Browsing by Author "Miller, Michele"
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- ItemBovine tuberculosis in African buffalo (Syncerus caffer): Progression of pathology during infection(PLOS, 2022-11-11) Lakin, Hilary Ann; Tavalire, Hannah; Sakamoto, Kaori; Buss, Peter; Miller, Michele; Budischak, Sarah A.; Raum, Kristina; Ezenwa, Vanessa O.; Beechler, Brianna; Jolles, AnnaBackground Bovine tuberculosis (BTB) is a zoonotic disease of global importance endemic in African buffalo (Syncerus caffer) in sub-Saharan Africa. Zoonotic tuberculosis is a disease of global importance, accounting for over 12,000 deaths annually. Cattle affected with BTB have been proposed as a model for the study of human tuberculosis, more closely resembling the localization and progression of lesions in controlled studies than murine models. If disease in African buffalo progresses similarly to experimentally infected cattle, they may serve as a model, both for human tuberculosis and cattle BTB, in a natural environment. Methodology/Principal findings We utilized a herd of African buffalo that were captured, fitted with radio collars, and tested for BTB twice annually during a 4-year-cohort study. At the end of the project, BTB positive buffalo were culled, and necropsies performed. Here we describe the pathologic progression of BTB over time in African buffalo, utilizing gross and histological methods. We found that BTB in buffalo follows a pattern of infection like that seen in experimental studies of cattle. BTB localizes to the lymph nodes of the respiratory tract first, beginning with the retropharyngeal and tracheobronchial lymph nodes, gradually increasing in lymph nodes affected over time. At 36 months, rate of spread to additional lymph nodes sharply increases. The lung lesions follow a similar pattern, progressing slowly, then accelerating their progression at 36 months post infection. Lastly, a genetic marker that correlated to risk of M. bovis infection in previous studies was marginally associated with BTB progression. Buffalo with at least one risk allele at this locus tended to progress faster, with more lung necrosis. Conclusions/Significance The progression of disease in the African buffalo mirrors the progression found in experimental cattle models, offering insight into BTB and the interaction with its host in the context of naturally varying environments, host, and pathogen populations.
- ItemEtorphine-Ketamine Constant Rate Infusion for Maintenance of Anaesthesia in a Compromised White Rhinoceros (Ceratotherium simum)(Hindawi, 2019-03-12) Pohlin, Friederike; Buss, Peter; Miller, Michele; Steenkamp, Gerhard; Gleed, Robin; Poore, Luke; Boesch, Jordyn; Zeiler, GarethA subadult white rhinoceros bull presented for oesophageal endoscopic evaluation and foreign body removal under general anaesthesia. The animal had a history of nasal and oral regurgitation of water and ingesta with weight-loss for 6 days prior to the procedure and had been diagnosed with oesophageal obstruction caused by a bailing wire. Anaesthesia was induced with intramuscular etorphine and azaperone delivered remotely by dart, followed by an intravenous bolus of ketamine. The trachea was intubated, and anaesthesia was maintained with an etorphine-ketamine constant rate infusion (CRI). The rhinoceros did not respond predictably to induction of anaesthesia and developed life-threatening systemic hypotension throughout the 90-minute procedure. A mega-vertebrate demand ventilator was successfully used to provide intermittent positive pressure ventilation when the rhinoceros developed apnoea. This case report describes the maintenance of anaesthesia of a white rhinoceros using an etorphine-ketamine CRI and the causes and management of hypotension and respiratory impairment observed in this patient.
