Research Articles (Centre for Veterinary Wildlife Studies)

Permanent URI for this collectionhttp://hdl.handle.net/2263/10642

Browse

Now showing 1 - 20 of 175

Mosquitoes then and now : culicine mosquito research in and around Ndumo Game Reserve, KwaZulu-Natal
Thompson, P.N. (Peter N.); Guarido, Milehna M.; Kemp, Alan (Southern African Wildlife Management Association, 2025-02)
The exceptional biodiversity of the Ndumo area and Maputaland in general, with its tropical biota, is reflected in the high diversity of culicine mosquitoes occurring in the area and, along with their vectors, a high diversity of arthropod-borne viruses (arboviruses). Research interest in the area was driven by the need to identify risks associated with the occurrence of arboviruses potentially affecting human and livestock health in the area, as well as the risk of introduction of arboviruses from elsewhere. We give an overview of the mosquito and arbovirus-related research that has taken place at Ndumo and elsewhere along the lower Phongolo River floodplain since the first expedition in 1955. Intensive work was done on mosquitoes and arboviruses for about 15 years, after which a period of 45 years saw only one focused mosquito study (1989-1993). More recently, interest was inspired once again by the threat of emerging and re-emerging arboviruses and we have been studying culicine mosquitoes and their associated viruses in the Ndumo area since 2016. We describe our recent findings with respect to occurrence and abundance of culicine mosquito species, compare them to historical findings, discuss possible reasons for apparent changes observed, and propose priorities for future research in the area.
Methionine, threonine and glutamic acid adapted pathways in captive cheetahs on a glycine-supplemented diet
Van Boom, Kathryn Merle; Kohn, Tertius Abraham; Tordiffe, Adrian Stephen Wolferstan (Springer, 2025-04-23)
BACKGROUND : Captive cheetahs are prone to a range of unusual diseases potentially linked to unnatural diets high in muscle meat and low in collagen-rich animal fibre. In the wild, cheetahs typically eat whole prey diets not easily replicated in a captive setting. Glycine is the most abundant amino acid in collagen with a key role in several metabolic pathways such as collagen biosynthesis. Several recent studies suggest that endogenous glycine production may be limited in several species. OBJECTIVES : Using untargeted 1H- nuclear magnetic resonance, the metabolic changes in the urine and serum of 10 adult captive cheetahs on a glycine-supplemented diet were investigated. METHODS : Cheetahs were fed either a meat only (control) or glycine-supplemented meat diet (30 g glycine per 1 kg meat) for four weeks, followed by a four-week cross-over. Urine and blood samples were collected at baseline and after each intervention. RESULTS : A total of 151 and 60 metabolites were identified in the urine and serum, respectively. Specifically, dimethylsulphone, proline, fructose, dimethylamine, trimethylamine, pyroglutamic acid, 1,3-diaminopropane, dihydrothymine, methylmalonic acid and pimelic acid contributed to metabolome differences in the urine. In serum, glutamic acid, threonine, α-aminobutyric acid, glucose-6-phosphate, ethanolamine, methionine and propionic acid were highlighted. These metabolites play various metabolic roles in energy production, immune function, protein and collagen biosynthesis or as products of gut microbiome fermentation. CONCLUSION : Glycine supplementation influenced threonine sparing, pyrimidine biosynthesis pathways and bacterial fermentation products, although the implications of these findings on the health of captive cheetahs is unknown. Future studies should use a targeted approach to further elaborate on these pathways.
