Sterilisation of hybrid Galapagos tortoises (Geochelone nigra) for island restoration. Part 1: endoscopic oophorectomy of females under ketamine-medetomidine anaesthesia

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.

Sedation and Anesthesia of Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African Spurred Tortoises (Centrochelys sulcata): A Retrospective Review (2009-2019)

Simple Summary

Anesthesia is often required for the medical management of large tortoise species, but little has been published regarding effective anesthetic regimens for these species. The purpose of this study was to review anesthetic regimens that have been used safely and effectively in Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African spurred (Centrochelys sulcata) tortoises, with the aim of improving medical management.

Abstract

Tortoises belong to the taxonomic family Testudinidae, which is considered one of the most imperiled families of the order Testudines. Anesthesia is often required for the medical and surgical management of large tortoises. The objectives of this retrospective study were to review drug regimens used to successfully anesthetize Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea) and African spurred (Centrochelys sulcata) tortoises, and to compare the times to effect and to extubation in tortoises administered different premedication protocols. Anesthetic records of giant tortoises admitted to the University of Florida College of Veterinary Medicine between January 2009 and December 2019 were reviewed. A total of 34 tortoises (six Aldabra, 23 Galapagos, and five African spurred) were included, resulting in 64 anesthetic events. Frequently used premedication protocols included an α₂-adrenergic agonist and ketamine combined with either midazolam (group α₂−adrenergic agonist, midazolam, ketamine, AMK; n = 34), a μ-opioid receptor agonist (group α₂−adrenergic agonist, μ-opioid receptor agonist, ketamine, AOK; n = 13), or a μ−opioid receptor agonist and midazolam (group α₂−adrenergic agonist, midazolam, μ-opioid receptor agonist, ketamine, AMOK; n = 10). Inhalant anesthetics (isoflurane, n = 21; sevoflurane, n = 23) were frequently used for maintenance of anesthesia following premedication. Out of the 34 total tortoises, 22 had only one anesthetic event, five had two anesthetic events, three had three anesthetic events, and four had four or more anesthetic events. Few adverse effects were observed and there was no mortality reported during the peri-anesthetic period. Sedation and general anesthesia of giant tortoises can be successfully performed with a combination of an α₂-adrenergic agonist and ketamine in combination with midazolam and/or a μ−opioid receptor agonist.

Haematology and plasma biochemistry reference intervals for the critically endangered western Santa Cruz Galapagos tortoise (Chelonoidis porteri)

Reference intervals (RIs) are an increasingly valuable tool for monitoring captive and free-living wildlife populations. Galapagos tortoises are one of the most emblematic species on Earth with 9 of the 12 extant species considered endangered due to human activities. As part of a long-term health assessment within the Galapagos Tortoise Movement Ecology Programme, we sampled a total of 210 free-living Santa Cruz Galapagos tortoises (Chelonoidis porteri). We collected blood from the brachial vein and performed packed cell volume (PCV), total solids (TS), morphological evaluation, white blood cell (WBC) count estimates and differentials and a VetScan biochemistry panel for each individual. We calculated 95% RIs and 90% confidence intervals (CIs) using the Reference Value Advisor tool and following international standard guidelines. Tortoises were categorized by estimated age and sex, with RI and CI reported here for 164 adult tortoises and 46 sub-adult tortoises. We found significant differences between sexes, with adult females presenting a lower PCV and higher values for both calcium and potassium. Among age groups, adult tortoises presented higher PCV, TS and albumin and lower WBC counts, aspartate aminotransferase and creatine kinase than sub-adult tortoises. We also found that tortoises presented higher numbers of lymphocytes during the dry season, but higher basophils, eosinophils, phosphorus, potassium and TS during the humid season. The heterophil:lymphocyte ratio did not differ between groups. To the authors' knowledge, this is the first report of formal plasma biochemistry and haematology RI for free-living Galapagos tortoises. With the present study we provide an important diagnostic tool for captive-breeding programs in the Galapagos and zoological institutions globally that care for giant tortoises. The ultimate goal of this study is to contribute to the understanding of giant tortoise baseline health parameters and to inform local management decisions that help to conserve these emblematic species.

