Surgical correction of a persistent right aortic arch in a kitten with concurrent mitral and tricuspid valve insufficiency and long-term post-operative management of residual megaoesophagus

A Maine Coon kitten was diagnosed with persistent right aortic arch and concurrent mitral and tricuspid valve insufficiency. Diuretic and positive inotropic treatment were administered before surgical treatment was attempted. Surgical ligation of the ligamentum arteriosum was performed successfully. Regurgitation did not resolve despite efforts to slowly introduce solid food to the diet over a period of two months. The kitten suffered from several incidences of aspiration pneumonia that responded to antibiotic treatment. Follow-up computed tomography ruled-out extraluminal constriction of the oesophagus, and oesophagoscopy confirmed a residual megaoesophagus six months post-operatively. The kitten was euthanised seven months after surgery. The importance of a complete cardiac work-up and oesophagoscopy in suspected vascular ring anomaly examinations are highlighted in this case study.https://bvajournals.onlinelibrary.wiley.com/journal/205261212022-06-09hj2022Companion Animal Clinical Studie

The Role of Host Traits, Season and Group Size on Parasite Burdens in a Cooperative Mammal

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted

The relationship between immunocompetence, parasite load and reproductive effort in the highveld mole-rat (Cryptomys hottentotus pretoriae) Roberts 1913.

Life-history theory is based on the notion that resources are generally limited in nature, and that organisms have to allocate these resources amongst different physiological systems to maximise their survival and fitness. Therefore life-history traits such as maintenance, growth and fecundity are very often negatively associated with each other. Since the immune system plays a prominent role in fitness and survival of an organism it often features in life-history trade-offs particularly with respect to reproductive effort. This thesis focused predominantly on the interactions between immune function and reproductive effort in the highveld mole-rat, Cryptomys hottentotus hottentotus as well as other factors that may influence these two vital systems. In the first chapter interactions between reproductive effort and immune function in 22 female highveld mole-rats (5 reproductive females and 17 non-reproductive females) is investigated by stimulating reproductive competition amongst females within colonies and monitoring hormonal and haematological parameters. Behavioural observations focusing on agonistic, grooming and sexual behaviour is also included in this chapter mostly as tool to identify reproductive competition amongst females. The second chapter deals specifically with the effect of the season, gender and reproductive status on a febrile response to an exogenously administered pyrogen. Lipopolysaccharide, a protein produced by gram negative bacteria, was used to induce fever in 37 mole-rats during both winter and summer months. The final chapter explored the relationships between parasite infestation and host gender and reproductive status while concurrently identifying some of the parasites associated with the highveld mole-rat. A total of 46 mole-rats were assessed for intensity of gastrointestinal parasites, 131 for prevelance of cestodes by faecal examination and 85 for intensity and prevalence of ectoparasites. A possible relationship between host group size and intensity of parasitism is explored. Seasonal patterns of the parasites found is also investigated and related to possible seasonal variation in immune function.Dissertation (MSc)--University of Pretoria, 2011.Zoology and EntomologyUnrestricte

Life-history traits, but not season, affect the febrile response to a lipopolysaccharide challenge in highveld mole-rats

Fever is part of an acute phase response that organisms launch to defend themselves against an invasion by microbial pathogens such as bacteria and viruses. The elevation of an individual’s body temperature necessary to achieve a fever is considered energetically costly and variation in the expression of the febrile response has been reported with respect to season, sex and the reproductive status of an animal. The effect of these parameters on fever responses are well characterized for laboratory rodents but comparable data from wild rodents are currently lacking. We evaluated the febrile response of wild highveld mole-rats (Cryptomys hottentotus pretoriae) to lipopolysaccharide (LPS) during winter and summer. This social rodent retains its breeding potential throughout the year and exhibits a reproductive division of labour. Highveld mole-rats increased their body temperature to a greater degree in response to a dose of 1 mg kg-1 LPS than to saline or handling alone. The fever response did not differ between seasons while the stress-induced hyperthermia in response to handling was greater in summer compared winter. In contrast, males and breeders exhibited larger changes in body temperature following LPS administration than females and non-breeders, respectively. These findings are in accordance with those reported for laboratory species and suggest that general principles govern the modulation of innate immune responses such as fever among small mammals.This project was funded by the DST-NRF South African Research Chair for Behavioural Ecology and Physiology to NCB. In addition, HL acknowledges funding through a Research Fellowship by the University of Pretoria. The research was approved by the Ethics Committee of the University of Pretoria (EC004-08).http://www.blackwellpublishing.com/pdf/jzo_elf.pdfnf201

Comparative antimicrobial efficacy of 4 surgical-hand-preparation procedures prior to application of alcohol-based hand rub in veterinary students