Multi-locus sequence analysis of Anaplasma in the common warthog (Phacochoerus africanus) from South Africa
Rea, Keaton; Buss, Peter Erik; Bastos, Armanda D.S. (Elsevier, 2025-12)
The prevalence and diversity of Anaplasma in common warthog (Phacochoerus africanus) was investigated using a multi-locus sequence analysis (MLSA) approach targeting the 16S rRNA, citrate synthase (gltA) and heat-shock operon (groESL) genes. PCR screening of 100 warthog samples from the Kruger National Park in South Africa with eight published assays identified 50 positive animals, all of which were initially identified with the 16S rRNA assay. In contrast, the gltA and six groESL assays recovered PCR-positivity rates of 2 % and 0 %-4 %, respectively. As optimisation did not improve Anaplasma detection rates, an alternative groESL assay targeting a 923 bp region was designed. This new assay detected 45 positive animals, all of which were positive with the 16S rRNA assay. Nucleotide sequencing of the three MLSA gene targets confirmed that 50 % (50/100) of warthogs were Anaplasma-positive. Juvenile warthogs displayed a significantly higher infection rate (15/18; 83.3 %) than adults (35/82; 42,68 %). Phylogenetic analyses of individual and concatenated gene datasets confirmed that the Anaplasma species in warthogs is closely related to the species detected in Ornithodoros soft ticks from Zambia. This, together with the high levels of nucleotide sequence identity (≥98.97 %), suggests the likely existence of a host-restricted cycle involving warthogs and the soft ticks that inhabit their burrows. Based on the distinctiveness and monophyly of the Anaplasma species in warthogs and Ornithodoros soft ticks, confirmed through genetic characterisation of three gene regions, we propose that Candidatus status be assigned and suggest “Candidatus Anaplasma ornithodorii”. HIGHLIGHTS • Overall sequence-confirmed Anaplasma prevalence of 50 % in warthogs. • Three gene regions (16S rRNA, gltA and groEL) were characterised. • Anaplasma species in warthogs matches species detected in Ornithodoros soft ticks.
How long limbs reduce the energetic burden on the heart of the giraffe
Seymour, Roger S.; Snelling, Edward P. (Company of Biologists, 2025-10)
Adult giraffes have high mean systemic arterial blood pressure (MAP) of 200–250 mmHg at heart level, which is more than twice that of most mammals. The high MAP is associated with their long neck, because gravity creates a hydrostatic pressure gradient along the carotid arteries such that every metre of height requires an additional 77 mmHg of blood pressure at heart level, and the head can be over 2 m above the heart. The giraffe’s MAP remains high regardless of posture or level of activity, so it creates a significant and unrelenting energy burden on the heart. This study quantifies that burden. Because of high MAP, the energy expenditure of the left ventricle is approximately 16% of the resting whole-body metabolic rate of an adult giraffe, compared with 9% in a normal mammal of the same body mass and a shorter neck. A numerical model is presented that varies the vertical position of the heart in a giraffe’s body of fixed height and recalculates the energy used by the left ventricle. If the giraffe had evolved its height by extending the neck alone without elongating the limbs, the estimated cost would be 21%. However, the long limbs, which predate the long neck in giraffe evolution, have raised the level of the heart, thus reducing the required MAP and saving energy. The vertical distance between the heart and the erect head of adult giraffes appears to be the maximum ever evolved among terrestrial vertebrates.
Does cooling affect skeletal muscle glycogen replenishment after an acute bout of fear-induced exertional hyperthermia in blesbok (Damaliscus pygargus phillipsi)?
Kohn, Tertius Abraham; Martin, Mahmooda; Van Boom, Kathryn Merle; Donaldson, Byron; Blackhurst, Dee M.; Fitte, Agustina; Burroughs, Richard; Steyl, Johan Christian Abraham; Goddard, Amelia; Meyer, Leith Carl Rodney (Elsevier, 2025-11)
Rhabdomyolyses is a clinical sign of capture myopathy in wild animals and may be linked to glycogen metabolism. To study potential mechanisms, 26 wild blesbok were chased for 15 min and immobilised, whereafter 12 of these blesbok were doused with ice-water (n = 14 chased only group; n = 12 chased + cooled group). An additional 12 blesbok served as resting (not chased) uncooled controls. Vastus lateralis biopsies were obtained after immobilisation for biochemical analyses. Biopsies obtained at initial capture, 3- and 16-days post exercise were analysed for glycogen content. Blesbok muscles contained predominantly myosin heavy chain (MHC) IIA (∼50 ± 9 %), followed by IIX (32 ± 10 %) and MHC I (18 ± 5 %), with no difference between groups. Citrate synthase (mean: 87 ± 48), 3-hydroxyacetyl co A dehydrogenase (47 ± 17), lactate dehydrogenase (1567 ± 654), phosphorylase (162 ± 94), phosphofructokinase (250 ± 123) and creatine kinase (12,455 ± 6372) activities (in μmol/min/g prot) were not different between groups. Similarly, superoxide dismutase (7.9 ± 7 U/mg prot), catalase (8.8 ± 5.8 mmol/min/g prot), and overall antioxidant capacity (ORAC: 23055 ± 18,460 μmol/g prot) were not different between groups. Glycogen content was reduced in both chased groups and not replenished by day 3. Glycogen supercompensation was observed on day 16 in both chased groups (∼33 % higher than resting control group). The results confirm that blesbok have high muscle metabolic capacities, and that glycogen resynthesis is slow, which could lead to metabolite deficiency during prolonged chase events (>15 min).