Coelioscopic-assisted prefemoral ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope

The purpose of this study was to assess the unilateral prefemoral coelioscopic-assisted approach for ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope. Twenty healthy turtles were randomly assigned to one of two groups, for right (GR; n=10) or left (GL; n=10) prefemoral access, for coelioscopic-assisted ovariosalpingectomy. Anesthesia and surgery times, body weight, and ovary/oviduct weight data were recorded. Anesthesia and surgery times did not differ significantly between the groups. Wound closure was the most time-consuming surgical step. Ovary and body weights significantly affected the exposure time of the ipsilateral and contralateral ovaries, respectively. Two intraoperative complications were reported. All the animals recovered uneventfully. The digital otoscope can be safely and effectively used for coelioscopic-assisted single-access, unilateral prefemoral ovariosalpingectomy in d`Orbigny slider.

Comparison of Lateral and Dorsal Recumbency during Endoscope-Assisted Oophorectomy in Mature Pond Sliders (Trachemys scripta)

Simple Summary

Ovariectomy via the prefemoral fossa, with or without endoscopic assistance, is a well-described technique for elective and therapeutic sterilization in chelonians. The choice between lateral and dorsal recumbency is generally left to the surgeon’s preference, with no data supporting an objective superiority of one over the other. In pond sliders, common pets but also an invasive alien species in Europe, we compared two different recumbencies (right lateral with a left fossa approach, and dorsal with a right fossa approach) regarding ease of access to the coelomic cavity, ease of identification of the ovary opposite to the surgical breach, first and second ovary removal times, and total surgical time. No significant difference was found between the two groups for any evaluated parameter. Endoscope-assisted prefemoral ovariectomy in mature pond sliders can be indifferently performed in lateral or dorsal recumbency, depending on the preference of the surgeon, on the animal’s pathophysiologic status, or on the necessity to perform concurrent procedures.

Abstract

Ovariectomy via the prefemoral fossa is a well-described technique for sterilization in chelonians. The choice between lateral and dorsal recumbency is generally left to the surgeon’s preference, with no data supporting an objective superiority of one over the other. Twenty-four sexually mature female pond sliders (Trachemys scripta) were enrolled for elective prefemoral endoscope-assisted oophorectomy, and were randomly divided in two groups: 12 animals were placed in right lateral recumbency with a left fossa approach (Group A), and 12 in dorsal recumbency with a right fossa approach (Group B). Scoring systems were applied to assess the ease of access to the coelomic cavity, and the ease of identification of the ovary opposite to the surgical incision. A negative correlation was found between the body weight of the animals and the ease of access to the coelom (p = 0.013), making the access easier in smaller animals. No significant difference was found between the two groups in terms of ease of access to the coelomic cavity, first ovary removal time, ease of identification of the second ovary, second ovary removal time, or total surgery time.

Locoregional Anesthesia in Exotic Pets

Locoregional techniques are used in exotic pets to improve perioperative analgesia as well as decrease the requirement of systemic analgesics during and after invasive surgeries. This article focuses on the techniques that have been described for exotic mammals, birds, and reptiles, focusing on those that rely on ultrasonographic or nerve stimulator guidance.

Endoscopic assisted orchiectomy in Herman’s tortoises (Testudo hermanni sp.)

Objective: Male tortoises in captivity are often aggressive against other males or females, in particular during mating season related to hormonal influences (testosterone). Castration in males is the treatment of choice in many vertebrate species. A novel technique of minimal invasive castration is presented for Herman’s tortoises (Testudo hermanni).

Material and methods: The procedure was performed in ten mature males. An endoscope (2.7 mm/30° angled) was inserted into a prefemoral incision on each side. The testicle was resected after ligation of the gubernaculum testis and the spermatic cord using hemoclips.

Results: Each testicle could be removed in approximately 20 minutes. Complications like hemorrhage or damage of adjacent tissue did not occur and all animals recovered uneventfully.

