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- Author or Editor: Matthew E. Kinney x
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Abstract
Objective—To determine the effects of μ-, δ-, and κ-opioid receptor (MOR, DOR, and KOR, respectively) activation on thermal antinociception in red-eared slider turtles Trachemys scripta.
Animals—51 adult turtles.
Procedures—Infrared heat stimuli were applied to the plantar surface of turtle hind limbs. Thermal hind limb withdrawal latencies (HLWLs) were measured before (baseline) and at intervals after SC administration of various doses of saline (0.9% NaCl) solution (SS), MOR, DOR, or KOR agonists (3 to 13 turtles/treatment). Treatment with a DOR antagonist SC prior to DOR agonist administration was also evaluated.
Results—Treatment with an MOR agonist ([D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin acetate salt [DAMGO; 1.3 or 6.6 mg/kg]) increased HLWLs (from baseline) at 2 to 8 hours after injection; at the higher dose, the maximum mean increase was 5.6 seconds at 4 hours. Treatment with a DOR agonist ([D-Ala2, D-Leu5]-enkephalin acetate salt [DADLE; 25 mg/kg]) increased mean HLWL by 11.3 seconds at 4 hours; however, treatment with DADLE (5.8 mg/kg) or with another DOR agonist ([D-Pen2,5]-enkephalin hydrate [DPDPE; 1.2 or 6.3 mg/kg]) did not alter HLWL, compared with SS effects. Administration of a DOR antagonist (naltrindole hydrochloride; 10 mg/kg) prior to DADLE administration (25 mg/kg) increased mean HLWL by 2.7 seconds at 4 hours. One KOR agonist, U50488 ([−]-trans-[1S,2S]-U50488 hydrochloride hydrate; 6.7 mg/kg) decreased HLWL steadily from 2 to 24 hours (less than baseline value); another KOR agonist, U69593 ([+]-[5α,7α,8β]-N-Methyl-N-[7-{1-pyrrolidinyl}-1-oxaspiro{4.5}dec-8-yl]-benzene-acet-amide; 6.7 or 26 mg/kg) did not alter HLWLs, compared with SS effects.
Conclusions and Clinical Relevance—Opioid-dependent thermal antinociception in turtles appeared to be attributable mainly to MOR activation with a relatively minor contribution of DOR activation.
Abstract
OBJECTIVE
To assess the pharmacokinetics and sedative effects of a single administration of oral gabapentin in African cheetahs (Acinonyx jubatus) at 2 different dosages.
METHODS
Adult cheetahs (n = 16) located at 3 different zoological institutions were prospectively enrolled to receive single doses of gabapentin administered at 2 different dosages (10 mg/kg and 20 mg/kg). Venipuncture was performed under behavioral restraint at predetermined time points over a 24-hour period using a sparse sampling model. Plasma concentrations of gabapentin were determined using high-performance liquid chromatography. A modified domestic felid sedation scoring system was used to assess animals at each time point by 3 masked scorers, and sedation scores were compared between time points.
RESULTS
Mean ± SE maximal plasma concentrations were 24.0 ± 12.8 μg/mL and 31.4 ± 8.57 μg/mL for the 10- and 20-mg/kg dosages, respectively. For both dosages, concentrations remained elevated at the final collection time point of 24 hours (2.39 ± 1.97 and 3.93 ± 3.09 μg/mL for 10 and 20 mg/kg, respectively). Mild sedation was achieved for both doses up to 24 hours postadministration, with no significant differences between dosages.
CONCLUSIONS
Gabapentin was well absorbed following oral administration, and concentrations remained elevated 24 hours postadministration. Gabapentin produces mild sedation at 10 or 20 mg/kg for up to 24 hours.
CLINICAL RELEVANCE
Gabapentin given to cheetahs at these dosages is a useful tool for improving patient welfare due to its mild sedative effects over a clinically relevant time period.
Abstract
OBJECTIVE
To determine the pharmacokinetics of a single bolus of intravenous (IV) propofol after intramuscular administration of etorphine, butorphanol, medetomidine, and azaperone in 5 southern white rhinoceros to facilitate reproductive evaluations. A specific consideration was whether propofol would facilitate timely orotracheal intubation.
ANIMALS
5 adult, female, zoo-maintained southern white rhinoceros.
PROCEDURES
Rhinoceros were administered etorphine (0.002 mg/kg), butorphanol (0.02 to 0.026 mg/kg), medetomidine (0.023 to 0.025 mg/kg), and azaperone (0.014 to 0.017 mg/kg) intramuscularly (IM) prior to an IV dose of propofol (0.5 mg/kg). Physiologic parameters (heart rate, blood pressure, respiratory rate, and capnography), timed parameters (eg, time to initial effects and intubation), and quality of induction and intubation were recorded following drug administration. Venous blood was collected for analysis of plasma propofol concentrations using liquid chromatography-tandem mass spectrometry at various time points after propofol administration.
RESULTS
All animals were approachable following IM drug administration, and orotracheal intubation was achieved at 9.8 ± 2.0 minutes (mean ±SD) following propofol administration. The mean clearance for propofol was 14.2 ± 7.7 ml/min/kg, the mean terminal half-life was 82.4 ± 74.4 minutes, and the maximum concentration occurred at 2.8 ± 2.9 minutes. Two of 5 rhinoceros experienced apnea after propofol administration. Initial hypertension, which improved without intervention, was observed.
