An 18-µm microaggregate blood filter does not cause hemolysis during in vitro whole blood transfusions in sea turtles.

OBJECTIVE: Determine the hemolytic effect of an 18-µm microaggregate blood filter during in vitro sea turtle whole blood transfusions as well as describe the average diameter of leatherback (Dermochelys coriacea) and Kemp's ridley sea turtle (Lepidochelys kempii) RBCs. ANIMALS: 5 green (Chelonia mydas), 5 loggerhead (Caretta caretta), and 5 Kemp's ridley sea turtles (total n = 15). METHODS: Heparinized sea turtle blood was infused at 60 mL/h through a microbore extension set without and then with a postsyringe, inline 18-µm microaggregate blood filter. Pre- and postfiltration PCV, Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations were measured. With the use of light microscopy and archived blood smears, the maximum and minimum diameter of 20 RBCs from each of the 5 leatherback and 5 Kemp's ridley sea turtles were measured with a calibrated ocular micrometer using 400X magnification. RESULTS: There were no significant differences between pre- and postfiltration samples for Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations; however, there was a significant median postfiltration decrease in PCV of approximately 4%, representing a 13% decrease of the total RBCs transfused. Average maximum diameters for leatherback and Kemp's ridley sea turtle RBCs were 19.7 and 16.1 µm, respectively. CLINICAL RELEVANCE: Although the 18-µm microaggregate blood filter does not hemolyze transfused sea turtle RBCs and is likely safe for in vivo blood transfusions, the filter's pores may retain a small proportion of infused RBCs given their diameter.

Traumatic telson avulsion and attempted external stabilization in Atlantic horseshoe crabs (Limulus polyphemus).

Atlantic horseshoe crabs (Limulus polyphemus) are prevalent in public aquarium touch pools. Despite their popularity, the literature concerning medical management under managed care is sparse. Noninfectious conditions include trauma to the exoskeleton and compound eyes; however, injury to the soft tissue connecting the telson and opisthosoma has not been previously reported. This report describes telson avulsion in three Atlantic horseshoe crabs at a public aquarium and attempted external stabilization with a vascular silicone tie in two of three affected animals. The horseshoe crab that received no veterinary intervention suffered a complete telson amputation 1 month after the initial injury. Although the two other horseshoe crabs did well postoperatively, and external stabilization prevented further avulsion or amputation, they still could not right themselves if flipped into dorsal recumbency. All three horseshoe crabs were ultimately euthanized due to animal welfare concerns. To avoid potentially serious telson ligament injury, horseshoe crabs should never be picked up by the telson. The authors recommend that telson ligament injuries be addressed promptly, any inciting cause be mitigated, and external stabilization be considered earlier.

Diagnostic agreement between three point-of-care glucose and ß-hydroxybutyrate meters and reference laboratory methods in stingrays.

Point-of-care (POC) glucose and ß-hydroxybutyrate (ß-HB) meters can potentially provide rapid insight into an elasmobranch's metabolic state in clinical and field research settings. This study evaluated the diagnostic agreement of three commercial POC meters against reference laboratory methods for glucose and ß-HB concentrations in stingrays. Blood was collected during anesthetized exams from 28 stingrays representing four species: cownose rays (Rhinoptera bonasus), Atlantic stingrays (Hypanus sabina), southern stingrays (Hypanus americanus), and yellow stingrays (Urobatis jamaicensis). Glucose and ß-HB concentrations were measured with each POC meter using whole blood and plasma; in parallel, plasma glucose and ß-HB concentrations were measured via reference laboratory methods. Agreement between POC meters and reference laboratory methods was assessed using Bland-Altman methods, Passing-Bablok regression, observed total error, percent relative error, and linear mixed effect models. Plasma glucose and ß-HB concentrations determined by reference laboratory methods ranged from <20-63 mg/dL to 0.05-5.38 mmol/L, respectively. One human POC meter-the Precision Xtra-showed the greatest agreement with reference laboratory methods when measuring glucose with whole blood [mean bias and 95% CI: 0 (-3-4) mg/dL] and ß-HB with plasma [mean bias and 95% CI: 0.1 (-0.04-0.2) mmol/L]. Stingray sex, weight, buffy coat, and packed cell volume did not significantly affect the agreement between POC meters and reference laboratory methods. Across all three POC meters, mean bias and imprecision for plasma ß-HB concentrations were relatively small (0-0.1 mmol/L and 0%, respectively). Utilizing POC meters to measure glucose and ß-HB in stingrays may be viable when reference methods are unavailable.