Conclusions and clinical relevance: Using the bilateral prefemoral entrance offers an alternative option for orchiectomy in Herman’s tortoises without dissection of the shell. Thus complications like hemorrhage or impaired wound healing followed by sequestration of the bone flap are prevented. Because of the anatomical settings and the risk of tissue damage and time consumption, a unilateral approach is not recommended. Fasting the animals is necessary due to the voluminous gastrointestinal tract of this herbivorous tortoise and emptying the urinary bladder provides more space for manipulations in the coelomic cavity and prevents clipping and cutting of adjacent organs. The magnification via the endoscope is beneficial for orientation in the coelomic cavity, which is formed by the extremely convex carapace. Without this equipment it is challenging to visualize the dorsocaudally located gonads through the relatively small incision and the inserted instruments might block the view at the surgical field. Administration of hemoclips achieved a good hemostasis and the testicles could be resected without major blood loss. The described technique is a gentle method for resection of the testicles in this species and can be adapted to other European tortoise species of equal size.

Biochemistry and hematology parameters of the San Cristóbal Galápagos tortoise (Chelonoidis chathamensis)

As part of a planned introduction of captive Galapagos tortoises (Chelonoidis chathamensis) to the San Cristóbal highland farms, our veterinary team performed thorough physical examinations and health assessments of 32 tortoises. Blood samples were collected for packed cell volume (PCV), total solids (TS), white blood cell count (WBC) differential, estimated WBC and a biochemistry panel including lactate. In some cases not all of the values were obtainable but most of the tortoises have full complements of results. Despite a small number of minor abnormalities this was a healthy group of mixed age and sex tortoises that had been maintained with appropriate husbandry. This work establishes part of a scientific and technical database to provide qualitative and quantitative information when establishing sustainable development strategies aimed at the conservation of Galapagos tortoises.

Single-incision, prefemoral bilateral oophorosalpingectomy without coelioscopy in an Indian star tortoise (Geochelone elegans) with follicular stasis

A female Indian star tortoise (Geochelone elegans) was evaluated for anorexia and suspected coelomic masses. Clinical examination indicated follicular stasis. The tortoise was anesthetized and placed in dorsal left lateral recumbency for a right prefemoral approach. The ovaries and oviducts were exposed through the right prefemoral incision. The ovarian vasculature, the mesovarium, the oviduct, mesosalpinx and associated vasculature were ligated and transected. Bilateral oophorosalpingectomy was performed through the incision, without coelioscopy. Since then, the same procedure has been performed in five other tortoises, and all recovered well. These results suggest that bilateral oophorosalpingectomy, performed through a prefemoral incision, without coelioscopy, is a safe and practical approach for treating follicular stasis in tortoises.

Reproductive Medicine in Freshwater Turtles and Land Tortoises

Chelonian reproductive medicine is an extremely important facet to ensuring captive populations for the pet trade and conservation efforts around the globe. This article covers basic chelonian reproductive anatomy and physiology, natural history, behavior, and sexing chelonians, in addition to discussing reproductive disorders that are commonly seen by veterinarians. Reproductive disorders covered include infertility, dystocia, follicular stasis, egg yolk coelomitis, phallus prolapse, and reproductive neoplasia. It is hoped that this information will allow clinicians to recognize, understand, and successfully treat reproductive disorders in chelonians, thus providing the best available care for our chelonian patients.

Reptile Soft Tissue Surgery

The surgical approach to reptiles can be challenging. Reptiles have unique physiologic, anatomic, and pathologic differences. This may result in frustrating surgical experiences. However, recent investigations provided novel, less invasive, surgical techniques. The purpose of this review was to describe the technical aspects behind soft tissue surgical techniques that have been used in reptiles, so as to provide a general guideline for veterinarians working with reptiles.

Coelioscopic and Endoscope-Assisted Sterilization of Chelonians

Elective sterilization is a safe and well-established surgical procedure performed in dogs and cats worldwide. Conversely, chelonian sterilization has been mostly performed therapeutically, because of the intricate anatomy and difficult access to the reproductive organs, and consequently, reproductive problems and diseases remain common. With the advance of veterinary endoscopy, novel techniques of soft tissue prefemoral coelioscopic and endoscope-assisted sterilization have been published, and preventative chelonian sterilization is now a reality. Nevertheless, extrapolations between species should be carefully considered, and further studies are warranted. This article summarizes and describes the current coelioscopic and coelioscope-assisted sterilization techniques for chelonia.