Co-production and conservation physiology : outcomes, challenges and opportunities arising from reflections on diverse co-produced projects
Cooke, Steven J.; Bett, Nolan N.; Hinch, Scott G.; Adolph, Chief Bonnie; Hasler, Caleb T.; Howell, Bradley E.; Schoen, Alexandra N.; Mullen, Eric J.; Fangue, Nann A.; Todgham, Anne E.; Cheung, Melanie J.; Johnson, Rachel C.; Olstad, Rebekah Sze-Tung; Sisk, Marine; Sisk, Chief Caleen; Franklin, Craig E.; Irwin, Robert C.; Irwin, Terri R.; Lewandrowski, Wolfgang; Tudor, Emily P.; Ajduk, Hayden; Tomlinson, Sean; Stevens, Jason C.; Wilcox, Alana A.E.; Giacinti, Jolene A.; Provencher, Jennifer F.; Dupuis-Smith, Reyd; Dwyer-Samuel, Frederic; Saunders, Michelle; Meyer, Leith Carl Rodney; Buss, Peter Erik; Rummer, Jodie L.; Bard, Brittany; Fuller, Andrea (Oxford University Press, 2025-07)
As a relatively nascent discipline, conservation physiology has struggled to deliver science that is relevant to decision-makers or directly useful to practitioners. A growing body of literature has revealed that co-produced research is more likely to generate knowledge that is not only relevant, but that is also embraced and actionable. Co-production broadly involves conducting research collaboratively, inclusively, and in a respectful and engaged manner—spanning all stages from identifying research needs to study design, data collection, interpretation and application. This approach aims to create actionable science and deliver meaningful benefits to all partners involved. Knowledge can be co-produced with practitioners/managers working for regulators or stewardship bodies, Indigenous communities and governments, industry (e.g. fishers, foresters, farmers) and other relevant actors. Using diverse case studies spanning issues, taxa and regions from around the globe, we explore examples of co-produced research related to conservation physiology. In doing so, we highlight benefits and challenges while also identifying lessons for others considering such an approach. Although co-production cannot guarantee the ultimate success of a project, for applied research (such as what conservation physiology purports to deliver), embracing co-production is increasingly regarded as the single-most important approach for generating actionable science to inform conservation. In that sense, the conservation physiology community would be more impactful and relevant if it became commonplace to embrace co-production as demonstrated by the case studies presented here. LAY SUMMARY This article aims to highlight successful applications of co-production within the realm of conservation physiology. Relying on the diverse experiences of co-authors, we also offer guidance to those embracing co-production in their conservation physiology projects.
Occurrence of tick-borne haemoparasites in South African rodent species evidence of Babesia microti-like sequence variants in two Rhabdomys species
Troskie, Milana; Matthee, Sonja; Penzhorn, Barend Louis; Jansen, Raymond; Oosthuizen, Marinda C. (Elsevier, 2025-04)
In recent years, vector-borne viral, bacterial and parasitic diseases have emerged or re-emerged in many geographic regions, causing health and economic problems. Wildlife can act as reservoirs for many human and livestock diseases and that arthropods are often involved in the transmission of these pathogens. Little is known about the zoonotic pathogens that naturally occur in wild rodent and insectivorous shrew species in South Africa. The aims of the study were to: 1) record the tick-borne haemoparasite diversity associated with rodents and shrews at several localities in South Africa, and 2) characterise Babesia microti that occur in rodents using Sanger sequencing of the parasite 18S ribosomal RNA (rRNA) gene and internal transcribed spacer region 1 (ITS1). Nine wild rodent genera (species: n = 412) and two insectivorous shrew genera (species: n = 11) were simultaneously screened for the presence of Theileria, Babesia, Ehrlichia and Anaplasma species using the Reverse Line Blot (RLB) hybridization assay. The RLB PCR amplicons obtained from Mastomys spp., Micaelamys namaquensis, Mus musculus, Rhabdomys dilectus and R. pumilio hybridized with the following RLB species-specific probes: Babesia microti (11.3%), Anaplasma bovis (3.5%), Anaplasma phagocytophilum (1.8%) and Ehrlichia ruminantium (3.5%). The near full-length 18S rRNA gene and partial ITS1 spacer region of 12 of the specimens were cloned and the recombinants sequenced. Babesia microti-like 18S rDNA and ITS1 sequence variants were recorded in two rodent species (Rhabdomys dilectus and Rhabdomys pumilio). The B. microti-like 18S rDNA sequence variants, obtained in this study, clustered phylogenetically within the established B. microti-like clade (Clade I). Nevertheless, they formed a distinct South African group that seems to differ significantly from B. microti sensu stricto and could potentially represent a fifth distinct lineage within the B. microti-like clade.The study highlights the potential of small mammals acting as important reservoirs for vector-borne haemoparasites in South Africa. HIGHLIGHTS • Most extensive study on haemoparasites associated with small mammals in Southern Africa to date. • 63.3% rodent samples positive for Theileria/Babesia/Ehrlichia/Anaplasma DNA. • Regional-specific Babesia microti-like sequence variants recorded in two commensal and wide-spread rodent species.