CLINICAL RELEVANCE
This study provides pharmacokinetic data and insight into the effects of propofol in rhinoceros anesthetized using etorphine, butorphanol, medetomidine, and azaperone. While apnea was observed in 2 rhinoceros, propofol administration allowed for rapid control of the airway and facilitated oxygen administration and ventilatory support.
Abstract
OBJECTIVE
To describe an outbreak of vesicular stomatitis virus (VSV) in southern white rhinoceros (SWR; Ceratotherium simum simum) and greater one-horned rhinoceros (GOHR; Rhinoceros unicornis) at a safari park in San Diego, CA, from May to September 2023.
ANIMALS
21 SWR and 5 GOHR in professionally managed care.
METHODS
Rhinoceros of both species presented with a range of clinical signs and severities. Lesion locations were categorized as cutaneous (coronary bands, heels and soles, limbs, ventrum, neck folds, and ears) and mucocutaneous (lips, nostrils, mucous membranes of the oral cavity, and vulva). Clinical signs included lethargy, lameness, difficulty with prehension, hyporexia to anorexia, and hypersalivation. Severely affected rhinoceros had clinical pathology findings consistent with systemic inflammation.
RESULTS
Vesicular stomatitis New Jersey virus was confirmed via PCR from swabs of lesions in 10/26 (38%) rhinoceros. Of these 10 confirmed cases, 9 (90%) were SWR and 1 (10%) was a GOHR. A further 6/26 (24%) were considered probable cases, and 10/26 (38%) were considered suspect cases based on clinical signs, but the inability to appropriately sample due to the housing environment precluded confirmation. Histopathology samples from 3 rhinoceros were consistent with VSV, and viral RNA was localized in histologic lesions via RNA in situ hybridization for 1 case. All rhinoceros survived infection despite severe systemic illness in 2 animals.
CLINICAL RELEVANCE
This case series describes the clinical appearance and progression of VSV in 2 rhinoceros species. To the authors' knowledge, this is the first report of VSV in a rhinoceros.
Abstract
Objective—To test the hypothesis that butorphanol or morphine induces antinociception with minimal respiratory depression in conscious red-eared slider turtles.
Design—Prospective crossover study.
Animals—37 adult male and female red-eared slider turtles (Trachemys scripta).
Procedures—Antinociception (n = 27 turtles) and respiratory (10 turtles) experiments were performed. Infrared heat stimuli were applied to the plantar surface of turtle limbs. Thermal withdrawal latencies were measured before and at intervals after SC administration of physiologic saline (0.9% NaCl) solution, butorphanol tartrate (2.8 or 28 mg/kg [1.27 or 12.7 mg/lb]), or morphine sulfate (1.5 or 6.5 mg/kg [0.68 or 2.95 mg/lb]). Ventilation was assessed in freely swimming turtles before and after SC administration of saline solution, butorphanol (28 mg/kg), or morphine (1.5 mg/kg).
Results—For as long as 24 hours after injection of saline solution or either dose of butorphanol, thermal withdrawal latencies among turtles did not differ. Low- and high-dose morphine injections increased latencies significantly by 8 hours. Ventilation was not altered by saline solution administration, was temporarily depressed by 56% to 60% for 1 to 2 hours by butorphanol (28 mg/kg) administration, and was significantly depressed by a maximum of 83 ± 9% at 3 hours after morphine (1.5 mg/kg) injection. Butorphanol and morphine depressed ventilation by decreasing breathing frequency.
Conclusions and Clinical Relevance—Although widely used in reptile species, butorphanol may not provide adequate antinociception for invasive procedures and caused short-term respiratory depression in red-eared slider turtles. In contrast, morphine apparently provided antinociception but caused long-lasting respiratory depression.
Abstract
Objective—To test the hypothesis that administration of butorphanol or morphine induces antinociception in bearded dragons and corn snakes.
Design—Prospective crossover study.
Animals—12 juvenile and adult bearded dragons and 13 corn snakes.
Procedures—Infrared heat stimuli were applied to the plantar surface of bearded dragon hind limbs or the ventral surface of corn snake tails. Thermal withdrawal latencies (TWDLs) were measured before (baseline) and after SC administration of physiologic saline (0.9% NaCl) solution (equivalent volume to opioid volumes), butorphanol tartrate (2 or 20 mg/kg [0.91 or 9.1 mg/lb]), or morphine sulfate (1, 5, 10, 20, or 40 mg/kg [0.45, 2.27, 4.5, 9.1, or 18.2 mg/lb]).
Results—For bearded dragons, butorphanol (2 or 20 mg/kg) did not alter hind limb TWDLs at 2 to 24 hours after administration. However, at 8 hours after administration, morphine (10 and 20 mg/kg) significantly increased hind limb TWDLs from baseline values (mean ± SEM maximum increase, 2.7 ± 0.4 seconds and 2.8 ± 0.9 seconds, respectively). For corn snakes, butorphanol (20 mg/kg) significantly increased tail TWDLs at 8 hours after administration (maximum increase from baseline value, 3.0 ± 0.8 seconds); the low dose had no effect. Morphine injections did not increase tail TWDLs at 2 to 24 hours after administration.
Conclusions and Clinical Relevance—Compared with doses used in most mammalian species, high doses of morphine (but not butorphanol) induced analgesia in bearded dragons, whereas high doses of butorphanol (but not morphine) induced analgesia in corn snakes.