Aneurysm Associated with Vascular Wall Degeneration in Bearded Dragons (Pogona vitticeps)

This study describes the clinical, gross, and histologic findings in 17 cases of aneurysms in bearded dragons (Pogona vitticeps). The clinical presentation ranged from incidental to sudden and unexpected death. The affected vasculature was predominantly arterial; however, based on the topographical locations of the lesions, gross structure, and drainage, some veins were likely involved. Magnetic resonance imaging and computerized tomography scans of 1 animal showed a large aneurysm of the internal carotid artery extending from near its aortic origin into the caudal head. Aneurysms were organized in 5 groups based on their anatomical locations: cephalic, cranial coelom (for all near the heart), caudal coelom (for the mesenteric vessels and descending aorta), limbs, and tail. The cranial coelomic region was the most prevalent location. Gross findings were large hematomas or red serosanguineous fluid filling the adjacent area, as most of the aneurysms (94%) were ruptured at the time of the study. The main histological findings were degenerative changes of the vessel walls characterized by moderate to severe disruption of the collagen and elastic fibers of the tunica media and adventitia (100%), followed by thickening of the intima with thrombi formation (54%) and dissecting hematoma of the vessel wall (47%). Vasculitis (29%), mineralization (6%), and lipid deposits (6%) in the vessel wall were observed occasionally. Based on these findings, the vascular dilations and ruptures observed in bearded dragons likely are associated with weakness of the vessel walls caused by degenerative changes in the intimal and medial tunics.

Circadian control of sleep-related neuronal activity in lizards

Although diurnal animals displaying monophasic sleep patterns exhibit periodic cycles of alternating slow-wave sleep (SWS) and rapid eye movement sleep (REMS), the regulatory mechanisms underlying these regular sleep cycles remain unclear. Here, we report that in the Australian dragon Pogona vitticeps exposed to constant darkness (DD), sleep behavior and sleep-related neuronal activity emerged over a 24-h cycle. However, the regularity of the REMS/SWS alternation was disrupted under these conditions. Notably, when the lizards were then exposed to 12 h of light after DD, the regularity of the sleep stages was restored. These results suggest that sleep-related neuronal activity in lizards is regulated by circadian rhythms and that the regularity of REMS and SWS cycling is influenced by daytime light exposure.

Clinical presentation and disease prevalence of captive central bearded dragons (Pogona vitticeps) at veterinary clinics in Australia

Central bearded dragons (Pogona vitticeps) are one of the most popular reptile pets in Australia and around the world. Diseases, including metabolic bone disease, periodontal disease, and gastrointestinal endoparasites commonly affect captive animals. To determine the common reasons these lizards were presented to the veterinarian and to establish the prevalence of disease seen in captive P. vitticeps in Australia, this retrospective study evaluated the clinical records of three exotic pet veterinary hospitals. Records from 724 P. vitticeps were analysed, with 70 reasons for presentation and 88 diseases identified across 1000 visits to the veterinarian. Lethargy was the most reported reason for presentation (n = 181). The gastrointestinal tract (18.25%) and skin (18.25%) were the equally most commonly affected organ systems, followed by the musculoskeletal system (15.17%). Endoparasites were the most common single disease process (n = 103), followed by metabolic bone disease (n = 65), skin wounds (n = 59) and periodontal disease (n = 48). Of the patients that presented for routine preventive health examinations (n = 159), 45.30% received some form of intervention to treat or prevent disease. Many of the conditions that were identified by the veterinarians in this study are traditionally correlated with suboptimal husbandry and may be easily prevented. This study identified the common reasons for presentation to the veterinarian and the prevalence of disease in captive P. vitticeps in Australia, providing the first extensive retrospective analysis of objective reference literature for central bearded dragon owners and aspiring reptile veterinarians.

Establishment of a Real-Time PCR Assay for the Detection of Devriesea agamarum in Lizards

(1) Background: Devriesea (D.) agamarum is a potential cause of dermatitis and cheilitis in lizards. The aim of this study was to establish a real-time PCR assay for the detection of D. agamarum. (2) Methods: Primers and probe were selected targeting the 16S rRNA gene, using sequences of 16S rRNA genes of D. agamarum as well as of other bacterial species derived from GenBank. The PCR assay was tested with 14 positive controls of different D. agamarum cultures as well as with 34 negative controls of various non-D. agamarum bacterial cultures. Additionally, samples of 38 lizards, mostly Uromastyx spp. and Pogona spp., submitted to a commercial veterinary laboratory were tested for the presence of D. agamarum using the established protocol. (3) Results: Concentrations of as low as 2 × 10⁴ colonies per mL were detectable using dilutions of bacterial cell culture (corresponding to approximately 200 CFU per PCR). The assay resulted in an intraassay percent of coefficient of variation (CV) of 1.31% and an interassay CV of 1.80%. (4) Conclusions: The presented assay is able to detect D. agamarum in clinical samples, decreasing laboratory turn-around time in comparison to conventional culture-based detection methods.

