Comparison of intramuscular alfaxalone with medetomidine-ketamine for inducing anaesthesia in Trachemys scripta spp. undergoing sterilization.

OBJECTIVE: To compare the effect of two anaesthetic protocols on heart rate (HR), time to muscle relaxation and tracheal intubation and time to surgical plane of anaesthesia, in Trachemys scripta spp. undergoing oophorectomy. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: A total of 43 healthy female turtles. METHODS: Morphine (1.5 mg kg-1) was injected subcutaneously 2 hours before anaesthesia induction. The turtles were randomly administered either medetomidine (0.2 mg kg-1) and ketamine (10 mg kg-1) (group MK; n = 23) or alfaxalone (20 mg kg-1) (group A; n = 20) intramuscularly followed by bupivacaine (2 mg kg-1) administered subcutaneously along the incision site. Anaesthesia was maintained with isoflurane delivered in oxygen (100%). HR and the anaesthetic depth score (ADS) were recorded every 5 minutes from induction to recovery. A Friedman test followed by Wilcoxon tests with Bonferroni adjustment were used to compare these non-parametric data (HR and ADS) between groups and over time. Time to muscle relaxation of neck and limbs (TMR), tracheal tube insertion (TTTI) and stage of surgical anaesthesia (TADS≤3) were recorded and compared between groups using a Welch's t test after logarithmic transformation. RESULTS: Median values of TMR, TTTI and TADS≤3 were 4, 9.5 and 25 minutes in group A, respectively, and 14, 20 and 35 minutes in group MK (TMR, TTTIp ≤ 0.0001; TADS≤3p = 0.001). Plane of anaesthesia was significantly deeper in group A than in group MK for the first 20 minutes (p < 0.01). HR at 10 and 15 minutes post injection was significantly lower in group MK (28 beats minute-1) than in group A (36 and 34 beats minute-1) (p < 0.02). CONCLUSIONS AND CLINICAL RELEVANCE: After intramuscular injection in Trachemys scripta spp., tracheal intubation, muscle relaxation and a surgical plane of anaesthesia developed faster with alfaxalone than medetomidine-ketamine.

Pharmacokinetics of levamisole in the red-eared slider turtles (Trachemys scripta elegans).

The pharmacokinetics and bioavailability of levamisole were determined in red-eared slider turtles after single intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration. Nine turtles received levamisole (10 mg/kg) by each route in a three-way crossover design with a washout period of 30 days. Blood samples were collected at time 0 (pretreatment), and at 0.25, 0.5, 1, 1.5, 3, 6, 9, 12, 18, 24, 36, and 48 hr after drug administration. Plasma levamisole concentrations were determined by a high-performance liquid chromatography assay. Data were analyzed by noncompartmental methods. The mean elimination half-life was 5.00, 7.88, and 9.43 hr for IV, IM, and SC routes, respectively. The total clearance and volume of distribution at steady state for the IV route were 0.14 L hr-1  kg-1 and 0.81 L/kg, respectively. For the IM and SC routes, the peak plasma concentration was 9.63 and 10.51 µg/ml, respectively, with 0.5 hr of Tmax . The bioavailability was 93.03 and 115.25% for the IM and SC routes, respectively. The IM and SC route of levamisole, which showed the high bioavailability and long t1/2ʎz , can be recommended as an effective way for treating nematodes in turtles.

Pharmacokinetics of tolfenamic acid in red-eared slider turtles (Trachemys scripta elegans).