Outbreaks of H5N1 high pathogenicity avian influenza in South Africa in 2023 were caused by two distinct sub-genotypes of clade 2.3.4.4b viruses
Abolnik, Celia; Roberts, Laura Christl; Strydom, Christine; Snyman, Albert; Roberts, David Gordon (MDPI, 2024-06)
In 2023, South Africa continued to experience sporadic cases of clade 2.3.4.4b H5N1 high-pathogenicity avian influenza (HPAI) in coastal seabirds and poultry. Active environmental surveillance determined that H5Nx, H7Nx, H9Nx, H11Nx, H6N2, and H12N2, amongst other unidentified subtypes, circulated in wild birds and ostriches in 2023, but that H5Nx was predominant. Genome sequencing and phylogenetic analysis of confirmed H5N1 HPAI cases determined that only two of the fifteen sub-genotypes that circulated in South Africa in 2021-2022 still persisted in 2023. Sub-genotype SA13 remained restricted to coastal seabirds, with accelerated mutations observed in the neuraminidase protein. SA15 caused the chicken outbreaks, but outbreaks in the Paardeberg and George areas, in the Western Cape province, and the Camperdown region of the KwaZulu-Natal province were unrelated to each other, implicating wild birds as the source. All SA15 viruses contained a truncation in the PB1-F2 gene, but in the Western Cape SA15 chicken viruses, PA-X was putatively expressed as a novel isoform with eight additional amino acids. South African clade 2.3.4.4b H5N1 viruses had comparatively fewer markers of virulence and pathogenicity compared to European strains, a possible reason why no spillover to mammals has occurred here yet.
Antibiotic resistance profiles of oral flora in hippopotami (Hippopotamus amphibius) : implications for treatment of human bite wound infections
Michel, Anita Luise; Engelbrecht, Maralize; Roux, Francois; Wentzel, Jeanette Maria; Jonker, Annelize (BioMed Central, 2025-04)
BACKGROUND : The common hippopotamus (Hippopotamus amphibius) is found in aquatic environments throughout sub-Saharan Africa and is known to cause attacks on humans living or working close to water bodies. Victims surviving an attack often suffer from the consequences of severe wound infections caused by the animal’s sharp canine teeth. OBJECTIVE : Isolation of normal flora bacteria from the oral cavity of common hippopotami (Hippopotamus amphibious) followed by antibiotic susceptibility testing to aid in the identification of a targeted antibiotic treatment regimen for hippopotamus attack victims. METHODS : Oral swabs were collected from 34 free-ranging hippopotami in three reserves within the Greater Kruger National Park Complex in South Africa and cultured for aerobic and anaerobic bacteria. Antibiotic susceptibility testing was conducted using the disc diffusion method (Kirby-Bauer method) and a panel of 16 antibiotic drugs representing 10 antibiotic categories. RESULTS : Culturing of 50 oral swab samples from 34 hippopotami yielded 188 aerobic isolates belonging to 30 bacterial genera and 41 bacterial species (Gram-negative: 70.7%; Gram-positive: 29.3%) and 16 obligate anaerobic isolates from two genera. Three bacterial species, namely Aeromonas hydrophila, Aeromonas sobria and Shewanella putrefaciens accounted for 52% of the aerobic isolates. The anaerobic isolates were identified as Prevotella melaninogenica and Clostridium spp. Antimicrobial susceptibility testing was performed for 112 aerobic isolates (Gram-negative: 93 (83%); Gram-positive: 19 (17%)) representing all isolated bacterial species. High levels of antibiotic resistance were observed among the Gram-negative species especially to most beta-lactam antibiotics (50.5% to 80.7%). Multidrug resistance was detected in 22.6% of Gram-negative isolates and in 24.1% of all isolates. CONCLUSIONS : This study provides the first investigation of the oral flora bacteria of the common hippopotamus. Among the 32 mostly aerobic bacterial genera the most abundant bacterial species were A. hydrophila, A. sobria and S. putrefaciens. They are typical inhabitants of the aquatic habitat of the hippopotamus and of zoonotic importance as opportunistic human pathogens. The antibiotic susceptibility profiles demonstrated that quinolones, aminoglycosides, and tetracyclines were highly efficacious against these bacterial species which otherwise showed moderate to high levels of resistance to the traditional bite wound treatment with amoxicillin/clavulanate and 1st and 2nd generation cephalosporins.