Clinical course and pathologic study of retrobulbar histiocytic sarcoma in a central bearded dragon (Pogona vitticeps)

A central bearded dragon (Pogona vitticeps) presented with periorbital swelling and exophthalmos. A retrobulbar mass was detected, and enucleation with the mass was performed. Histologically, the mass was composed of a dense sheet and interlacing bundles of round to polygonal to short spindle-shaped cells with occasional bizarre mononuclear and multinucleated giant cells. Immunohistochemically, the neoplastic cells had various degrees of membranous and/or cytoplasmic granular reactivity to anti-ionized calcium-binding adapter molecule 1 and anti-CD204 antibodies. Ultrastructurally, the neoplastic cells had irregular nuclei and abundant cytoplasm with membrane-bound electron-dense lysosomes and endoplasmic reticula. These findings were consistent with a histiocytic sarcoma. The present study provided a detailed description of retrobulbar histiocytic sarcoma for the first time in a central bearded dragon.

Establishment of reference intervals for plasma protein electrophoresis and comparison of biochemical and protein electrophoresis evaluation of albumin in central bearded dragons (Pogona vitticeps)

The aim of this study is to develop a reference interval for plasma protein electrophoresis for wild free-roaming central bearded dragons (Pogona vitticeps). This will assist the veterinarian in diagnosing and monitoring diseases in wild and captive animals. The study group consisted of 29 wild central bearded dragons of which 22 were males and 7 were females. The plasma samples were obtained from animals in a previous study and were stored frozen at -20°C for 2-3 years before analysis. Plasma protein electrophoresis was performed on 100 uL of plasma. The data were evaluated for the difference between reproductively active females and pooled males with non-reproductively active females as well as the difference between biochemical and protein electrophoresis albumin. Biochemical albumin was found to be significantly higher than electrophoresis albumin in all animals, with a mild proportional bias present. Plasma protein electrophoresis identified albumin, α - 1 and 2, β - 1 and 2 and γ fractions. The reproductively active females in this study exhibited results that were distinct from pooled males and non-reproductively active females. This study provides a reference interval for plasma protein electrophoresis in central bearded dragons that can be used as a tool for health and disease monitoring and diagnosis. The importance of the use of method and sex/season appropriate reference intervals in reptile medicine is confirmed in this study.

Pax5 and CD3 immunophenotyping of lymphoma in 2 central bearded dragons

Two central bearded dragons (Pogona vitticeps), a 3-y-old male and a 5-y-old female, were diagnosed with different manifestations of lymphoma at the Kansas State Veterinary Diagnostic Laboratory between 2019 and 2020. The 3-y-old male was presented for postmortem evaluation and was in poor body condition. Microscopically, nearly all examined organs contained variable numbers of neoplastic round cells. Neoplastic cells in the stomach and liver had moderate immunoreactivity to CD3 consistent with multicentric T-cell lymphoma, and non-neoplastic lymphocytes infiltrating the stomach mass had strong immunoreactivity to Pax5. The 5-y-old female had an ulcerated oral mass located in the right lingual gingiva submitted as an excisional biopsy. Microscopically, the mass was composed of large numbers of neoplastic round cells in the epithelium and connective tissue that were strongly and diffusely positive for CD3 and frequently positive for Pax5, consistent with a dual-positive, localized, epitheliotropic T-cell lymphoma. Neoplastic and non-neoplastic lymphocytes did not stain with CD20 or CD79a. Neoplasms are increasingly reported as a cause of morbidity and mortality in reptiles. Our 2 cases illustrate various presentations of T-cell lymphoma and the effectiveness of CD3 and Pax5 immunohistochemistry in bearded dragons.

Klebsiella sp.-related infectious spondylitis in a bearded dragon (Pogona vitticeps)

Background

Spondylitis is an inflammation of the vertebrae that leads to a destructive process with exuberant new bone formation. Osteomyelitis can produce a distortion of the bone architecture, degenerative joint changes and ankyloses of adjacent vertebrae. In reptiles, intervertebral discs are absent, so the term discospondylitis is not used. In lizards, vertebral lesions have not been well studied. The present paper describes the first case of Klebsiella sp.-related spondylitis in a pet lizard (Pogona vitticeps).

