The chelonian respiratory system

Surveillance of Mycoplasma agassizii in Texas tortoises (Gopherus berlandieri) for translocation with emphasis on treatment and recovery

Background

Texas tortoises (Gopherus berlandieri) are a Texas-state threatened species. Translocation is often suggested as a mitigation option; however, disease status and the potential for spread must be considered prior to such efforts. Mycoplasma infection of the upper respiratory tract is a concern within tortoise populations, which requires monitoring so translocation efforts do not inadvertently spread the disease.

Objectives

We determined and compared the prevalences of Mycoplasma agassizii in Texas tortoises from donor and recipient sites in southern Texas prior to translocation, treated Mycoplasma agassizii-infected tortoises with danofloxacin, and developed alternate Mycoplasma agassizii treatments for Texas tortoises.

Methods

We collected 171 and 23 Texas tortoises from a 270-ha and a 100-ha donor site and recipient site, respectively. We began a regimen of danofloxacin (6 mg/kg body weight injected subcutaneously every other day for 30 days) for tortoises with clinical signs (N = 20). We noted an additional 10 tortoises began displaying clinical signs of upper respiratory tract disease (URTD) after translocation, so we designed a trial to test tulathromycin (5 mg/kg body weight given intramuscularly once/week for 7 weeks) or oxytetracycline (8 mg/kg body weight given subcutaneously once/day for 14 days) as Mycoplasma treatments for symptomatic tortoises.

Results

Within the donor and recipient sites, 56 (32.7%) and 8 (34.8%), respectively, had antibody titers suggestive of past exposure. Eighteen tortoises from the donor site (10.5%) and 2 from the recipient site (8.7%) displayed clinical signs (i.e., clear serous nasal discharge, conjunctivitis, and palpebral edema) consistent with Mycoplasmal URTD upon initial collection, even though all polymerase chain reaction (PCR) results were negative for active shedding of Mycoplasma agassizii. We ceased treatment after the first dose of danofloxacin due to adverse reactions, which only began to subside after 72 h from the initial dose. Neither tulathromycin or oxytetracycline caused the clinical signs of URTD to subside after a 50-day treatment period.

Conclusion

Mycoplasma is a persistent issue facing Texas tortoises. Stressors, such as translocation, can cause Mycoplasma-seropositive tortoises to display clinical symptoms of URTD, which can abate without treatment, once the stressor subsides.

Implications

Danofloxacin, the recommended treatment for Mycoplasma infection in tortoises, is too potent for Texas tortoises.

Pharmacokinetic characteristics of florfenicol in green sea turtles (Chelonia mydas) and hawksbill sea turtles (Eretmochelys imbricata) after intramuscular administration

The pharmacokinetics of florfenicol (FFC) in green sea and hawksbill sea turtles were evaluated following intramuscular (i.m.) administration at two different dosages of 20 or 30 mg/kg body weight (b.w.). This study (longitudinal design) used 5 green sea and 5 hawksbill sea turtles for the two dosages. Blood samples were collected at assigned times up to 168 h. FFC plasma samples were analyzed using validated high-performance liquid chromatography equipped with diode array detection. The pharmacokinetic analysis was performed using a non-compartment approach. The FFC plasma concentrations increased with the dosage. The elimination half-life was similar between the treatment groups (range 19-25 h), as well as the plasma protein binding (range 18.59%-20.65%). According to the surrogate PK/PD parameter (T > MIC, 2 μg/mL), the 20 and 30 mg/kg dosing rates should be effective doses for susceptible bacterial infections in green sea and hawksbill sea turtles.

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.

Differences in the anatomy of the lower respiratory tract in selected species of the order Testudines

The lower airways of turtles consist of the larynx, trachea and bronchi. Due to incomplete information about the anatomical structure of the lower respiratory tract in turtles, we decided to explore this topic more deeply. The material for this study included 95 turtle cadavers. Terrestrial tortoises were represented by 63 individuals from 8 species, aquatic and semi-aquatic turtles by 32 individuals from 11 species. The sex ratio was 54 females to 41 males. In addition to the anatomical autopsies and assessments of the macroscopic structures, numerous measurements were performed. The length, width and height of the larynx and trachea, and the length of the bronchi were measured. We found clinical significance in two parameters. The first one is the formation of the rima glottidis, which is significantly shorter and narrower in the aquatic turtles than in the terrestrial tortoises. It follows that for these species, we should use a smaller diameter of endotracheal cannula for intubation. The second parameter is a very short trachea in tortoises of the genus Testudo. The length of the trachea is only a few centimetres, which significantly increases the risk of intubation into one bronchus only.

Respiratory Disorders in Chelonians

"Respiratory tract disease in chelonians can be difficult to treat and as such proper diagnostics are paramount. Infectious agents that can affect the respiratory tract of chelonians include viral, bacterial, fungal, and parasitic organisms. Noninfectious diseases can also develop. Because chelonians lack a proper diaphragm, changes in size of celomic organs can cause compression of the respiratory system. These conditions result in clinical signs that could be attributed to the respiratory system, such as open-mouth breathing. In this article, anatomy, physiology, and current standards for diagnostics and treatments of major diseases of the respiratory tract in chelonians are discussed."