Radiological landmarks as an aid in the interpretation of rodent skull extra-oral projections
Norval, Quintin; Tordiffe, Adrian Stephen Wolferstan; Steenkamp, Gerhardus (Wiley, 2025-05)
Knowledge of the radiographic anatomy of rodent skulls is essential for accurately interpreting extra-oral radiographs, a non-invasive diagnostic tool commonly used in veterinary practice. Due to the complexity of the skull and the potential for distortion in two-dimensional views, a systematic evaluation of anatomical structures is necessary. This study identifies the most clinically relevant anatomical landmarks on standard extra-oral radiographic views of the skull and mandible in various rodent species, including a cane rat, two woodchucks, and seven common mole rats. Specimens were evaluated with bone and soft tissue intact, as well as dried skulls, to identify key anatomical features. The findings highlight distinct species-specific variations despite general similarities in skull structure. These landmarks were catalogued to aid veterinary professionals in interpreting rodent radiographs. Improved recognition of these structures enhances diagnostic accuracy, enabling better assessment of normal anatomy and potential pathological conditions in rodent patients.
Factors affecting in vitro oocyte maturation in Southern white rhinoceros (Ceratotherium simum simum)
Smuts, Mario P.; De Bruin, P.R.; Fosgate, Geoffrey Theodore; Vorster, L.; De la Rey, Marlene; Lichtenberg, C.; Young, C.; Durrant, B.S.; Meyer, Leith Carl Rodney; Holm, Dietmar Erik (Medpharm Publications, 2025-05)
BACKGROUND : Population numbers of free-roaming rhinoceros are dwindling while natural breeding in captive populations is challenged by sub-optimal fertility. When natural breeding programmes fail and population numbers continue to decline, the use of assisted reproduction technologies (ART) as a conservation tool to save wildlife species from extinction is imperative. Assisted breeding programmes in rhinoceros are challenging and attempts to develop species-specific ART beyond artificial insemination have been limited. This study evaluates various ex- and in-situ factors that could potentially affect in vitro oocyte maturation (IVM) in the Southern white rhinoceros (SWR). OBJECTIVES : To identify predictors of oocyte maturation following ovum pick-up (OPU) procedures performed on a large number of rhinoceros under different management conditions. METHODS : Data from 85 OPU procedures between November 2018 and June 2023 were obtained for this study. A total of 23 factors (three animal, four environmental, 16 laboratory) were evaluated as potentially affecting IVM success. RESULTS : Of the 85 procedures performed on 59 SWR, a total of 265 oocytes were collected with a median of two oocytes (range 0–18) per OPU. Eighteen (18) of the procedures yielded 0 oocytes. The overall maturation rate was 30% (80/265), and six identified factors had significant univariate associations with maturation outcome, of which three remained in the multivariable model. CONCLUSION : Farming system, season and oocyte density in maturation medium (> 100 ul/oocyte) were independently associated with improved maturation success (p < 0.05).