Case presentation

A 2-year-old, female bearded dragon (Pogona vitticeps) was presented for clinical examination due to a decreased activity level, decreased appetite and constipation. Blood tests showed no remarkable alterations. The haemogram showed normal parameters with relative lymphocytosis, although the absolute number of lymphocytes did not differ from the reference values. A computed tomography scan revealed a mixed osteolytic-proliferative bone lesion diffusing to the first and last tracts of the pre-sacral vertebrae together. A small amount of material obtained from the spinal swelling was sampled with an aseptic technique for bacterial culture, which was positive for Klebsiella sp. The antibiogram revealed sensitivity to enrofloxacin, marbofloxacin, and chloramphenicol and intermediate sensitivity to gentamicin. Complete return to spontaneous feeding was achieved 15 days after the beginning of antibiotic and anti-inflammatory therapy.

Conclusions

In veterinary medicine, spondylitis represents a well-known disease in small companion animals. In mammals, the most common aetiologic agents are fungi and bacteria. Antibiotic therapy was set based on the antibiogram, and marbofloxacin was chosen at a dosage of 10 mg/kg subcutaneously (SC) once per day (SID). After only 7 days of antibiotic therapy, the clinical condition improved significantly; the patient started feeding and drinking spontaneously and gained weight. This case should remind clinicians of the importance of always performing antibiograms before choosing any antibiotic therapy. Considering reptiles, there have been few papers about spinal diseases, mostly regarding snakes and a few about Iguana iguana. Relative to other species of saurians, the literature remains lacking.

Pathology of the Bearded Dragon (Pogona vitticeps): a Retrospective Analysis of 36 Cases

The bearded dragon (Pogona vitticeps) is a common species in the pet reptile trade and in zoological collections. Despite this, only a few reviews detailing common causes of mortality have been published. The goal of this retrospective study was to compile information related to the presence and prevalence of various diseases in bearded dragons in several private and one zoological collection. Findings from 36 animals, necropsied over a 20-year period were categorized on the basis of the cause of death or euthanasia and the organ system affected. Multiple contributors to death were identified in a subset of animals (n = 12; 33.33%) and were counted in more than one category. The most common contributors to death by category were inflammatory (infectious or non-infectious) diseases (n = 25; 69.44%), followed by chronic/degenerative diseases (n = 17; 47.22%). Diseases or conditions that were systemic, or affected the hepatobiliary system, were the most commonly implicated in death. The most frequent histological findings included hepatic fatty change, renal tubular epithelial pigmentation and the presence of faveolar hyaline-like material. Although Chi square testing did not reveal an association between these common findings and comorbidities, a statistically significant association was found between chronic/degenerative causes of death and renal tubular epithelial pigment. Chi square testing of categorical variables, including contributors to death, primary organ(s) affected, sex, age class and institution, identified statistically significant associations between males and chronic/degenerative disease (P = 0.043) and inflammatory contributors to death and private collection animals (P = 0.039). Death due to inflammatory contributors was significantly higher in the 1-5-year-old and >5-year-old age classes (P = 0.02).

Haematology and plasma biochemistry reference intervals in wild bearded dragons (Pogona vitticeps)

The aim of the study is to provide haematology and plasma biochemistry reference intervals for wild free-roaming central bearded dragons (Pogona vitticeps). These data will aid the veterinarian in determining the health and husbandry status of the pet bearded dragon. The study group consisted of 130 wild central bearded dragons. The data were assigned into two groups: Breeding Season (BS) from September to November and Non-Breeding Season (NBS) from December to March. These groups were further divided into sex and reproduction status with females determined to either be gravid or non-gravid. The 83 male and 47 female dragons were captured in north western New South Wales, Australia, centred around the towns of Bourke, Wanaaring and Tibooburra. Haematological and plasma biochemistry parameters were measured using standard methods. Data were analysed for the effects of sex, season and gravid status. There were significant differences between sexes in PCV, basophils, albumin, globulin, amylase, calcium, phosphate and triglycerides. There were seasonal differences in PCV, basophils, uric acid, glucose, globulin, calcium, phosphate, cholesterol and triglycerides. There were significant differences in phosphate and cholesterol between gravid and non-gravid dragons within the breeding season. There were variations in haematology and biochemistry parameters depending on sex, season and reproductive status of females. These reference intervals differed from previous studies of captive central bearded dragons and can provide some insight into captive conditions compared to wild animals.