- ItemGut microbiome differences between wild and captive black rhinoceros – implications for rhino health(Nature Research (part of Springer Nature), 2019) Gibson, Keylie M.; Nguyen, Bryan N.; Neumann, Laura M.; Miller, Michele; Buss, Peter; Daniels, Savel; Ahn, Michelle J.; Crandall, Keith A.; Pukazhenthi, BudhanA number of recent studies have shown the importance of the mammalian gut microbiome in host health. In the context of endangered species, a few studies have examined the relationship between the gut microbiome in wild versus captive populations due to digestive and other health issues. Unfortunately, the results seem to vary across taxa in terms of captive animals having higher, lower, or equivalent microbiome diversity relative to their wild counterparts. Here, we focus on the black rhinoceros as captive animals suffer from a number of potentially dietary related health effects. We compared gut microbiomes of wild and captive black rhinos to test for differences in taxonomic diversity (alpha and beta) and in functional diversity of the microbiome. We incorporated a more powerful metagenomic shotgun sequencing approach rather than a targeted amplification of the 16S gene for taxonomic assignment of the microbiome. Our results showed no significant differences in the alpha diversity levels between wild and captive black rhinos, but significant differences in beta diversity. We found that bacterial taxa traditionally associated with ruminant guts of domesticated animals had higher relative abundances in captive rhinos. Our metagenomic sequencing results suggest that unknown gut microbes of wild rhinos are being replaced by those found in conventional human-domesticated livestock. Wild rhinos have significantly different functional bacterial communities compared to their captive counterparts. Functional profiling results showed greater abundance of glycolysis and amino acid synthesis pathways in captive rhino microbiomes, representing an animal receiving sub-optimal nutrition with a readily available source of glucose but possibly an imbalance of necessary macro and micronutrients. Given the differences observed between wild and captive rhino gut microbiomes, we make a number of recommendations for potentially modifying captive gut microbiome to better reflect their wild counterparts and thereby hopefully improve overall rhino health in captivity.
- ItemReference Intervals for Hematology and Clinical Chemistry for the African Elephant (Loxodonta africana)(Frontiers Media S.A, 2021-03) Steyrer, Christine; Miller, Michele; Hewlett, Jennie; Buss, Peter; Hooijberg, Emma H.The African elephant (Loxodonta africana) is listed as vulnerable, with wild populations threatened by habitat loss and poaching. Clinical pathology is used to detect and monitor disease and injury, however existing reference interval (RI) studies for this species have been performed with outdated analytical methods, small sample sizes or using only managed animals. The aim of this study was to generate hematology and clinical chemistry RIs, using samples from the free-ranging elephant population in the Kruger National Park, South Africa. Hematology RIs were derived from EDTA whole blood samples automatically analyzed (n = 23); manual PCV measured from 48 samples; and differential cell count results (n = 51) were included. Clinical chemistry RIs were generated from the results of automated analyzers on stored serum samples (n = 50). Reference intervals were generated according to American Society for Veterinary Clinical Pathology guidelines with a strict exclusion of outliers. Hematology RIs were: PCV 34–49%, RBC 2.80–3.96 × 1012/L, HGB 116–163 g/L, MCV 112–134 fL, MCH 35.5–45.2 pg, MCHC 314–364 g/L, PLT 182–386 × 109/L, WBC 7.5–15.2 × 109/L, segmented heterophils 1.5–4.0 × 109/L, band heterophils 0.0–0.2 × 109/L, total monocytes 3.6–7.6 × 109/L (means for “regular” were 35.2%, bilobed 8.6%, round 3.9% of total leukocytes), lymphocytes 1.1–5.5 × 109/L, eosinophils 0.0–0.9 × 109/L, basophils 0.0–0.1 × 109/L. Clinical chemistry RIs were: albumin 41–55 g/L, ALP 30–122 U/L, AST 9–34 U/L, calcium 2.56–3.02 mmol/L, CK 85–322 U/L, GGT 7–16 U/L, globulin 30–59 g/L, magnesium 1.15–1.70 mmol/L, phosphorus 1.28–2.31 mmol/L, total protein 77–109 g/L, urea 1.2–4.6 mmol/L. Reference intervals were narrower than those reported in other studies. These RI will be helpful in the future management of injured or diseased elephants in national parks and zoological settings.