Accidental intravenous overdose of meloxicam in a Cape Vulture (Gyps coprotheres)
Gazendam, Bart Adriaan Theodorus; Koeppel, Katja Natalie (Medpharm Publications, 2025-02)
Many species of vulture are under threat from man-made inventions; this has led to wounded and sick vultures presenting for veterinary treatment and in need of pain management. Following the devastating effect of diclofenac on vultures in South Asia, meloxicam was found to be very safe for vultures, as a treatment as well as through ingestion of meat from treated animals. Many studies investigated the safety of meloxicam, and all found it to be safe up to 2 mg/kg, which was deemed the maximum likely exposure through treated carcasses. All studies exposed the birds either through oral dosing, treated meat or intramuscular administration, no instances of toxicity where recorded and all birds remained healthy. In this case the bird was exposed to a single dose of 2 mg/kg, intravenously, with no signs of toxicity. This appears to be the first recorded instance of accidental intravenous administration of meloxicam in a vulture.
Revisiting concepts of thermal physiology : understanding feedback and feedforward control, and local temperature regulation
Mitchell, Duncan; Maloney, Shane K.; Snelling, Edward P.; Hetem, Robyn S.; Fuller, Andrea (Wiley, 2025-07)
Most experts agree that the dominant mechanism through which body temperature is regulated, under a thermal challenge, environmental or metabolic, is negative feedback control. However, some consider negative feedback to be too sluggish to account for the rapid speed of response. The impression of sluggishness is based on an assumption that the body temperature that is regulated is a core temperature, whereas we concur with those who have concluded that what is regulated is an integrated temperature compiled from inputs from multiple body parts, including the skin. Negative feedback control is supplemented, though, by feedforward control, which is initiated by cues about the predicted magnitude and timing of the thermal challenge. Feedforward control is anticipatory because it can excite thermo-effectors in advance of the thermal challenge impacting on body temperature. Feedforward control is improved by learning but always is supervised by feedback control. There is disagreement about whether the pro-active excitation of thermo-effectors by temperature receptors in the skin occurs by fast feedback control or by feedforward control. We show that skin temperature receptors can provide physiologically meaningful negative feedback within seconds. Both the feedback and the feedforward regulation of integrated body temperature can be modulated by regulation of the temperature of body parts that have special thermoregulatory needs, notably the scrotum.
Seasonality, social structure and age predict conspecific aggression in captive breeding southern ground-hornbills (Bucorvus leadbeateri)
Koeppel, Katja Natalie; Lubbe, Nevanya; Donaldson, Ashleigh Claire; Kemp, Lucy Valeska (Wiley, 2025-03)
Southern Ground-hornbills (SGHs) are listed as Vulnerable globally, and Endangered in South Africa, Namibia and Swaziland, due to poisoning, habitat loss and persecution. Successful conservation breeding and rearing of redundant second-hatched chick protocol has been established to supplement natural SGH populations in an attempt mitigate a declining population. However, captive rearing is costly and susceptible to loss of birds through conspecific aggression. Maximising the efficacy of reproductive output in captive settings and ensuring successful reintroductions of captive-reared birds to wild populations is of paramount importance if this species is to persist. Therefore, it is important to untangle the predictors of what drives mortalities in captive birds, particularly, through conspecific aggression. Using a database of captive SGH mortalities collected over 46 years we investigated whether variables such as season, age, relatedness, sex and husbandry predicted the occurrence of conspecific aggression in SGH. Aggression among adult, non-related birds particularly during SGH breeding season (austral spring) was the most predictable form of conspecific aggression. It was inferred that aggression is normally directed at non-related birds outside of already established social groups or at younger, related birds that are not dispersing from groups when reaching sexual maturity. Variables such as season, age, relatedness and husbandry were therefore all useful for predicting the potential and avoidable occurrence of an aggression event. Male birds were most often the aggressors. Making use of such variables to manage birds in a captive setting, move birds before sexual maturity and maintaining birds in known and accepted social structures could greatly improve management in SGH breeding facilities and optimise the efforts for re-establishing natural SGH populations. SUMMARY: Conspecific trauma accounted for approximately 7.80% of all recorded Southern Ground-hornbill (SGH) mortalities. Seasonality significantly influenced aggression, with more attacks in austral spring compared to autumn. Breeding status did not affect aggression frequency; non-breeding individuals were more often involved. Males were not significantly more aggressive than females or pairs, but non-breeding individuals were most aggressive in austral winter and spring. Victim sex or attacker sex did not predict aggression likelihood. Age and sex determined onset of attacks with majority of attacks been adult birds and females (8.8 ± 8.3 years) been attacked earlier then male (9.1 ± 8.9 years). Group size did not significantly influence attack frequency. Moon phase did not affect aggression occurrence.