Pathogenesis of Isospora amphiboluri in Bearded Dragons (Pogona vitticeps)

Isospora amphiboluri is a common coccidian found in captive bearded dragons (Pogona vitticeps). To minimize the impact of this parasite, it is important to characterize its pathogenesis so that we can develop appropriate methods for diagnosis and treatment. Forty-five juvenile bearded dragons were used for this two-part study. In the first part, ten bearded dragons were infected with 20,000 oocysts per os, while a control group of five animals received only water. Feces were collected over 45 days and screened for oocysts. In the second part, thirty bearded dragons were used to characterize the pathogenesis of I. amphiboluri. Twenty-five bearded dragons were infected as described previously, while five animals served as controls. Five infected bearded dragons and one control were humanely euthanized on days 4, 8, 12, 16, and 20 post-infection for complete necropsies. The pre-patent period for I. amphiboluri was found to be 18.6 ± 1.9 days (range 15-22 days). Histopathology confirmed that I. amphiboluri follows a homoxenous life cycle. Infections begin in the duodenum and progress to the colon over time. The findings of this study can be used to develop better quarantine and treatment protocols for captive bearded dragons.

How to Handle Your Dragon: Does Handling Duration Affect the Behaviour of Bearded Dragons (Pogona Vitticeps)?

Simple Summary

Keeping reptiles as pets has become relatively common; therefore, it is important for us to understand more about how different aspects of their life as pets might affect their welfare. Very little is known about the effects of handling on reptiles, particularly the type of gentle handling (i.e., without restraint) likely to be experienced by pet animals. Therefore, this study investigated whether the amount of time that bearded dragons, a commonly kept lizard species, experienced gentle handling impacted on their behaviour in tests that give insight into how they may be feeling. We found that longer durations of handling appeared to increase stress-related behaviour slightly. This finding suggests that handling bearded dragons for longer periods of time, even in a gentle way, may be mildly stressful for them. However, we do not know whether animals would become accustomed to handling for longer periods with more experience.

Abstract

Reptiles are popular as pets and it is, therefore, important to understand how different aspects of housing and husbandry impact on their behaviour and welfare. One potential cause of stress in captive reptiles is interaction with humans; in particular, the effect of handling. However, little research on handling has been carried out with reptiles, particularly relating to the type of gentle handling likely to be experienced by pet animals. The aim of this study was therefore to determine whether the amount of time that bearded dragons (Pogona vitticeps), a commonly kept pet species, experienced gentle handling induced no or differing levels of anxiety, as reflected in their subsequent behavioural response to novelty. We found that there appeared to be a mildly aversive effect of handling time on subsequent behavioural response to novelty. Longer durations of handling (5 min or 15 min) appeared to increase anxiety-related behaviour, with handled animals showing more frequent tongue flicking behaviour when they experienced a novel environment and reduced time spent in close proximity to a novel object. These results suggest that handling bearded dragons, even in a gentle way, may increase their anxiety. However, it is not yet known whether animals may habituate to handling for longer periods if provided with additional experience.

avium in an inland-bearded dragon (Pogona vitticeps) - A case report and review of the literature

Here, we report the first case of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps) from a wildlife sanctuary in Victoria, Australia. Molecular characterisation was conducted by PCR-coupled sequencing of regions in the small subunit of nuclear RNA (SSU), actin and large subunit of nuclear RNA (LSU) genes. The sequences obtained grouped with those of C. ornithophilus and other C. avium genotypes/variants originating from reptiles or birds. We discuss this case in relation to the current state of knowledge of C. avium of birds and reptiles, considering provenance and environment (agricultural, pet industry, wildlife, zoo or wildlife park) as well as clinical context, and pathological changes associated with cryptosporidiosis in these host animals.

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Characterisation of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps).

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Molecular differentiation of C. cf. avium from other members of the C. avium clade.

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Pathogenicity of C. cf. avium seems higher than other members of this clade.

IRIDIUM 192 (192-Ir) HIGH DOSE RATE BRACHYTHERAPY IN A CENTRAL BEARDED DRAGON (POGONA VITTICEPS) WITH ROSTRAL SQUAMOUS CELL CARCINOMA

A 0.5-kg, 9-yr-old, male central bearded dragon (Pogona vitticeps) presented with a proliferative mass (0.4 × 0.2 inches) on the left rostral aspect of the lower lip. Physical examination, blood work, and whole-body radiography did not reveal any other abnormalities. Histopathology confirmed squamous cell carcinoma. Considering the small size of the tumor, absence of deep tissue infiltration, and its radioresponsive characteristics, iridium 192 high dose rate brachytherapy was attempted. The dragon initially received three doses of 4 Gy/site at days 0, 7, and 17. Recurrence developed 3 mo later. Three more fractions of 6 Gy/site at days 0, 7, and 14 were delivered according to the same procedure. A second recurrence appeared after 2 mo. Surgical excision was then performed, followed by four fractions of 6 Gy/site on the surgical site at 2-wk intervals. Sixteen months posttreatment, no recurrence of the mass was observed.

