Evidence for seasonal shift in the reproduction of Aldabra giant tortoises (Aldabrachelys gigantea) in managed care in the Northern hemisphere compared to the natural habitat in the Southern hemisphere.

Ex situ breeding constitutes an important tool for species conservation; however, many reptile species are not managed sustainably under human care due to poor fecundity in ex situ settings. In this study, we tested whether the translocation of a seasonally reproducing species to a different environment results in decoupling of extrinsic signals and intrinsic conditions. The endocrinological patterns of plasma steroid sex hormones, follicular development, and mating behaviour of two female and two male sexually mature Aldabra tortoises (Aldabrachelys gigantea) in a zoological institution in the Northern hemisphere was aligned with enclosure climate data (mean monthly daylight duration, temperature, and precipitation) and compared with respective hormone patterns of wild individuals and climate conditions in the native habitat on the Aldabra Atoll in the Southern hemisphere. Whereas occurrence of mating behaviour was not considered a limiting factor, lack of ovulation and subsequent follicular atresia was the main reason for the lack of reproductive output. While it was impossible to elucidate the triggering factors of ovulation and the multifactorial complexity of reproduction was not fully addressed, this study indicates suboptimal temperature conditions and relative temporal shifts of interacting external triggers (temperature and photoperiod) in the zoo setting.

Morphological evidence for the physiological nature of follicular atresia in veiled chameleons (Chamaeleo calyptratus).

Follicular atresia (FA) has been assumed to serve different functions in reptiles, e.g. helping to develop hierarchies, limiting clutch size, and regression of ovarian structures. Reproductive output is dependent on a balance between ovulations and FA. Excessive rates of FA may not only be detrimental for the survival of a population, but have also been associated with pathological conditions. In order to gain insights into the physiological and potentially pathological processes of FA, we performed a decriptive study on the morphological features of the ovaries in sexually mature female veiled chameleons (Chamaeleo calyptratus, VC). Of 60 clinically healthy female VC with continuous ovarian cycling and at least one confirmed cycle with FA over at least 1.5 years, 30 were selected for macroscopic evaluation of ovarian appearance and 7 were subjected to histology and immunohistology. While FA of previtellogenic follicles happened at a low rate, expected for a species with two germinal beds per ovary and polyautochronic reproductive pattern, atresia in the late vitellogenic stage affected entire generations of follicles, consequential to ovulatory failure. Histologically, no pathological processes were identified in any of the animals. Rather, three stages of FA (early, middle, late) were defined and vitellogenic follicles showed two distinct morphological types of FA: yolky and cystic. Yolky FA was found in 21/30 (70%) animals, while cystic FA co-occurred in 9/30 (30%) of the animals.

Metastasizing squamous cell carcinoma in a 50-year-old Eastern Hermann's tortoise (Testudo hermannii boettgeri).

A 50-year-old female Hermann's tortoise (Testudo hermannii boettgeri) was presented with anorexia and lethargy. Clinical examination revealed multiple, visually inconspicuous but indentable areas in the shell corresponding to osteolysis radiographically. Soft tissue nodules and osteolytic lesions were also noted in the limbs. Laboratory results revealed elevated aspartate aminotransferase activity and uric acid concentrations, hypoglycemia, and hyperphosphatemia. Klebsiella oxytoca was isolated from a biopsied scutal area, and the biopsy suggested neoplasia. After a short period of clinical improvement, the animal's condition deteriorated, and it died. Post mortem computed tomography revealed polyostotic lytic lesions of multiple bones and the shell with associated soft tissue nodules protruding into the coelom, and nodular lung lesions. Necropsy, histopathology, and immunohistochemistry secured a diagnosis of a poorly differentiated, pan-cytokeratin-positive squamous cell carcinoma with widespread soft tissue and bone metastases, osteolysis and desmoplasia.

ULTRASONOGRAPHIC AND COMPUTED TOMOGRAPHIC CHARACTERISTICS OF THE REPRODUCTIVE CYCLE IN FEMALE VEILED CHAMELEONS (CHAMAELEO CALYPTRATUS).