Cutaneous epitheliotropic lymphosarcoma in a captive white catfish (Ameiurus catus Linnaeus).

A wild caught white catfish (Ameiurus catus Linnaeus) developed multiple cutaneous masses. Cytology revealed neoplastic lymphocytes and microscopy confirmed dermal infiltration with epitheliotropism in the epidermis, oral mucosa, and cornea, without internal organ involvement. Transmission electron microscopy did not identify viral particles. Histopathology supported cutaneous epitheliotropic lymphosarcoma, a condition most commonly reported in mammals. This is the first reported case of cutaneous epitheliotropic lymphosarcoma in an ictalurid and one of the few published cases of this condition in any fish species.

Transcriptome annotation reveals minimal immunogenetic diversity among Wyoming toads, Anaxyrus baxteri.

Briefly considered extinct in the wild, the future of the Wyoming toad (Anaxyrus baxteri) continues to rely on captive breeding to supplement the wild population. Given its small natural geographic range and history of rapid population decline at least partly due to fungal disease, investigation of the diversity of key receptor families involved in the host immune response represents an important conservation need. Population decline may have reduced immunogenetic diversity sufficiently to increase the vulnerability of the species to infectious diseases. Here we use comparative transcriptomics to examine the diversity of toll-like receptors and major histocompatibility complex (MHC) sequences across three individual Wyoming toads. We find reduced diversity at MHC genes compared to bufonid species with a similar history of bottleneck events. Our data provide a foundation for future studies that seek to evaluate the genetic diversity of Wyoming toads, identify biomarkers for infectious disease outcomes, and guide breeding strategies to increase genomic variability and wild release successes.

SAFETY OF MULTIPLE-DOSE INTRAMUSCULAR KETOPROFEN TREATMENT IN LOGGERHEAD TURTLES (CARETTA CARETTA).

Sea turtles are frequently presented for rehabilitation with injuries for which analgesic treatment is warranted. Ketoprofen is a nonsteroidal anti-inflammatory drug (NSAID) widely used in clinical veterinary medicine for musculoskeletal pain relief. Pharmacokinetics of 2 mg/kg IM have been studied in loggerhead sea turtles (Caretta caretta) as a single and a repeated dose q24hr for 3 days. Safety of longer term administration has not been performed, however, and NSAID use carries a risk of potential complications, including gastrointestinal ulceration, kidney damage, and bleeding. The objective of the current study was to determine the effects of a 5-day course of ketoprofen on thromboelastography (TEG) and hematological (including thrombocytes) and plasma biochemical analytes in loggerheads. A secondary objective was to determine 24-hr trough concentrations of ketoprofen after 5 days of treatment. Eight loggerheads were treated with ketoprofen 2 mg/kg IM q24hr for 5 days, and TEG, hematology, and plasma biochemistry panels were performed before and at the conclusion of treatment. Eight controls were treated with an equivalent volume of saline intramuscularly. Virtually no changes were detected before and after treatment or between treatment and control groups in any of the 24 endpoints evaluated, and marginal differences were not considered clinically relevant. Plasma ketoprofen concentrations after 5 days of treatment indicated no accumulation over that duration. Ketoprofen at 2 mg/kg IM q24hr for up to 5 days in loggerheads appears safe with respect to blood clotting and blood data, although other potential effects were not evaluated.