Anaplastic Sarcoma and Sertoli Cell Tumor in a Central Bearded Dragon (Pogona vitticeps)

A five-year-old male central bearded dragon (Pogona vitticeps) was presented for investigation of blood in the voided urates. A small cutaneous mass was detected in the gular region, but clinical examination was otherwise unremarkable. Fecal parasitology was negative. Initially, further diagnostics were declined, and antimicrobial treatment was initiated. At re-examination one month later, the gular mass had increased in size and an additional mass was detected within the celomic cavity. Both masses were surgically excised and diagnosed by histopathology as a high-grade anaplastic sarcoma (gular mass), resembling a histiocytic sarcoma, and a Sertoli cell tumor (coelomic mass). Neither of these have been previously reported in the central bearded dragon. Twenty months post-surgery, the lizard remains well with no recurrence of clinical signs or evidence of tumor re-growth.

Ophthalmic examination, biometry, and histologic findings in captive inland bearded dragons (Pogona vitticeps)

OBJECTIVE

To report ophthalmic examination, biometry, phenol red thread test (PRTT), intraocular pressure (IOP), and histologic findings from a private collection of inland bearded dragons (Pogona vitticeps).

ANIMALS STUDIED

Fourteen inland bearded dragons.

PROCEDURES

Complete ophthalmic examinations were performed on all animals, including slit-lamp biomicroscopy, indirect ophthalmoscopy, fluorescein stain, phenol red thread test, and rebound tonometry. B-mode ultrasonography was used to measure anterior chamber depth, axial lens thickness, vitreal chamber depth, and axial globe length. Horizontal corneal diameter was estimated using ImageJ software. Histologic assessment was obtained for one of the bearded dragons that died following the study period.

RESULTS

The median PRTT value was 7.27 mm/15 seconds. Mean IOP was 6.29 ± 1.60 mm Hg and 2.14 ± 1.37 mm Hg using the dog and undefined calibration settings, respectively. Median axial globe length was 11.75 mm. Mean anterior chamber depth and mean lens thickness were 2.06 ± 0.35 mm and 3.38 ± 0.45 mm, respectively. Median vitreal chamber depth was 6.79 mm. Mean horizontal corneal diameter was 5.138 ± 0.346 mm. Two distinct ocular phenotypes were observed, with two of the bearded dragons having corneal globosa, deep anterior chambers, and tufts of iridal vessels and fibrillar material extending into the anterior chamber.

CONCLUSIONS

The ultrasound biometry, PRTT, and rebound tonometry results may serve as a guideline for ophthalmic parameters in healthy bearded dragons. Examination and testing of greater numbers of animals are necessary to establish true reference ranges and determine if the observed ocular phenotypes represent normal variants or pathologic changes.

Reproductive phenotype predicts adult bite-force performance in sex-reversed dragons (Pogona vitticeps)

Sex-related differences in morphology and behavior are well documented, but the relative contributions of genes and environment to these traits are less well understood. Species that undergo sex reversal, such as the central bearded dragon (Pogona vitticeps), offer an opportunity to better understand sexually dimorphic traits because sexual phenotypes can exist on different chromosomal backgrounds. Reproductively female dragons with a discordant sex chromosome complement (sex reversed), at least as juveniles, exhibit traits in common with males (e.g., longer tails and greater boldness). However, the impact of sex reversal on sexually dimorphic traits in adult dragons is unknown. Here, we investigate the effect of sex reversal on bite-force performance, which may be important in resource acquisition (e.g., mates and/or food). We measured body size, head size, and bite force of the three sexual phenotypes in a colony of captive animals. Among adults, we found that males (ZZm) bite more forcefully than either chromosomally concordant females (ZWf) or sex-reversed females (ZZf), and this difference is associated with having relatively larger head dimensions. Therefore, adult sex-reversed females, despite apparently exhibiting male traits as juveniles, do not develop the larger head and enhanced bite force of adult male bearded dragons. This pattern is further illustrated in the full sample by a lack of positive allometry of bite force in sex-reversed females that is observed in males. The results reveal a close association between reproductive phenotype and bite force performance, regardless of sex chromosome complement.