OBJECTIVE: To determine the influence of skin preparations before application of an alcohol-based hand rub (ABHR) on bacterial counts before and after elective surgery. STUDY DESIGN: Clinical prospective study. SAMPLE POPULATION: Veterinary students (n=103) performing ovariohysterectomies on 140 dogs. METHODS: Participants were randomly assigned to 1 initial surgical preparation on the day of surgery: A–hand preparation with medicated solution (4% w/v chlorhexidine bigluconate followed by an ABHR; B–application of a medication solution (benzalkonium chloride 0.1%-1%and polymeric biguanide hydrochloride0.01%-0.1%) followed by an ABHR; C–nonmedicated pH-neutral soap hand wash followed by ABHR, and D–direct application of an ABHR. Samples were taken by pressing the distal finger tips to an agar plate before the hand preparation, after the hand preparation (n=3), after ABHR application, and 120 minutes later. Colony-forming units (CFUs) for samples were determined. Total log CFU and CFU log10 reduction were calculated and used for comparison with P<.05. RESULTS: Two hours after surgery commenced, the participants of groups that performed a hand preparation had lower total CFUs than those that did not perform a hand preparation (P=.001). In particular, the number of CFUs was lower when ABHR was performed after application of pHN compared to direct ABHR (P=.001). CONCLUSION: In this population, performing a hand preparation with pHN prior to applying an ABHR had better antimicrobial effect for the duration of surgery than not performing a hand preparation. CLINICAL SIGNIFICANCE: Surgeons should wash their hands prior to ABHR before starting their first surgery of the day, even when hands appear clean.Companion Animal Clinical Studies Research Fund of the University of Pretoria; South African Veterinary Foundation.http://wileyonlinelibrary.com/journal/vsu2023-02-22pm2022Companion Animal Clinical StudiesProduction Animal Studie

Efavirenz plasma concentrations at 1, 3, and 6 months post-antiretroviral therapy initiation in HIV type 1-infected South African children

The aim of this study was to quantify the plasma efavirenz concentrations over 6 months in black HIV-1-infected South African children (3–14 years), from resource-limited households, attending an outpatient clinic. The children were antiretroviral treatment (ART) naive and received efavirenz in combination with two nucleoside reverse transcriptase inhibitors according to South African national guidelines. Two blood samples were taken between 12 and 20 h after the last efavirenz dose at 1 ( n ¼ 58), 3 ( n ¼ 54), and 6 ( n ¼ 54) months post-ART initiation. A total of 328 efavirenz mid-dose plasma samples from 58 patients was determined with a validated liquid chromatography tandem mass spectrometry method. Viral suppression ( < 25 copies = ml) was achieved in 95% of the children after 6 months on ART. The median (range) plasma concentration at time points 1 and 2 were 2.06 (0.10–11.14) and 1.80 (0.14–10.70) m g = ml with respective mean ( SD) blood sampling times of 15.24 (2.03) and 16.91 (2.03) h post-evening dose. Efavirenz plasma samples within the therapeutic range of 1–4 m g = ml accounted for 58%; 17% were < 1 m g = ml and 25% were > 4 m g = ml over the 6 months. Efavirenz levels persistently > 4 m g = ml were recorded for 13 (23%) children and 3 (5%) children had persistent efavirenz levels < 1 m g = ml. Possible reasons for efavirenz plasma levels outside the accepted therapeutic range include genetic variation in drug metabolism, incorrect dosing, drug–drug interactions, and nonadherence. However, these need to be further explored and the importance of sequential plasma levels has been highlighted in this stud

The role of host traits, season and group size on parasite burdens in a cooperative mammal

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted.This project was funded by the DST-NRF (Department of Science and Technology - National Research Foundation) South African Research Chair for Behavioural Ecology and Physiology to NC Bennett.http://www.plosone.orgab201

Socially induced infertility in Ansell's mole-rat : are there depressed hormone levels in non-reproductive males and females?

Ansell’s mole-rat, Fukomys anselli, is a social subterranean mammal and exhibits an extreme reproductive division of labour. Reproduction in the colony appears to be restricted usually to a single female. Complete colonies captured throughout an entire calendar year were euthanased and the histology of the gonads and plasma hormone concentrations were measured in reproductive and non-reproductive members of both sexes. In males, the circulating levels of testosterone were highest in the reproductive male. The mean testes mass for male corrected for body mass was lower than that of the non-reproductive male. However, the mean testes volume of reproductive males was greater than that for the non-reproductive males and the seminiferous tubule diameter was greater in reproductive males. Reproductive females characteristically possessed corpora lutea of ovulation and pregnancy in their ovaries and this was met with much elevated progesterone concentrations in these females. In contrast, non-reproductive females showed a complete range of follicular genesis, but they did not possess corpora lutea of ovulation or pregnancy, in turn they show depressed progesterone concentrations. The current available evidence suggests that in Ansell’s mole-rats, the non-reproductive males and females refrain from sexual activity by being subordinate and moreover related to the breeding pair.The research was funded by the SARCHI Chair of mammal behavioural ecology and physiology from the Department of Science and Technology and the National Research Foundation, South Africa (to N.C Bennett). We also acknowledge a bursary from the NRF (to P.R de Bruin).http://www3.interscience.wiley.com/journal/118535410/home-8369nf201

Summary of the parasites found and their infection parameters in highveld mole-rats.

<p>Summary of the parasites found and their infection parameters in highveld mole-rats.</p