Molecular Assessment of Chelonid Alphaherpesvirus 5 Infection in Tumor-Free Green (Chelonia mydas) and Loggerhead (Caretta caretta) Sea Turtles in North Carolina, USA, 2015-2019.

Fibropapillomatosis is associated with chelonid alphaherpesvirus 5 (ChHV5) and tumor formation in sea turtles. We collected blood samples from 113 green (Chelonia mydas) and 112 loggerhead (Caretta caretta) turtles without fibropapillomatosis, including 46 free-ranging turtles (20 green turtles, 26 loggerheads), captured in Core Sound, North Carolina, and 179 turtles (93 green turtles, 86 loggerheads) in rehabilitative care in North Carolina. Blood samples were analyzed for ChHV5 DNA using quantitative polymerase chain reaction (qPCR), and for antibodies to ChHV5 peptides using an enzyme-linked immunosorbent assay (ELISA). None of the samples from foraging turtles tested positive for ChHV5 by qPCR; ELISA was not used for foraging turtles. Samples from 18/179 (10.1%) rehabilitating turtles tested positive for ChHV5 using qPCR, and 32/56 (57.1%) rehabilitating turtles tested positive for antibodies to ChHV5 using ELISA. Five turtles that tested positive by qPCR or ELISA at admission converted to being undetectable during rehabilitation, and five that initially tested negative converted to being positive. Both sea turtle species were significantly more likely to test positive for ChHV5 using ELISA than with qPCR (p < 0.001). There was no difference in the proportions of green turtles versus loggerheads that tested positive for ChHV5 using qPCR, but loggerheads were significantly more likely than green turtles to test positive for ChHV5 using ELISA. This finding suggests that loggerheads infected with ChHV5 at some point in their life may be more able than green turtles to mount an effective immune response against recrudescent infection, pointing to species-specific genetic differences in the two species' immune response to ChHV5 infection. This is the first study to analyze antibodies to ChHV5 in loggerhead turtles and represents the most complete dataset on ChHV5 DNA detection in sea turtles encountered in the more northern latitudes of their western Atlantic habitat.

EVALUATION OF LOCALIZED INFLAMMATORY REACTIONS SECONDARY TO INTRAMUSCULAR INJECTIONS OF ENROFLOXACIN IN STRIPED BASS (MORONE SAXATILIS).

Enrofloxacin is a fluoroquinolone widely used in animals including fish. Intramuscular (IM) injection of enrofloxacin is a feasible and efficacious option for drug delivery. In many species IM injection has been associated with injection site reactions and increases in serum muscle enzymes. Injection site reactions have not been well characterized in fish. Three groups of striped bass (Morone saxatilis) received an IM injection of enrofloxacin 2.27% in the right epaxial musculature 24, 48, or 96 hr prior to evaluation. Mean dose was 7.69 mg/ kg (6.14-9.69 mg/kg). The 24- and 48-hr groups received an injection of equal-volume 0.9% saline in the left epaxial musculature. A corresponding noninjected tissue sample was designated in the left epaxial musculature from each fish of the 96-hr group. Fish were euthanized and injection sites and noninjection control sites were evaluated grossly and histologically. Grades 1-4 were assigned to samples, with grade 1 corresponding to normal tissue and grades 2, 3, and 4 corresponding to mild, moderate, and severe inflammation and/or necrosis respectively. Externally, all control and injection sites appeared visually unremarkable. On cut surface, epaxial muscle of the enrofloxacin-injected tissue appeared moderately to severely hemorrhagic compared to saline and noninjected tissue, which was normal or mildly hemorrhagic. Histologically, eight of eight noninjected tissues were grade 1. For saline-injected tissues, 14 of 16 tissues were grade 2 and 2 samples were grade 3 when 24- and 48-hr groups were combined. For enrofloxacin-injected tissues, 8 of the 8 24-hr samples were grade 3 and 16 of the 16 48- and 96-hr samples were grade 4. These data show that IM injection of enrofloxacin 2.27% is associated with severe hemorrhage, necrosis, and inflammation in striped bass, and may negatively affect animal welfare.