Two point-of-care cardiac Troponin I immunoassays have acceptable analytical performance for the detection of measurands of cardiac Troponin I cardiac muscle homogenates from southern-central black rhinoceros (Diceros bicornis minor) and southern white Rhinoceros (Ceratotherium simum simum)
Rautenbach, Yolandi; Meyer, Leith Carl Rodney; Goddard, Amelia; Buss, Peter Erik; Hooijberg, Emma Henriette (Wiley, 2025-06)
BACKGROUND : Skeletal and possible cardiac muscle damage has been reported in chemically immobilized and transported African rhinoceros during conservation-related activities. The extent of cardiac muscle injury in these rhinoceros is unknown due to a lack of validated cardiac troponin I (cTnI) assays. However, recently, five human cTnI assays were deemed suitable for analytical validation in African rhinoceros based on cTnI sequencing results. OBJECTIVES : The first objective was to validate two cTnI immunoassay point-of-care analyzers (POCAs) in African rhinoceros and, secondly, to perform quality control (QC) validation for the POCAs. METHODS : Analytical validation of the Stratus CS Acute Care Troponin I cTnI immunoassay and Atellica VTLi high sensitivity cTnI (hs-cTnI) assay was performed using rhinoceros serum samples and species-specific cardiac muscle homogenate. Experiments included precision studies, reportable range, hemoglobin interference studies, recovery studies, and detection limit studies, with results assessed against prescribed total allowable error (TEa) performance goals. Commercial quality control material (QCM) data were used to calculate bias and imprecision for QC validation. RESULTS : Imprecision was acceptable (1.9%-10.3%) and met low cTnI concentration performance goals. Reportable ranges were similar to the manufacturer's specifications. High hemoglobin concentrations in white rhinoceros resulted in a positive bias in the Stratus CS. A simple 13s QC rule using two levels of QCM and a TEa of 70% could be used in both analyzers, except at very low cTnI concentrations in the Atellica VTLi. CONCLUSIONS : Both cTnI POCAs are suitable for use in African rhinoceros, and analytical performance goals for low cTnI concentrations in hs-cTnI assays were met.
Revisiting concepts of thermal physiology : understanding feedback and feedforward control, and local temperature regulation
Mitchell, Duncan; Maloney, Shane K.; Snelling, Edward P.; Hetem, Robyn S.; Fuller, Andrea (Wiley, 2025-07)
Most experts agree that the dominant mechanism through which body temperature is regulated, under a thermal challenge, environmental or metabolic, is negative feedback control. However, some consider negative feedback to be too sluggish to account for the rapid speed of response. The impression of sluggishness is based on an assumption that the body temperature that is regulated is a core temperature, whereas we concur with those who have concluded that what is regulated is an integrated temperature compiled from inputs from multiple body parts, including the skin. Negative feedback control is supplemented, though, by feedforward control, which is initiated by cues about the predicted magnitude and timing of the thermal challenge. Feedforward control is anticipatory because it can excite thermo-effectors in advance of the thermal challenge impacting on body temperature. Feedforward control is improved by learning but always is supervised by feedback control. There is disagreement about whether the pro-active excitation of thermo-effectors by temperature receptors in the skin occurs by fast feedback control or by feedforward control. We show that skin temperature receptors can provide physiologically meaningful negative feedback within seconds. Both the feedback and the feedforward regulation of integrated body temperature can be modulated by regulation of the temperature of body parts that have special thermoregulatory needs, notably the scrotum.
Revisiting concepts of thermal physiology : understanding negative feedback and set-point in mammals, birds, and lizards
Mitchell, Duncan; Fuller, Andrea; Snelling, Edward P.; Tattersall, Glenn J.; Hetem, Robyn S.; Maloney, Shane K. (Wiley, 2025-06)
The thermoregulatory system of homeothermic endotherms operates to attain thermal equilibrium, that is no net loss or gain of heat, where possible, under a thermal challenge, and not to attain a set-point or any other target body temperature. The concept of a set-point in homeothermic temperature regulation has been widely misinterpreted, resulting in such confusion that some thermoregulation specialists have recommended that it be abandoned. But the set-point concept has enjoyed a resurgence in a different domain, lizard microclimate selection. We review the principles of thermoregulation in homeotherms, endorse a negative feedback system with independent set-points for individual thermo-effectors as its core mechanism, and address the misconceptions about homeothermic set-point. We also explore the concept of set-point range in lizard microclimate selection and conclude that there is substantial convergence between that concept and the set-points of homeothermic thermo-effectors, as thresholds. In neither homeothermic nor lizard thermoregulation is the concept of a unitary set-point appropriate. We review the problems of measuring the set-points for lizard microclimate selection. We do not believe that the set-point concept in thermoregulation should be abandoned just because it has been misinterpreted by some users. It is a valid concept, identifying the threshold body temperatures at which regulatory thermo-effectors will be activated, to aid in attaining thermal equilibrium.