Female veiled chameleons, Chamaeleo calyptratus, have a high fecundity and fast maturation, which makes them a suitable model species for squamate reproduction. The authors investigated the morphological follicular development of a group of 20 healthy adult animals over a 12-mon period using ultrasonography (US) and CT. Four stages of follicular development could be distinguished by imaging diagnostics and were confirmed by histology: previtellogenesis, vitellogenesis, gravidity, and atresia. Using a linear ultrasound transducer (18 MHz), previtellogenic follicles could be visualized as small, round, hypoechoic structures. Identification of this stage was unreliable on CT. On US, vitellogenic follicles remained round and showed increasing echogenicity from the hypoechoic center outwards, displaying vinyl-like hyperechoic banding in later stages. On CT, early vitellogenic follicles were round, hyperdense structures, which reduced in density as they grew. A hyperdense inner ring with a hypodense central point characterized late vitellogenesis. Following ovulation, eggs became distinctly oval on both CT and US, with formation of a hyperdense or hyperechoic outer ring, respectively. Atresia followed in cases where no ovulation occurred, and was divided into yolky and cystic atresia. Sonographically, early yolky atretic follicles became unevenly shaped, packed against one another, and developed heterogenous content. Late atretic follicles were homogenous and reduced in size. Reduction of density and uneven shape were also observed on CT. Cystic atretic follicles developed an anechoic cavity with a dense peripheral accumulation of content. In many animals 2-3 generations of atretic follicles were observed without indication of impairment to the development of the newest batch of follicles. Thus, follicular atresia need not necessarily lead to a pathological condition in veiled chameleons, at least not within a few consecutive cycles.

Treatment options, complications and long-term outcomes for limb fractures in pet rabbits.

BACKGROUND: Limb fractures represent the most common orthopaedic disease in pet rabbits. However, only a few studies have evaluated therapeutic details of limb fractures. There are no data available for long-term outcomes of limb fracture treatment. METHODS: The medical records of six institutions were reviewed retrospectively to identify cases of traumatic limb bone fractures in pet rabbits between 1999 and 2020. The medical records (n = 387) were analysed for details of fracture prevalence, aetiology, therapy protocols, treatment complications, outcome and long-term effects. In addition to the retrospective data evaluation, 13 rabbits were re-evaluated in person in recent clinical analyses, including orthopaedic examination, radiography and computed-tomographic imaging. Details of long-term effects of fracture treatment were requested over the telephone for a further 232 animals using a standardised questionnaire. RESULTS: Long bone fractures accounted for the majority of all fractures (296/387; 76.5%). Hindlimb fractures (301/387; 77.7%) were more common than forelimb fractures (86/387; 22.2%), and tibial fractures and combined fractures of the tibia and fibula (119/387; 30.8%) were observed most frequently. Most fracture treatments were based on osteosynthesis procedures (243/328; 74.1%). Treatment complications occurred in 130 out of 328 (39.6%) cases. A high bodyweight (p = 0.047) and an older age (p = 0.01) were found to be significant risk factors for the emergence of therapy complications. Overall, 75.4% of animals (175/232) had a satisfactory long-term outcome. Limb posture anomalies were evaluated in 61 cases (26.3%). LIMITATIONS: The multi-centre approach led to the inclusion of various institutions, veterinarians, treatment protocols and rabbit populations that might have influenced the results. The medical records were reviewed retrospectively, so there were some data that were lacking or could not be collected in a standardised manner. Furthermore, rabbit owners' evaluation of long-term outcomes might be prone to error, despite the use of a standardised interview questionnaire. CONCLUSION: Limb fractures are a common orthopaedic issue in pet rabbits. The patient's bodyweight and age are significant risk factors for the emergence of complications during the fracture treatment process. Long-term orthopaedic effects, such as abnormal limb posture and permanent lameness of the affected limb, were observed regularly.

RETROSPECTIVE STUDY OF CAUSES OF ANIMAL MORTALITY IN LJUBLJANA ZOO 2005-2015.

Zoos harbor large collections of diverse species, aiding in both conservation and education, as well as research in multiple scientific fields. However, the most common causes of death in zoo animals around the world remain unclear because few extensive reports or reviews are published on this topic. This information could greatly improve preventive veterinary medicine in zoologic gardens. This study provides a retrospective overview of the causes of death of animals from the Ljubljana Zoo in the years 2005-2015. During this period, a total of 353 animals were submitted for necropsy, of which 244 were mammals, 85 were birds, and 25 were reptiles. The causes of deaths were divided into infectious diseases (38%), dysfunctions of individual organs (20%), traumas (13%), parasitosis (7%), reproductive disorders (6%), metabolic disorders (3%), neoplastic disease (4%), and intoxications (4%). In some cases, the cause of death was unable to be determined (7%), most commonly because of autolysis of the body. The results of this retrospective study bring a general overview of the epizootiologic situation in the Ljubljana Zoo over an 11-yr period and valuable information to other zoos to optimize preventative plans and diagnostics.