Detection and Characterization of Invertebrate Iridoviruses Found in Reptiles and Prey Insects in Europe over the Past Two Decades

Invertebrate iridoviruses (IIVs), while mostly described in a wide range of invertebrate hosts, have also been repeatedly detected in diagnostic samples from poikilothermic vertebrates including reptiles and amphibians. Since iridoviruses from invertebrate and vertebrate hosts differ strongly from one another based not only on host range but also on molecular characteristics, a series of molecular studies and bioassays were performed to characterize and compare IIVs from various hosts and evaluate their ability to infect a vertebrate host. Eight IIV isolates from reptilian and orthopteran hosts collected over a period of six years were partially sequenced. Comparison of eight genome portions (total over 14 kbp) showed that these were all very similar to one another and to an earlier described cricket IIV isolate, thus they were given the collective name lizard-cricket IV (Liz-CrIV). One isolate from a chameleon was also subjected to Illumina sequencing and almost the entire genomic sequence was obtained. Comparison of this longer genome sequence showed several differences to the most closely related IIV, Invertebrateiridovirus6 (IIV6), the type species of the genus Iridovirus, including several deletions and possible recombination sites, as well as insertions of genes of non-iridoviral origin. Three isolates from vertebrate and invertebrate hosts were also used for comparative studies on pathogenicity in crickets (Gryllusbimaculatus) at 20 and 30 °C. Finally, the chameleon isolate used for the genome sequencing studies was also used in a transmission study with bearded dragons. The transmission studies showed large variability in virus replication and pathogenicity of the three tested viruses in crickets at the two temperatures. In the infection study with bearded dragons, lizards inoculated with a Liz-CrIV did not become ill, but the virus was detected in numerous tissues by qPCR and was also isolated in cell culture from several tissues. Highest viral loads were measured in the gastro-intestinal organs and in the skin. These studies demonstrate that Liz-CrIV circulates in the pet trade in Europe. This virus is capable of infecting both invertebrates and poikilothermic vertebrates, although its involvement in disease in the latter has not been proven.

HYPERTENSIVE HEART DISEASE AND ENCEPHALOPATHY IN A CENTRAL BEARDED DRAGON (POGONA VITTICEPS) WITH SEVERE ATHEROSCLEROSIS AND FIRST-DEGREE ATRIOVENTRICULAR BLOCK

A 0.5 kg, 5-yr-old male bearded dragon (Pogona vitticeps) presented with a 2-mo history of lethargy, anorexia, and impaired locomotion. Upon physical examination, bradyarrhythmia (heart rate: 20 beats/min) and balance disorders were noted. Electrocardiography revealed a first-degree atrioventricular block (P-R interval: 360 ms). On echocardiography, all cardiac chambers were slightly above normal ranges. Complete blood count, blood biochemistry, and T4 were unremarkable except for mildly elevated aspartate aminotransferase. Adenovirus testing was negative by polymerase chain reaction. Following euthanasia, necropsy revealed marked thickening of the arterial trunks and histopathology confirmed multifocal atherosclerosis of efferent heart vessels, arteriosclerosis of cerebral arterioles, and multifocal spongiosis of brain tissue, more pronounced in the optic chiasma. Owing to its severity, atherosclerosis may have contributed to chronic arterial hypertension with damages to the heart, brain vessels, and brain tissue-optic chiasma.

Waking the sleeping dragon: gene expression profiling reveals adaptive strategies of the hibernating reptile Pogona vitticeps

Background

Hibernation is a physiological state exploited by many animals exposed to prolonged adverse environmental conditions associated with winter. Large changes in metabolism and cellular function occur, with many stress response pathways modulated to tolerate physiological challenges that might otherwise be lethal. Many studies have sought to elucidate the molecular mechanisms of mammalian hibernation, but detailed analyses are lacking in reptiles. Here we examine gene expression in the Australian central bearded dragon (Pogona vitticeps) using mRNA-seq and label-free quantitative mass spectrometry in matched brain, heart and skeletal muscle samples from animals at late hibernation, 2 days post-arousal and 2 months post-arousal.

Results

We identified differentially expressed genes in all tissues between hibernation and post-arousal time points; with 4264 differentially expressed genes in brain, 5340 differentially expressed genes in heart, and 5587 differentially expressed genes in skeletal muscle. Furthermore, we identified 2482 differentially expressed genes across all tissues. Proteomic analysis identified 743 proteins (58 differentially expressed) in brain, 535 (57 differentially expressed) in heart, and 337 (36 differentially expressed) in skeletal muscle. Tissue-specific analyses revealed enrichment of protective mechanisms in all tissues, including neuroprotective pathways in brain, cardiac hypertrophic processes in heart, and atrophy protective pathways in skeletal muscle. In all tissues stress response pathways were induced during hibernation, as well as evidence for gene expression regulation at transcription, translation and post-translation.

