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Multi-kingdom characterization of the core equine fecal microbiota based on multiple equine (sub)species

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Joan E. Edwards, S. A. Shetty, P. van den Berg, Faith A. Burden, D. A. van Doorm, W. F. Pellikaan, J. Dijkstra, H. Smidt. 12 February 2020. Multi-kingdom characterization of the core equine fecal microbiota based on multiple equine (sub)species. Animal Microbiome. 2:6.

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Publication date: 
12 February 2020
Journal: 
Animal Microbiome
Volume: 
2
Issue: 
6
DOI number: 
10.1186/s42523-020-0023-1
Abstract

Background: Equine gut microbiology studies to date have primarily focused on horses and ponies, which represent only one of the eight extant equine species. This is despite asses and mules comprising almost half of the world’s domesticated equines, and donkeys being superior to horses/ponies in their ability to degrade dietary fiber. Limited attention has also been given to commensal anaerobic fungi and archaea even though anaerobic fungi are potent fiber degrading organisms, the activity of which is enhanced by methanogenic archaea. Therefore, the objective of this study was to broaden the current knowledge of bacterial, anaerobic fungal and archaeal diversity of the equine fecal microbiota to multiple species of equines. Core taxa shared by all the equine fecal samples (n = 70) were determined and an overview given of the microbiota across different equine types (horse, donkey, horse × donkey and zebra). Results: Equine type was associated with differences in both fecal microbial concentrations and community composition. Donkey was generally most distinct from the other equine types, with horse and zebra not differing. Despite this, a common bacterial core of eight OTUs (out of 2070) and 16 genus level groupings (out of 231) was found in all the fecal samples. This bacterial core represented a much larger proportion of the equine fecal microbiota than previously reported, primarily due to the detection of predominant core taxa belonging to the phyla Kiritimatiellaeota (formerly Verrucomicrobia subdivision 5) and Spirochaetes. The majority of the core bacterial taxa lack cultured representation. Archaea and anaerobic fungi were present in all animals, however, no core taxon was detected for either despite several taxa being prevalent and predominant. Conclusions: Whilst differences were observed between equine types, a core fecal microbiota existed across all the equines. This core was composed primarily of a few predominant bacterial taxa, the majority of which are novel and lack cultured representation. The lack of microbial cultures representing the predominant taxa needs to be addressed, as their availability is essential to gain fundamental knowledge of the microbial functions that underpin the equine hindgut ecosystem.

Full article available open access.

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Preliminary investigation into relationships between donkey and horse skull morphology and brain morphology

Citation

K. Merkies, Georgios Paraschou, P. D. McGreevy. 23 November 2017. Preliminary investigation into relationships between donkey and horse skull morphology and brain morphology. Presented at 13th International Equitation Science Conference. (22 November - 25 November 2017). Wagga Wagga, New South Wales, Australia.

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Date presented: 
Thursday 23 November 2017
Abstract

All horses and donkeys belong to the genus Equus but anatomical and behavioural differences exist among species. Equus caballus displays distinctive conformational attributes among breeds provisionally related to ganglion cell distribution and skull and brain morphology. Equus asinus shows less variation in skull shape, and little is known about brain organisation. The current research compared skull and brain morphology between horses and donkeys. Skulls of Equus caballus, primarily of Standardbred type (N=14) and Equus asinus (N=16), were obtained postmortem. All animals had been humanely euthanised for reasons unrelated to this study. Heads were sectioned sagitally along the midline and photographed for measurement of various skull structures using Image J software. Measurements included: skull index (SI)=zygomatic width*100/skull length; cranial index (CI)=cranial width*100/cranial length; nasal index (NI)=zygomatic width*100/nasal length; cranial profile index (CPI)=rectangular area bordered by an 80mm line from orbital notch and occiput; nasal profile index (NPI)= rectangular area bordered by 80mm line from orbital notch and tip of nasal bone; olfactory lobe area (OLA); OL pitch [angle between hard palate and the OL axis]; brain pitch [angle between longitudinal axis of the cerebral hemispheres and the hard palate]; and whorl location (WL) [distance of OL from the level of the forehead whorl]. A General Linear Model determined the main effect of species with Sidak’s multiple comparisons of species’ differences among the various measurements. Donkeys had shorter heads (cranial lengths) than horses (19.7±2.5 vs 23.6±1.4cm respectively; F1,23=51.49, P<0.0002). Donkeys also had smaller cranial widths (13±3.4cm; F1,17=15.91, P<0.001) and mandibular depths (24±2.6cm; F1,21=13.05, P<0.002) than horses (19±0.8 and 27.2±1.1cm, respectively). There was no species difference in SI, ZI, or NI (P>0.40), but donkeys tended to have a smaller CI than horses (F1,17=3.59, P<0.08). Similarly, donkeys had a smaller CPI than horses (F1,21=7.54, P<0.034), but there was no difference in NPI (F1,21=0.05, P>0.83). Donkeys also had a smaller OLA than horses (1.4±0.3 vs 2.3±1.3cm2 respectively; F1,13=4.96, P<0.05) although there was no difference in brain pitch (F1,23=0.69, P>0.43). The greatest difference was seen in WL, which corresponded to the level of the OL in horses, but was extremely rostral in donkeys (F1,21=24.29, P<0.0001). These results show clear differentiation in skull morphology between horses and donkeys which may be linked to behaviour. This may be useful in validating different approaches in the training and management of horses versus donkeys.