OBJECTIVE: To determine the pharmacokinetics of tolfenamic acid (TA) after different routes of administration [intravenous (IV) and intramuscular (IM), 2 mg kg-1] and doses (IV, 2 and 4 mg kg-1) in red-eared slider turtles (Trachemys scripta elegans). STUDY DESIGN: Randomized experimental trial. ANIMALS: Sixteen healthy red-eared slider turtles. METHODS: Turtles were randomly assigned to two groups (n = 8 each). Group 1 received TA at a dose of 2 mg kg-1 IV and then IM, after a washout period of 30 days. Group 2 received 4 mg kg-1 TA IV. A noncompartmental analysis was used to calculate pharmacokinetic variables. RESULTS: No local and/or systemic adverse drug effects were observed in any turtle. Elimination half-life and mean residence time following IM administration at 2 mg kg-1 were significantly longer than those following IV administration. The bioavailability following IM administration was complete. The area under the plasma concentration-time curve, elimination half-life, mean residence time and total clearance were significantly different between the dose groups. CONCLUSIONS AND CLINICAL RELEVANCE: The absence of adverse reactions in the turtles of the study of TA along with the favourable pharmacokinetic properties (the long half-life and the complete bioavailability) of TA administered at the single doses of 2 and 4 mg kg-1 suggest the possibility of its effective use in turtles. However, further studies are required to establish a multiple dosage regimen of TA and to evaluate the clinical efficacy of administering TA.

Quantum Mechanics/Molecular mechanics calculations predict A1, not A2, is present in melanopsin (Opn4m) of red-eared slider turtles (Trachemys scripta elegans).

Melanopsin is a photopigment that plays a role in non-visual, light-driven, cellular processes such as modulation of circadian rhythms, retinal vascular development, and the pupillary light reflex (PLR). In this study, computational methods were used to understand which chromophore is harbored by melanopsin in red-eared slider turtles (Trachemys scripta elegans). In mammals, the vitamin A derivative 11-cis-retinal (A1) is the chromophore, which provides functionality for melanopsin. However, in red-eared slider turtles, a member of the reptilian class, the identity of the chromophore remains unclear. Red-eared slider turtles, similar to other freshwater vertebrates, possess visual pigments that harbor a different vitamin A derivative, 11-cis-3,4-didehydroretinal (A2), making their pigments more sensitive to red-light than blue-light, therefore, suggesting the chromophore to be the A2 derivative instead of the A1. To help resolve the chromophore identity, in this work, computational homology models of melanopsin in red-eared slider turtles were first constructed. Next, quantum mechanics/molecular mechanics (QM/MM) calculations were carried out to compare how A1 and A2 derivatives bind to melanopsin. Time dependent density functional theory (TDDFT) calculations were then used to determine the excitation energy of the pigments. Lastly, calculated excitation energies were compared to experimental spectral sensitivity data from responses by the irises of red-eared sliders. Contrary to what was expected, our results suggest that melanopsin in red-eared slider turtles is more likely to harbor the A1 chromophore than the A2. Furthermore, a glutamine (Q622.56) and tyrosine (Y853.28) residue in the chromophore binding pocket are shown to play a role in the spectral tuning of the chromophore.

Pharmacokinetics of intravenous and intramuscular danofloxacin in red-eared slider turtles (Trachemys scripta elegans).

This study aimed to investigate the pharmacokinetics of danofloxacin in red-eared slider turtle (Trachemys scripta elegans) following a single intravenous (IV) and intramuscular (IM) administrations of 6 mg/kg, using a two-way crossover study with 30-day washout period. Eight clinically healthy red-eared slider turtle weighing 410-600 g (mean 490 g) were used for the study. Danofloxacin concentrations were measured using the reversed-phase high-performance liquid chromatography. The plasma concentration-time data were evaluated by a non-compartmental method. After IV administration, the elimination half-life (t1/2ʎz), mean residence time (MRT0-∞), area under the concentration-time curve (AUC0-∞), volume of distribution at steady state and total body clearance in plasma were 24.17 hr, 30.64 hr, 143.31 hr·µg/ml, 1.29 l/kg and 0.04 l/hr/kg, respectively. Following IM administration, t1/2ʎz, MRT0-∞, AUC0-∞, peak concentration (Cmax), time to reach Cmax, and bioavailability in plasma were 32.00 hr, 41.15 hr, 198.23 hr·µg/ml, 8.75 µg/ml, 1.5 hr and 139.89%, respectively. Danofloxacin has clinically superior pharmacokinetic properties, including the complete IM absorption, slow elimination and wide volume of distribution in red-eared slider turtles. However, further pharmacokinetics/pharmacodynamics studies are necessary for the treatment of diseases caused by susceptible bacteria with known minimum inhibitory concentration values in red-eared slider turtles.