Conclusions

These results reveal critical stress response pathways and protective mechanisms that allow for maintenance of both tissue-specific function, and survival during hibernation in the central bearded dragon. Furthermore, we provide evidence for multiple levels of gene expression regulation during hibernation, particularly enrichment of miRNA-mediated translational repression machinery; a process that would allow for rapid and energy efficient reactivation of translation from mature mRNA molecules at arousal. This study is the first molecular investigation of its kind in a hibernating reptile, and identifies strategies not yet observed in other hibernators to cope stress associated with this remarkable state of metabolic depression.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5750-x) contains supplementary material, which is available to authorized users.

Immunohistochemical staining patterns of alpha-keratins in normal tissues from two reptile species: implications for characterization of squamous cell carcinomas

Background

Cytokeratins with epitopes in common with those of alpha (acidic and basic) mammalian keratins have been immunohistochemically demonstrated in the epidermis of reptiles. However, there are no reports of immunohistochemical staining patterns of alpha-keratins in other tissues from reptiles. Because the epithelial tumours usually retain the keratin patterns of their normal epithelial origin, it is necessary to know in advance these patterns in the major normal epithelia and organs. We used anti-alpha human keratin AE1 and AE3 monoclonal antibodies to study the staining patterns of alpha-keratins in the major normal epithelia and organs from two reptile species [the bearded dragon (Pogona vitticeps) and the loggerhead sea turtle (Caretta caretta)]. We also studied the immunolocalization of alpha-keratins in squamous cell carcinomas (SCCs) in a bearded dragon and two loggerhead turtles.

Results

Acidic alpha-keratin (AE1 positive) was detected in many of the epithelial tissues of the bearded dragons; however, the detection of basic alpha-keratin (AE3 positive) was much more limited. Alpha-keratins were detected in a greater number of tissues of loggerhead turtles compared with those observed in bearded dragons. In the bearded dragon SCC, all layers of the nests of neoplastic cells, including the cornified layer of the keratin pearls, were strongly reactive with the AE1 antibody. However, a weak reactivity using the AE3 antibody was detected in the basal and intermediate layers of these nests. In the cutaneous SCCs of both sea turtles, acidic alpha-keratin was detected in the basal and suprabasal layers, and in all of the invasive neoplastic cords, while basic alpha-keratin was mainly detected in the invasive neoplastic cords. The pattern observed in the metastases in both turtles consisted of immunohistological detection of acidic alpha-keratin in all metastatic foci, and limited or lack of detection of basic alpha-keratin.

Conclusions

This study provides, for the first time, information about the immunohistochemical staining patterns of alpha-keratins in normal tissues from bearded dragons and loggerhead sea turtles, and confirms the usefulness of AE1 and AE3 monoclonal antibodies in these reptile species. The use of these antibodies also contributed to a better characterization of SCCs in these species.

Skull Development, Ossification Pattern, and Adult Shape in the Emerging Lizard Model Organism Pogona vitticeps: A Comparative Analysis With Other Squamates

The rise of the Evo-Devo field and the development of multidisciplinary research tools at various levels of biological organization have led to a growing interest in researching for new non-model organisms. Squamates (lizards and snakes) are particularly important for understanding fundamental questions about the evolution of vertebrates because of their high diversity and evolutionary innovations and adaptations that portrait a striking body plan change that reached its extreme in snakes. Yet, little is known about the intricate connection between phenotype and genotype in squamates, partly due to limited developmental knowledge and incomplete characterization of embryonic development. Surprisingly, squamate models have received limited attention in comparative developmental studies, and only a few species examined so far can be considered as representative and appropriate model organism for mechanistic Evo-Devo studies. Fortunately, the agamid lizard Pogona vitticeps (central bearded dragon) is one of the most popular, domesticated reptile species with both a well-established history in captivity and key advantages for research, thus forming an ideal laboratory model system and justifying his recent use in reptile biology research. We first report here the complete post-oviposition embryonic development for P. vitticeps based on standardized staging systems and external morphological characters previously defined for squamates. Whereas the overall morphological development follows the general trends observed in other squamates, our comparisons indicate major differences in the developmental sequence of several tissues, including early craniofacial characters. Detailed analysis of both embryonic skull development and adult skull shape, using a comparative approach integrating CT-scans and gene expression studies in P. vitticeps as well as comparative embryology and 3D geometric morphometrics in a large dataset of lizards and snakes, highlights the extreme adult skull shape of P. vitticeps and further indicates that heterochrony has played a key role in the early development and ossification of squamate skull bones. Such detailed studies of embryonic character development, craniofacial patterning, and bone formation are essential for the establishment of well-selected squamate species as Evo-Devo model organisms. We expect that P. vitticeps will continue to emerge as a new attractive model organism for understanding developmental and molecular processes underlying tissue formation, morphology, and evolution.