Lay person message: Horses demonstrate specific behaviours which may be associated with skull shape, although nothing is known about this relationship in donkeys. This pilot study has shown that donkeys have smaller brain cases and olfactory lobes than Standardbred horses. Donkeys’ facial whorls are located lower down the face while horses’ are in close proximity to the brain’s olfactory lobe. Clarifying differences between horses and donkeys is crucial to understanding species-specific behavioural responses and providing appropriate management and training practices.

Nutritional management of Hyperlipaemiam

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Andy Durham, Alexandra K. Thiemann. 26 May 2015. Nutritional management of Hyperlipaemiam. Equine Veterinary Education.

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Publication date: 
26 May 2015
DOI number: 
10.1111/eve.12366
Abstract

Hyperlipaemia is a disease resulting from excessive mobilisation of triglyceride stores such that plasma clearance processes become overwhelmed. Consequently increased plasma triglyceride concentrations (>5.6 mmol/l), visibly cloudy plasma and a sick, anorexic or hypophagic subject follow. Epidemiological studies have identified many predisposing and triggering factors and the attentive carer or veterinary surgeon should be alert to such risk factors so that the disease can be prevented, or at least identified and treated at an early stage. Hyperlipaemic subjects are invariably in a negative energy balance, and nutritional management therefore plays a central role in both the prevention and resolution of the disease.

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Trypanosomosis in working equids in West Africa: characterising neurological disease

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Demelza Kingston, Jan Rodgers, S. Sharpe, P. Capewell, Willie Weir, B. Bradley, David Sutton. 7 April 2014. Trypanosomosis in working equids in West Africa: characterising neurological disease. Presented at British Society for Parasitology Spring Meeting. (7 April 2014).

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Date presented: 
Monday 7 April 2014
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Viraemic frequencies and seroprevalence of non-primate hepacivirus and equine pegiviruses in horses and other mammalian species

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Sinead Lyons, Amit Kapoor, Bradley Schneider, Nathan Wolfe, Geoff Culshaw, Brendan Corcoran, Andy Durham, Faith A. Burden, Bruce McGorum, Peter Simmonds. September 2014. Viraemic frequencies and seroprevalence of non-primate hepacivirus and equine pegiviruses in horses and other mammalian species. Journal of General Virology.

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Publication date: 
5 September 2014
DOI number: 
10.1099/vir.0.065094-0
Abstract

Non-primate hepacivirus (NPHV), equine pegivirus (EPgV) and Theiler's disease associated virus (TDAV) are newly discovered members of two genera in the Flaviviridae family, Hepacivirus and Pegivirus respectively, that include human hepatitis C virus (HCV) and human pegivirus (HPgV). To investigate their epidemiology, persistence and clinical features of infection, large cohorts of horses and other mammalian species were screened for NPHV, EPgV and TDAV viraemia and for past exposure through serological assays for NPHV and EPgV-specific antibodies. NPHV antibodies were detected in 43% of 328 horses screened for antibodies to NS3 and core antibodies, of which three were viraemic by PCR. All five horses that were stablemates of a viraemic horse were seropositive, as was a dog on the same farm. With this single exception, all other species were negative for NPHV antibodies and viraemia (donkeys (n=100), dogs (n=112), cats (n=131), non-human primates (n=164) and humans (n=362). EPgV antibodies to NS3 were detected in 66.5% of horses, including 11 of the 12 horses that had EPgV viraemia. All donkey samples were negative for EPgV antibody and RNA. All horse and donkey samples were negative for TDAV RNA. By comparing viraemia frequencies in horses with and without liver disease, no evidence was obtained that supported an association between active NPHV and EPgV infections with hepatopathy. The study demonstrates that NPHV and EPgV infections are widespread and enzootic in the study horse population and confirms that NPHV and potentially EPgV have higher frequencies of viral clearance than HCV and HPgV infections in humans.

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Review of Physiological Differences Between Donkeys and Horses

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Karen Rickards. 8 November 2014. Review of Physiological Differences Between Donkeys and Horses. Presented at Donkey Welfare Symposium 2014. (7 November - 9 November 2014). California, USA.

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Date presented: 
Saturday 8 November 2014

Review: Pharmacology and therapeutics in donkeys

Citation

D. A. Grosenbaugh, C. R. Reinemeyer, D. Figueiredo. October 2011. Review: Pharmacology and therapeutics in donkeys. Equine Veterinary Education. 23:10. 523-530.