Effective mydriasis in juvenile loggerhead turtles (Caretta caretta) following topical administration of rocuronium bromide and 10% phenylephrine.

OBJECTIVE: To determine the combined mydriatic effects of topical rocuronium bromide and phenylephrine in juvenile loggerhead turtles and identify any adverse effects associated with treatment. ANIMALS STUDIED: Eleven juvenile loggerhead turtles (Caretta caretta). PROCEDURES: Four 20 µL drops of rocuronium bromide and four 20 µL drops of 10% phenylephrine were placed into the right eye at 2-minute intervals of 5 turtles, while the same volume of saline was administered to six control turtles. A pupilometer recorded pupil measurements at rest and following a light stimulus at 2, 15, 30, 60, 120, 150, 180, 210, 240, 300, and 360 minutes following delivery of the final drop to the ocular surface. Intraocular pressure (IOP) was also measured at similar time points. RESULTS: The nonilluminated and light-stimulated pupillary diameter of the right eye of treated turtles was significantly greater than baseline starting at 120 and 15 minutes, respectively. Light-stimulated pupillary diameter of treated eyes was greater than that of control eyes from time 15 minutes until the end of the treatment period. No systemic side effects were noted over a 24 hours period following treatment and all turtles showed normal behavior and appetite. No mydriasis was noted in either eye at 24 hours and the anterior segment was normal. CONCLUSIONS: A combination of topical ophthalmic rocuronium bromide and 10% phenylephrine is safe and effective for mydriasis in juvenile loggerhead turtles.

Crude Oil and Dispersant Cause Acute Clinicopathological Abnormalities in Hatchling Loggerhead Sea Turtles (Caretta caretta).

Following the explosion of the Deepwater Horizon MC252 oil rig in 2010, 319 live sea turtles exposed to crude oil and oil-dispersant (Corexit) combinations were admitted to rehabilitation centers for decontamination and treatment. Treatment of oiled sea turtles was guided by expected physiological and pathological effects of crude oil exposure extrapolated from studies in other species and from a single loggerhead sea turtle (Caretta caretta) study. While invaluable starting points, inherent limitations to extrapolation, and small sample size of the experimental exposure study, reduce their utility for clinical guidance and for assessing oil spill impacts. Effects of dispersants were not included in the previous experimental exposure study, and cannot be effectively isolated in the analysis of field data from actual spills. A terminal study of pivotal temperature of sex determination using eggs salvaged from doomed loggerhead nests provided an opportunity for an ancillary exposure study to investigate the acute effects of crude oil, dispersant, and a crude oil/dispersant combination in sea turtle hatchlings. Eggs were incubated at 27.2-30.8°C, and hatchlings were randomly assigned to control, oil, dispersant, and combined oil/dispersant exposures for 1 or 4 days. Contaminant exposures were started after a 3 day post-hatching period simulating nest emergence. Turtles were placed in individual glass bowls containing aged seawater and exposed to oil (Gulf Coast-Mixed Crude Oil Sweet, CAS #8002-05-9, 0.833 mL/L) and/or dispersant (Corexit 9500A, 0.083 mL/L), replicating concentrations encountered during oil spills and subsequent response. Statistically significant differences between treatments and non-exposed controls were detected for PCV, AST, uric acid, glucose, calcium, phosphorus, total protein, albumin, globulin, potassium, and sodium. The principal dyscrasias reflected acute osmolar, electrolyte and hydration challenges that were more numerous and greater in combined oil/dispersant exposures at 4 days. Clinicopathological findings were supported by a failure to gain weight (associated with normal hatchling hydration in seawater) in dispersant and combination exposed hatchlings. These findings can help guide clinical response for sea turtles exposed to crude oil and crude oil/dispersant combinations, and indicate potential impacts on wildlife to consider when deploying dispersants in an oil spill response.