First report of fatal disseminated microsporidiosis in two inland bearded dragons Pogona vitticeps in Japan

Introduction.Encephalitozoon pogonae is a newly described pathogen belonging to the phylum Microsporidia. In Austria and the USA, this species has been isolated from fatal and disseminated cases of captive-bred inland bearded dragons. Here, we report the case of fatal disseminated microsporidiosis caused by E. pogonae in two bearded dragons in Japan. Case Presentation. The two lizards from different private households in Tokyo, Japan, had been brought to an animal hospital for examination. In both cases, the animal presented with a history of weight loss for several weeks. There were no improvements in clinical symptoms and the lizards deteriorated and finally died. Histopathological examination demonstrated necrotizing granulomatous inflammation attributed to disseminated microsporidian infection. Nucleotide sequencing of the nuclear ribosomal internal transcribed spacer region identified the microsporidian as E. pogonae with sequence identity of 100 %. Conclusion. We report the first case, to our knowledge, of disseminated microsporidiosis caused by E. pogonae in inland bearded dragons in Japan. Although it is difficult to diagnose prenatally since the signs are nonspecific, the disease should be considered in the differential diagnosis of chronic infections that do not respond to antibiotics.

Identification of interleukin genes in Pogona vitticeps using a de novo transcriptome assembly from RNA-seq data

Interleukins are a group of cytokines with complex immunomodulatory functions that are important for regulating immunity in vertebrate species. Reptiles and mammals last shared a common ancestor more than 350 million years ago, so it is not surprising that low sequence identity has prevented divergent interleukin genes from being identified in the central bearded dragon lizard, Pogona vitticeps, in its genome assembly. To determine the complete nucleotide sequences of key interleukin genes, we constructed full-length transcripts, using the Trinity platform, from short paired-end read RNA sequences from stimulated spleen cells. De novo transcript reconstruction and analysis allowed us to identify interleukin genes that are missing from the published P. vitticeps assembly. Identification of key cytokines in P. vitticeps will provide insight into the essential molecular mechanisms and evolution of interleukin gene families and allow for characterization of the immune response in a lizard for comparison with mammals.

High-coverage sequencing and annotated assembly of the genome of the Australian dragon lizard Pogona vitticeps

Background

The lizards of the family Agamidae are one of the most prominent elements of the Australian reptile fauna. Here, we present a genomic resource built on the basis of a wild-caught male ZZ central bearded dragon Pogona vitticeps.

Findings

The genomic sequence for P. vitticeps, generated on the Illumina HiSeq 2000 platform, comprised 317 Gbp (179X raw read depth) from 13 insert libraries ranging from 250 bp to 40 kbp. After filtering for low-quality and duplicated reads, 146 Gbp of data (83X) was available for assembly. Exceptionally high levels of heterozygosity (0.85 % of single nucleotide polymorphisms plus sequence insertions or deletions) complicated assembly; nevertheless, 96.4 % of reads mapped back to the assembled scaffolds, indicating that the assembly included most of the sequenced genome. Length of the assembly was 1.8 Gbp in 545,310 scaffolds (69,852 longer than 300 bp), the longest being 14.68 Mbp. N50 was 2.29 Mbp. Genes were annotated on the basis of de novo prediction, similarity to the green anole Anolis carolinensis, Gallus gallus and Homo sapiens proteins, and P. vitticeps transcriptome sequence assemblies, to yield 19,406 protein-coding genes in the assembly, 63 % of which had intact open reading frames. Our assembly captured 99 % (246 of 248) of core CEGMA genes, with 93 % (231) being complete.

Conclusions

The quality of the P. vitticeps assembly is comparable or superior to that of other published squamate genomes, and the annotated P. vitticeps genome can be accessed through a genome browser available at https://genomics.canberra.edu.au.

Electronic supplementary material

The online version of this article (doi:10.1186/s13742-015-0085-2) contains supplementary material, which is available to authorized users.