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Publication date: 
1 October 2011
Volume: 
23
Issue: 
10
Page numbers: 
523-530
DOI number: 
10.1111/j.2042-3292.2011.00291.x
Abstract

Therapeutics are often administered to donkeys based on dosage and intervals recommended for horses because very few drugs have donkey-specific label indications. Yet differences between donkeys and horses in drug distribution, metabolism and elimination have been noted for most therapeutic agents studied. These differences can be partially explained by the donkey's unique physiology. Since their ancestors evolved in a desert environment, the modern donkey exhibits qualities that allow them to tolerate dehydration better than the horse and recover more quickly from its effects. Fluid balance and body water compartment partitioning differ from the horse and may have implications regarding drug distribution. Since donkeys are preferential browsers, differences in diet may have influenced evolutionary differences in metabolic disposition of drugs. It is important to acknowledge these differences when designing dose regimes for donkeys based on horse protocols in order to avoid either lack of efficacy or toxicity.

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Expression of PGP 9.5 by Enteric Neurons in Horses and Donkeys with and without Intestinal Disease

Citation

Neil Hudson, G.T. Pearson, I.G. Mayhew, Christopher Proudman, Faith A. Burden, Constance Fintl. November 2013. Expression of PGP 9.5 by Enteric Neurons in Horses and Donkeys with and without Intestinal Disease. Journal of Comparative Pathology.

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Publication date: 
26 November 2013
DOI number: 
doi.org/10.1016/j.jcpa.2013.11.203
Abstract

Intestinal motility disorders are an important problem in horses and donkeys and this study was carried out in order to evaluate the enteric neurons in animals with and without intestinal disease. Surplus intestinal tissue samples were collected from 28 horses undergoing exploratory laparotomy for colic. In addition, surplus intestinal samples from 17 control horses were collected immediately following humane destruction for clinical conditions not relating to the intestinal tract. Similar samples were also collected during routine post-mortem examinations from 12 aged donkeys; six animals were humanely destroyed for conditions related to the intestinal tract, while the remaining six were humanely destroyed for other reasons including dental and orthopaedic diseases. Tissue samples were fixed in formalin and immunohistochemical labelling was performed targeting the enteric neurons using a polyclonal antibody specific for the neuronal marker PGP 9.5. The distribution and density of neuronal networks were assessed qualitatively and semiquantitatively. There was strong PGP 9.5 expression in both the horse and donkey samples and labelling was detected throughout the tissue sections. In both species, PGP 9.5-immunoreactive nerve fibres were detected in all layers of the intestinal tract, both in large and small intestinal samples. Networks of enteric neurons were present in the donkey with a similar distribution to that seen in the horse. There was no demonstrable difference in enteric neuronal density and distribution in the groups of animals with intestinal disease compared with those without, apart from two (out of 28) horses with intestinal disease that showed a marked reduction in PGP 9.5 immunoreactivity. Apart from these two animals, this total cohort analysis differs from some previously observed findings in horses with intestinal disease and may therefore reflect the different pathophysiological processes occurring in varying intestinal conditions resulting in colic both in the donkey and the horse.

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Spatial cognition and perseveration by horses, donkeys and mules in a simple A-not-B detour task

Citation

Britta Osthaus, Leanne Proops, Ian Hocking, Faith A. Burden. December 2012. Spatial cognition and perseveration by horses, donkeys and mules in a simple A-not-B detour task. Animal Cognition.

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Publication date: 
28 December 2012
Journal: 
Animal Cognition
DOI number: 
DOI 10.1007/s10071-012-0589-4
Abstract

We investigated perseveration and detour behaviour in 36 equids (Equus caballus, E. asinus, E. caballus x E. asinus) and compared these data to those of a previous study on domestic dogs (Canis familiaris). The animals were required to make a detour through a gap at one end of a straight barrier in order to reach a visible target. After one, two, three or four repeats (A trials), the gap was moved to the opposite end of the barrier (B trials). We recorded initial deviations from the correct solution
path and the latency to crossing the barrier. In the A trials, mules crossed the barrier significantly faster than their parental species, the horses and donkeys. In the B trials, following the change of gap location, all species showed a reduction in performance. Both dogs and horses exhibited significant spatial perseveration, going initially to the previous gap location. Donkeys and mules, however, performed at chance level. Our results suggest that hybrid vigour in mules extends to spatial abilities.

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Mind the gap: Spatial perseveration by horses, donkeys and mules in a simple detour task

Citation

Britta Osthaus, Faith A. Burden, Ian Hocking, Leanne Proops. 28 June 2012. Mind the gap: Spatial perseveration by horses, donkeys and mules in a simple detour task. Presented at ASAB Interdisciplinary Workshop: Physical Cognition and Problem Solving. (27 June - 28 June 2012). Birmingham, UK.

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Date presented: 
Thursday 28 June 2012
Abstract

We compared spatial problem solving abilities in the mule (Equus asinus x Equus caballus) with that of its parent species to assess the effects of hybridization on cognition. In a detour task the animals(N=48) were required to make a detour through a gap at one end of a straight barrier in order to reach a visible target. After one, two, three or four repeats (A trials), the gap was moved to the opposite end of the barrier (B trials) and deviations from the straight line and the latency to crossing the barrier were recorded. Mules performed significantly above chance level on their first detour, unlike the other two species. We discuss our results with reference to hybrid vigour and to the flexibility of problem solving strategies with regards to species differences.

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