin, or lidocaine hydrochloride (HCl) for euthanasia of anesthetized blue crabs (Callinectes sapidus). Twenty adult male crabs (n = 5/group) were immersed in 500 mg/L eugenol for 5 min 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 hydrochloride (HCl) (20 mg/ml), or 5 ml/kg saline (0.9%). 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/or recovery were recorded. Median (range) time to loss of righting reflex was 32 (17–57) min. One crab in all groups, except lidocaine HCl, 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 HCl, and saline, respectively. Median (range) time to Doppler sound cessation was 30 (0–55), 18 (16–28), and 50 (0–90) s in KCl, ivermectin, and lidocaine HCl groups, respectively. Tonic limb movements were observed in 5/5 KCl-treated crabs. Median (range) time to recovery was 180 (115–345) and 300 m in four saline-treated crabs and one lidocaine HCl–treated crab, respectively. Intracardiac KCl at 10 mEq/kg and ivermectin at 5 mg/kg were effective, rapid methods for euthanasia of anesthetized blue crabs.
Key Points:
- Euthanasia should be rapid, painless, reliable, and irreversible; minimize fear and distress
- Euthanasia guidelines for aquatic inverts consists of 2 step method, with the second step to destroy brain or major ganglia physically or chemically
- KCl: increases extracellular K and raises resting membrane potential of cardiac myocytes -> inactivates Na channel and stops myocardial cell depolarization -> cardiac arrest & neuronal hypoxia
- KCl has been given near CNS in inverts to cause death by targeted depolarization of neuronal cells
- Ivermectin 🡪 binds glutamate gates chloride channels 🡪 nervous system dysfunction
- Lidocaine 🡪 blocks voltage gated Na channels to block action potential propagation
- 500 mg/L eugenol immersion used for anesthetic induction 🡪 ~30 min to loss of righting reflex
– One crab in all groups except lidocaine had no doppler sounds prior to injection 🡪 narrow therapeutic index
– Doppler sounds ceased in 4/4 crabs in both KCl and ivermectin groups.
– 1 crab in lidocaine group and all saline injected recovered
– Time to cessation of doppler sounds was fastest in ivermectin injected > KCl > lidocaine
- Regurgitation occurred in 5 crabs during eugenol immersion – may need fast time > 12hr
– Gastric prolapse and vomiting reported in amphibians anesth with eugenol
- Tonic contraction of swimmerets and intermittent movement of chelipeds and limbs noted after injection of KCl and lasting up to 2 mins after doppler cessation.
- Ivermectin has strong affinity to lipid, soil, and organic matter 🡪 potential for relay toxicity
Take Home:
- Intracardiac KCl and ivermectin resulted in reliable, rapid loss of doppler sounds in anesthetized blue crabs - considered effective for euthanasia.
- Lidocaine was unreliable