THE MESOPTERYGIAL VEIN: A RELIABLE VENIPUNCTURE SITE FOR INTRAVASCULAR ACCESS IN BATOIDS.

Intravascular access in batoid species is commonly achieved using the ventral coccygeal or radial wing vessels. However, these approaches can be difficult because of the presence of cartilage, lack of specific landmarks, species variation, and small vessel size in many species. This study used postmortem contrast radiography and gross dissection to develop landmarks for a new, dependable vascular access in three Myliobatiform species commonly maintained in captivity: Atlantic stingray (Hypanus sabinus), cownose ray (Rhinoptera bonasus), and smooth butterfly ray (Gymnura micrura). The mesopterygial vein provides quick vascular access and is suitable for administration of large fluid volumes and intravascular drugs. It is located immediately ventrolateral to the metapterygium cartilage, which sits adjacent to the coelomic cavity and supports the caudal half of the pectoral fin. Using the pectoral girdle and cranial third of the metapterygium cartilage as landmarks, vascular access can be achieved by directing a needle medially at approximately a 30° (adult cownose rays) or 45° angle (Atlantic stingrays, juvenile cownose rays, smooth butterfly rays) toward the metapterygium cartilage. Differences in the degree of needle direction are due to species and age-specific shapes of the metapterygium cartilage. The mesopterygial vein is an alternate site of quick and reliable venous access in batoid species.

Ophthalmic lesions in a population of cold-stunned sea turtles (Chelonia mydas, Lepidochelys kempii, Caretta caretta).

OBJECTIVE: To document ocular lesions present in cold-stunned sea turtles and determine the impact of these lesions on their release. ANIMALS: All sea turtles (Caretta caretta, Chelonia mydas, and Lepidochelys kempii) presenting to rehabilitation centers in North Carolina over two cold stun seasons. PROCEDURES: Complete ophthalmic examination using slit-lamp biomicroscopy, fluorescein stain, rebound tonometry, and occasionally binocular indirect funduscopy was performed within 1 week of presenting to the rehabilitation centers. A second examination was performed 2 weeks after the first examination in animals with ocular lesions and still present at the center. RESULTS: One hundred and sixty-four turtles (121 Chelonia mydas, 26 Lepidochelys kempii, 17 Caretta caretta) were evaluated over two cold stun seasons (2016-2017 and 2017-2018). Ocular or periocular lesions were identified in 78 of 164 (47.5%) turtles examined with 37 of 164 (22.5%) having bilateral disease. The most common ocular lesion was superficial corneal ulceration, accounting for 21.3% of all lesions. Adnexal lesions were also common, while intraocular abnormalities were overall rare. Most resolved uneventfully. Though some blinding lesions were noted, these were not present bilaterally in any one turtle, and thus, ocular findings did not affect release. CONCLUSION: Ocular lesions in cold-stunned sea turtles are common. Some of these lesions are potentially blinding or require appropriate care, so evaluation of cold-stunned turtles should include a complete ophthalmic examination.

Management and Case Outcome of Gastric Impaction in Four Raptors: A Case Series.

Four captive raptors, an American kestrel ( Falco sparverius ), peregrine falcon ( Falco peregrinus ), golden eagle ( Aquila chrysaetos ), and barn owl ( Tyto alba ), were diagnosed with ventricular and/or proventricular foreign material impactions consisting of artificial turf substrate, paper and plastic substrate, grass, and newspaper. Partial or total anorexia was reported in all birds and decreased casting in 2 birds. Survey radiographs confirmed presence of gastric enlargement in all 4 birds. The kestrel and eagle were treated unsuccessfully with gastroscopy and gastric lavage, respectively, followed by surgical intervention to remove the ventricular impactions. Both birds died of undetermined causes after surgery. The peregrine falcon died before medical or surgical intervention was started, and the owl was managed successfully with oral mineral oil and liquid diet to facilitate egestion of the foreign material as a pellet. Lead poisoning was suspected as the predisposing cause for foreign body ingestion in the eagle, but underlying causes for pica in the other birds were not determined. Radiographs can provide useful diagnostic information in sick raptors that exhibit vomiting or changes in appetite or casting frequency, and may help guide treatment decisions of impacted birds. Careful consideration of substrate, enrichment items, and access to potential foreign material that could be ingested may be the best pre-emptive management strategy in captive raptors.

