Great ape cardiovascular disease: aetiopathogenesis, risk factors and diagnostic tools

Chimpanzees, orangutans, gorillas and bonobos are commonly kept in zoos across the world, and the understanding of their physiology and susceptibility to diseases is critical for the maintenance of healthy captive individuals and the protection of wild populations. Cardiovascular disease (CVD) is known as a major cause of morbidity and mortality in zoo great apes, and the Ape Heart Project has been studying its epidemiology and pathogenesis since 2014. The first chapter of this thesis critically examines the literature available related to great ape CVD and questions the possible aetiologies of this disease process. The three subsequent chapters explore possible diagnostic tools that could help with the investigation of specific risk factors of CVD in great apes, with zoo chimpanzees as models. Oscillometric and invasive blood pressure measurement devices are compared highlighting the inaccuracy of non-invasive devices when measuring blood pressure in anaesthetised chimpanzees. The value of implantable loop recorders (ILR) is also assessed to investigate the occurrence of arrhythmic events in chimpanzees considered at risk of cardiac disease, and this study demonstrates that ILRs are a valid tool for cardiac screening in great apes. The use of dried blood spots (DBS) to measure vitamin D in chimpanzees is explored in Chapter 4 and found that the analytical error is greater in DBS compared with serum samples, thus limiting the use of the DBS technique to field studies when the collection and analysis of serum samples are not achievable. Chapter 5 investigates the vitamin D status of European zoo chimpanzees and found relatively low serum vitamin D concentrations in a large contingent of this population during the low UVB season, supporting the hypothesis that vitamin D insufficiency may be a risk factor for CVD disease in great apes. Chapter 6 describes the findings of the systematic post-mortem examination of 50 great ape hearts and illustrates some differences seen between species. Finally, the last chapter of this thesis depicts the application of microcomputed tomography to formalin-fixed chimpanzee hearts and the discovery of bone formation within the cardiac skeleton of chimpanzees affected by myocardial fibrosis. Further studies investigating risk factors of great ape cardiovascular disease, especially hypertension and hypovitaminosis D, are urgently needed

Assessing the Educational Value of a Zoo Placement for Veterinary Students: A Report on Student Feedback and Perceptions

Zoological medicine is an expanding field with limited practical training opportunities for veterinary students. Those training programs that do exist require significant financial and resource investment by both veterinary schools and the zoological organizations involved. This article summarizes the findings of a retrospective survey of students carried out to ascertain the educational value of a compulsory 5-day-long zoo clinical placement for final-year veterinary students. We aimed to explore the placement’s potential impact on students’ knowledge and attitudes toward zoological medicine and the role of modern zoos and conservation. Data were collected by means of an end-of-placement questionnaire (N = 200) and statistically analyzed for pre- versus post-placement changes and the effect of pre-placement interest and experience on student responses. Despite the placement’s short time frame and lack of opportunity for in-depth comprehensive training in zoological medicine, students reported that the placement had a positive educational impact. More than 90% of students stated that their understanding about modern zoos was good or excellent at the end of the placement (compared with 35.0% before the placement), and 43.0% reported that the placement had a positive impact on their attitudes toward zoos. Students self-reported an increased understanding of the work of zoo clinicians, and there was a highly significant positive change in the students’ reported opinions regarding wildlife conservation in general. We provide preliminary evidence to suggest that even short-duration but immersive zoo-based practical training has positive educational value for veterinary students

Discovery Of A Bone In Chimpanzee Hearts

The os cordis (heart bone) is a rare bone found only in a few animals in the world. We discovered an os cordis in some chimpanzees. The os cordis was found in males and females, and in young and old animals. It was not present in chimps with healthy hearts, only in those with severe heart disease. We also discovered that a tissue called cartilage was present around the bone. The presence of cartilage gives us clues about how and why these rare bones develop

Great ape cardiovascular disease: aetiopathogenesis, risk factors and diagnostic tools

Chimpanzees, orangutans, gorillas and bonobos are commonly kept in zoos across the world, and the understanding of their physiology and susceptibility to diseases is critical for the maintenance of healthy captive individuals and the protection of wild populations. Cardiovascular disease (CVD) is known as a major cause of morbidity and mortality in zoo great apes, and the Ape Heart Project has been studying its epidemiology and pathogenesis since 2014. The first chapter of this thesis critically examines the literature available related to great ape CVD and questions the possible aetiologies of this disease process. The three subsequent chapters explore possible diagnostic tools that could help with the investigation of specific risk factors of CVD in great apes, with zoo chimpanzees as models. Oscillometric and invasive blood pressure measurement devices are compared highlighting the inaccuracy of non-invasive devices when measuring blood pressure in anaesthetised chimpanzees. The value of implantable loop recorders (ILR) is also assessed to investigate the occurrence of arrhythmic events in chimpanzees considered at risk of cardiac disease, and this study demonstrates that ILRs are a valid tool for cardiac screening in great apes. The use of dried blood spots (DBS) to measure vitamin D in chimpanzees is explored in Chapter 4 and found that the analytical error is greater in DBS compared with serum samples, thus limiting the use of the DBS technique to field studies when the collection and analysis of serum samples are not achievable. Chapter 5 investigates the vitamin D status of European zoo chimpanzees and found relatively low serum vitamin D concentrations in a large contingent of this population during the low UVB season, supporting the hypothesis that vitamin D insufficiency may be a risk factor for CVD disease in great apes. Chapter 6 describes the findings of the systematic post-mortem examination of 50 great ape hearts and illustrates some differences seen between species. Finally, the last chapter of this thesis depicts the application of microcomputed tomography to formalin-fixed chimpanzee hearts and the discovery of bone formation within the cardiac skeleton of chimpanzees affected by myocardial fibrosis. Further studies investigating risk factors of great ape cardiovascular disease, especially hypertension and hypovitaminosis D, are urgently needed

Cardiac structure and function characterized across age groups and between sexes in healthy wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries

Objective: To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries. Animals: 290 wild-born captive chimpanzees. Procedures: Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests. Results: Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts. Conclusions and Clinical Relevance: Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anaesthetic agents on cardiac structure and function in chimpanzees

Sourcing high tissue quality brains from deceased wild primates with known socio‐ecology

The selection pressures that drove dramatic encephalisation processes through the mammal lineage remain elusive, as does knowledge of brain structure reorganisation through this process. In particular, considerable structural brain changes are present across the primate lineage, culminating in the complex human brain that allows for unique behaviours such as language and sophisticated tool use. To understand this evolution, a diverse sample set of humans' closest relatives with varying socio-ecologies is needed. However, current brain banks predominantly curate brains from primates that died in zoological gardens. We try to address this gap by establishing a field pipeline mitigating the challenges associated with brain extractions of wild primates in their natural habitat. The success of our approach is demonstrated by our ability to acquire a novel brain sample of deceased primates with highly variable socio-ecological exposure and a particular focus on wild chimpanzees. Methods in acquiring brain tissue from wild settings are comprehensively explained, highlighting the feasibility of conducting brain extraction procedures under strict biosafety measures by trained veterinarians in field sites. Brains are assessed at a fine-structural level via high-resolution MRI and state-of-the-art histology. Analyses confirm that excellent tissue quality of primate brains sourced in the field can be achieved with a comparable tissue quality of brains acquired from zoo-living primates. Our field methods are noninvasive, here defined as not harming living animals, and may be applied to other mammal systems than primates. In sum, the field protocol and methodological pipeline validated here pose a major advance for assessing the influence of socio-ecology on medium to large mammal brains, at both macro- and microstructural levels as well as aiding with the functional annotation of brain regions and neuronal pathways via specific behaviour assessments