Sex-dependent metabolic and behavioural alterations in a rat model of forced exertion-induced myopathy
Lubbe, Crystal; Harvey, Brian H.; Viljoen, Francois P.; Meyer, Leith Carl Rodney; Wolmarans, De Wet (BioMed Central, 2025-03)
Please read abstract in the article.
Phylogenomics of Brucella abortus isolated from African buffalo in Kruger National Park : new perspectives on wildlife-cattle disease dynamics
Cossu, Carlo Andrea; Garofolo, Giuliano; Janowicz, Anna; De Massis, Fabrizio; Wentzel, Jeanette Maria; Ledwaba, Maphuti Betty; Sabeta, Claude Taurai; De Klerk, Lin-Mari; Godfroid, Jacques; Vergnaud, Gilles; Van Heerden, Henriette (Elsevier, 2025-05)
In South Africa, Brucella abortus biovar 1 is the primary cause of bovine brucellosis, significantly impacting cattle production and trade. Serological studies have revealed brucellosis in African wildlife, complicating control efforts due to limited epidemiological data. In 1977, B. abortus biovar 1 was isolated from an African buffalo fetus in Kruger National Park (KNP), raising speculation that buffalo may serve as reservoir hosts. This study investigated Brucella spp. in free-ranging buffalo in KNP using serological, molecular, and bacteriological methods. Brucella abortus bv 1 was isolated from lymph nodes and spleens of three sub-adult buffalo in 2022, marking the first documented recurrence in 50 years. Phylogenomic analyses revealed connections between buffalo isolates and cattle strains from South Africa and South America, suggesting spillover and shared origins from Europe. Further genomic and epidemiological surveillance is required to clarify the role of buffalo as reservoir hosts for brucellosis.
Does sex matter in the cheetah? Insights into the skeletal muscle of the fastest land animal
Kohn, Tertius Abraham; Knobel, Samantha; Donaldson, Byron; Van Boom, Kathryn Merle; Blackhurst, Dee M.; Peart, James M.; Jensen, Jorgen; Tordiffe, Adrian Stephen Wolferstan (Company of Biologists, 2024-08)
The cheetah is considered the fastest land animal, but studies on their skeletal muscle properties are scarce. Vastus lateralis biopsies, obtained from male and female cheetahs as well as humans, were analysed and compared for fibre type and size, and metabolism. Overall, cheetah muscle had predominantly type IIX fibres, which was confirmed by the myosin heavy chain isoform content (mean±s.d. type I: 17±8%, type IIA: 21±6%, type IIX: 62±12%), whereas humanmuscle contained predominantly type I and IIA fibres (type I: 49±14%, type IIA: 43±8%, type IIX: 7±7%). Cheetahs had smaller fibres than humans, with larger fibres in the males compared with their female counterparts. Citrate synthase (16±6 versus 28±7 μmol min−1 g−1 protein, P<0.05) and 3-hydroxyacyl co-enzyme A dehydrogenase (30±11 versus 47 ±15 μmol min−1 g−1 protein, P<0.05) activities were lower in cheetahs than in humans, whereas lactate dehydrogenase activity was 6 times higher in cheetahs (2159±827 versus 382±161 μmolmin−1 g−1 protein, P<0.001). The activities of creatine kinase (4765±1828 versus 6485 ±1298, P<0.05 μmol min−1 g−1 protein) and phosphorylase (111±29 versus 216±92 μmol min−1 g−1 protein) were higher in humans, irrespective of the higher type IIX fibres in cheetahs. Superoxide dismutase and catalase,markers of antioxidant capacity, were higher in humans, but overall antioxidant capacity was higher in cheetahs. To conclude, fibre type, fibre size andmetabolismdiffer between cheetahs and humans, with limited differences between the sexes.

Browse

Recent Submissions