Effects of alfaxalone administered intravenously to healthy yearling loggerhead sea turtles (Caretta caretta) at three different doses.

OBJECTIVE To compare physiologic and anesthetic effects of alfaxalone administered IV to yearling loggerhead sea turtles (Caretta caretta) at 3 different doses. DESIGN Randomized crossover study. ANIMALS 9 healthy yearling loggerhead sea turtles. PROCEDURES Animals received each of 3 doses of alfaxalone (3 mg/kg [1.4 mg/lb], 5 mg/kg [2.3 mg/lb], or 10 mg/kg [4.5 mg/lb]) administered IV in randomly assigned order, with a minimum 7-day washout period between doses. Endotracheal intubation was attempted following anesthetic induction, and heart rate, sedation depth, cloacal temperature, and respirations were monitored. Times to first effect, induction, first voluntary muscle movement, first respiration, and recovery were recorded. Venous blood gas analysis was performed at 0 and 30 minutes. Assisted ventilation was performed if apnea persisted 30 minutes following induction. RESULTS Median anesthetic induction time for all 3 doses was 2 minutes. Endotracheal intubation was accomplished in all turtles following induction. Heart rate significantly increased after the 3- and 5-mg/kg doses were administered. Median intervals from alfaxalone administration to first spontaneous respiration were 16, 22, and 54 minutes for the 3-, 5-, and 10-mg/kg doses, respectively, and median intervals to recovery were 28, 46, and 90 minutes, respectively. Assisted ventilation was required for 1 turtle after receiving the 5-mg/kg dose and for 5 turtles after receiving the 10-mg/kg dose. The 10-mg/kg dose resulted in respiratory acidosis and marked hypoxemia at 30 minutes. CONCLUSIONS AND CLINICAL RELEVANCE IV alfaxalone administration to loggerhead sea turtles resulted in a rapid anesthetic induction and dose-dependent duration of sedation. Assisted ventilation is recommended if the 10 mg/kg dose is administered.

Comparison of hematology, plasma biochemistry, and blood gas variables between 2 venipuncture sites in Southern Stingrays (Dasyatis americana).

BACKGROUND: The Southern Stingray (Dasyatis americana) is a batoid elasmobranch frequently exhibited in zoological institutions. Blood is commonly collected from the caudal hemal arch at the tail base in stingrays for the purpose of health assessment and clinical pathology tests. An alternative site that allows a dorsal or ventral approach without necessitating puncture of a cartilaginous structure has been identified between the cartilaginous pectoral fin rays (ceratotrichia). OBJECTIVES: The purpose of the study was to compare CBC, plasma biochemistry analytes, and blood gas variables between blood samples collected from the caudal and pectoral fin vasculature sites of the Southern Stingray. METHODS: Fifteen captive Southern Stingrays (10 females, 5 males) from 4 zoo and aquarium facilities were sampled. Lithium heparinized blood samples were collected from the caudal and pectoral venipuncture sites of each animal. Values from estimated total and differential leukocyte counts, plasma biochemistry analytes, and blood gas variables were compared. RESULTS: There were no statistically significant differences between venipuncture sites for the measured analytes except for CK activity, which was statistically significantly higher in the pectoral site samples. Levels of agreement between sites were good or moderate for 22 analytes and poor for ALT, AST, CK, pO2 , lactate, monocytes, and eosinophils. CONCLUSIONS: The good agreement between sampling sites for the majority of the measured analytes and the lack of differences that would alter clinical interpretation support the use of the pectoral site as an alternative to the traditional caudal fin venipuncture site in Southern Stingrays.