Clinical Applications of Cystoscopy in Chelonians

The medical approach to chelonians can be challenging. Cystoscopy may be useful to evaluate morphologic changes in the viscera without the need of celiotomy, and is a valuable diagnostic tool. The size and transparency of the urinary bladder in chelonians allows visualization of most coelomic organs. Through cystoscopy the external aspect of stomach, intestine, heart, lungs, liver, pancreas, spleen, kidneys, testes, and ovaries may be visualized. Although a definitive diagnosis cannot be achieved, rapid identification of the diseased system through cystoscopy may be possible. Furthermore, cystoscopy is fundamental for diagnosis and treatment of lower urogenital disorders.

Equivalency of Galápagos giant tortoises used as ecological replacement species to restore ecosystem functions

Loss of key plant-animal interactions (e.g., disturbance, seed dispersal, and herbivory) due to extinctions of large herbivores has diminished ecosystem functioning nearly worldwide. Mitigating for the ecological consequences of large herbivore losses through the use of ecological replacements to fill extinct species' niches and thereby replicate missing ecological functions has been proposed. It is unknown how different morphologically and ecologically a replacement can be from the extinct species and still provide similar functions. We studied niche equivalency between 2 phenotypes of Galápagos giant tortoises (domed and saddlebacked) that were translocated to Pinta Island in the Galápagos Archipelago as ecological replacements for the extinct saddlebacked giant tortoise (Chelonoidis abingdonii). Thirty-nine adult, nonreproductive tortoises were introduced to Pinta Island in May 2010, and we observed tortoise resource use in relation to phenotype during the first year following release. Domed tortoises settled in higher, moister elevations than saddlebacked tortoises, which favored lower elevation arid zones. The areas where the tortoises settled are consistent with the ecological conditions each phenotype occupies in its native range. Saddlebacked tortoises selected areas with high densities of the arboreal prickly pear cactus (Opuntia galapageia) and mostly foraged on the cactus, which likely relied on the extinct saddlebacked Pinta tortoise for seed dispersal. In contrast, domed tortoises did not select areas with cactus and therefore would not provide the same seed-dispersal functions for the cactus as the introduced or the original, now extinct, saddlebacked tortoises. Interchangeability of extant megaherbivores as replacements for extinct forms therefore should be scrutinized given the lack of equivalency we observed in closely related forms of giant tortoises. Our results also demonstrate the value of trial introductions of sterilized individuals to test niche equivalency among candidate analog species.

Coelioscopic orchiectomy can be effectively and safely accomplished in chelonians

Coelioscopic orchiectomy was performed in 27 male turtles (25 juvenile to adult red-eared sliders (Trachemys scripta elegans), one adult eastern painted turtle (Chrysems picta picta), and one juvenile male yellow-spotted Amazon River turtle (Podocnemis unifilis)). Orchiectomy was conducted under coelioscopic visualisation using ligation and transection of the mesorchium, or transection of the mesorchium with monopolar radiosurgical scissors. In 22 cases, bilateral orchiectomy was performed through a single incision; five turtles required bilateral incisions. All turtles recovered from anaesthesia. Nine turtles died within one year of surgery from conditions believed to be unrelated to surgery. One turtle was lost to follow-up. Seventeen turtles remain clinically healthy one to three years postoperatively. Coelioscopic orchiectomy provides a minimally invasive method for sterilisation of male chelonians and provides excellent visualisation during surgery. This technique is a useful model for the development of additional minimally invasive surgical techniques for chelonians.

Effects of native and non-native vertebrate mutualists on plants

Extinctions can leave species without mutualist partners and thus potentially reduce their fitness. In cases where non-native species function as mutualists, mutualism disruption associated with species' extinction may be mitigated. To assess the effectiveness of mutualist species with different origins, we conducted a meta-analysis in which we compared the effectiveness of pollination and seed-dispersal functions of native and non-native vertebrates. We used data from 40 studies in which a total of 34 non-native vertebrate mutualists in 20 geographic locations were examined. For each plant species, opportunistic non-native vertebrate pollinators were generally less effective mutualists than native pollinators. When native mutualists had been extirpated, however, plant seed set and seedling performance appeared elevated in the presence of non-native mutualists, although non-native mutualists had a negative overall effect on seed germination. These results suggest native mutualists may not be easily replaced. In some systems researchers propose taxon substitution or the deliberate introduction of non-native vertebrate mutualists to reestablish mutualist functions such as pollination and seed dispersal and to rescue native species from extinction. Our results also suggest that in places where all native mutualists are extinct, careful taxon substitution may benefit native plants at some life stages.