INFECTION OF A GOELDI'S MONKEY (CALLIMICO GOELDII) WITH A EUROPEAN STRAIN OF ECHINOCOCCUS MULTILOCULARIS IN A CANADIAN INSTITUTION.

A 12-yr-old female Goeldi's monkey (Callimico goeldii) in British Columbia, Canada was diagnosed with alveolar echinococcosis (AE) on postmortem examination. Echinococcus multilocularis has been identified in several species of nonhuman primates, most frequently Old World primates, in zoos and research facilities in Europe and Asia. The strain affecting this monkey was identified as a European haplotype, indistinguishable from E. multilocularis recently identified in several canids in British Columbia. The animal is suspected to have been exposed while living in a zoological institution in Alberta, where E. multilocularis has also been reported in urban coyotes. Alveolar echinococcosis is a zoonotic disease of increasing concern in the United States and Canada, and this disease should be considered on the differential list of any nonhuman primate exhibiting signs of abdominal pain or distension, along with diagnostic imaging consistent with cystic structures of the liver or other organs.

Underwater anesthesia of diamondback terrapins (Malaclemys terrapin) for measurement of auditory evoked potentials.

Investigations into the biology of aquatic and semiaquatic species, including those involving sensory specialization, often require creative solutions to novel questions. We developed a technique for safely anesthetizing a semiaquatic chelonian species, the diamondback terrapin (Malaclemys terrapin), for measurement of auditory evoked potentials while animals were completely submerged in water. Custom-modified endotracheal tubes were used to obtain a watertight seal on both sides of the glottis and prevent aspiration of water during testing. No adverse effects were seen after the procedures, and assessment of venous blood-gas partial pressures and lactate concentrations indicated that sufficient gas exchange was maintained under anesthesia through manual ventilation.

Efficacy of alfaxalone for intravascular anesthesia and euthanasia in blue crabs (Callinectes sapidus).

The objective of this study was to characterize the behavioral effects and changes in heart rate of four doses of alfaxalone delivered by intravascular injection to blue crabs (Callinectes sapidus). Thirty (male, n = 27; female, n = 3) blue crabs were randomly assigned to one of four treatment groups of alfaxalone: eight animals were assigned to each of the 5-, 10-, and 15-mg/kg treatment groups, and the remaining six animals were assigned to the 100-mg/kg group. Times for anesthetic induction and recovery periods were recorded. Righting reflex, defensive posturing, and heart rate were evaluated before, during, and after the anesthetic trial. Anesthesia was induced in all 14 animals consolidated into the high-dosage group (15 mg/kg [n = 8] and 100 mg/kg [n = 6]), which was significantly greater than 8 of 16 animals in the low-dosage group (5 mg/kg [n = 2] and 10 mg/kg [n = 6]). Median anesthesia induction time for all crabs was 0.4 min, with no significant difference in induction time between groups observed. Median recovery time was 9.4 min (n = 2), 6.1 min (n = 5), 11.3 min (n = 8), and 66.1 min (n = 5) for the 5-, 10-, 15-, and 100-mg/kg groups, respectively. Recovery times were significantly longer for crabs exposed to an induction dose of 100 mg/kg compared with the 10- and 15-mg/kg induction doses. A significant decrease in the median heart rate was observed between the baseline value and that observed at both induction and 5 min postinjection in the 100-mg/kg dose trial. Two mortalities were observed during the anesthesia trials (n = 1, 10 mg/kg; n = 1, 100 mg/kg), both associated with the autotomization of limbs. In summary, the intravascular administration of alfaxalone at 15 mg/kg provided rapid and reliable sedation, whereas alfaxalone administered at 100 mg/kg produced rapid and long lasting anesthesia.