welfare

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

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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.

A clinical survey on the prevalence and types of cheek teeth disorders present in 400 Zamorano-Leonés and 400 Mirandês donkeys (Equus asinus)

Citation

J. B. Rodrigues, Padraic M. Dixon, E. Bastos, F. San Roman, C. Viegas. November 2013. A clinical survey on the prevalence and types of cheek teeth disorders present in 400 Zamorano-Leonés and 400 Mirandês donkeys (Equus asinus). Veterinary Record. 173:23. 581.

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Publication date: 
4 November 2013
Journal: 
Veterinary Record
Volume: 
173
Issue: 
23
Page numbers: 
581
Abstract

Dental disease is now recognised as a major but often unrecognised disorder of equids, including horses and donkeys. However, very few large clinical studies have documented the prevalence and type of dental disease present in different equid populations and no dental studies have been reported in Zamorano-Leonés or Mirandês donkeys, two endangered donkey breeds. Clinical and detailed oral examinations were performed in 400 Mirandês and 400 Zamorano-Leonés donkeys in Portugal and Spain. It was found that just 4.5 per cent had ever received any previous dental care. Cheek teeth (CT) disorders were present in 82.8 per cent of these donkeys, ranging from a prevalence of 29.6 per cent in the <2.5-year-old group to 100 per cent in the >25-year-old group. These CT disorders included enamel overgrowths (73.1 per cent prevalence but with just 6.3 per cent having associated soft tissue injuries), focal overgrowths (37.3 per cent), periodontal disease (23.5 per cent) and diastemata (19.9 per cent). Peripheral caries was present in 5.9 per cent of cases, but inexplicably, infundibular caries was very rare (1.3 per cent prevalence); this may have been due to their almost fully foraged diet. The high prevalence of enamel overgrowths in these donkeys, most which never received concentrates, also raises questions about the aetiology of this disorder. This very high prevalence of CT disorders, especially in older donkeys, was of great welfare concern in some cases and emphasises the need for routine dental care in these cases on welfare grounds and in order to help preserve these unique breeds.

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Working across Europe to improve donkey welfare

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Alexandra K. Thiemann, Andy Foxcroft. August 2016. Working across Europe to improve donkey welfare. The Veterinary Record. 1796. 298-300.

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Publication date: 
19 August 2016
Volume: 
1796
Page numbers: 
298-300
DOI number: 
10.1136/vr.i4112
Abstract

The UK public and veterinary profession often think of the equine charity sector as dealing with issues directly related to the UK equine population – overproduction, rehoming, shelter and welfare. However, the Donkey Sanctuary, like many UK-based equine charities, also works in Europe and further afield to try to address a much broader range of issues, as Alex Thiemann and Andy Foxcroft explain

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The prevalence of lameness and associated risk factors in cart mules in Bahir Dar, Ethiopia

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Alina Ali, Solomon Orion, Tewodros Tesfaye, Jennifer A. Zambriski. September 2016. The prevalence of lameness and associated risk factors in cart mules in Bahir Dar, Ethiopia. Tropical Animal Health and Production.

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Publication date: 
1 September 2016
DOI number: 
10.1007/s11250-016-1121-7
Abstract

Ethiopia has 7.1 million donkeys and mules, the majority of which are used as pack animals. Factors such as poor harness quality, long-distance traveling, and heavy cartloads have been linked to reduced work efficiency. Addressing the health and welfare of working equids is imperative not only for the animals but also for the households dependent upon them for livelihood. In developing countries, 75 % of working equids have gait or limb abnormalities, but the relationship between workload and prevalence of lameness is unknown. We examined 450 cart mules in Bahir Dar,
Ethiopia. Lameness and workload were assessed through use of a survey and lameness exam. We found that 26.8 % of cart mules were lame, and acute lameness of the forelimb was the most common. Animals with poor harness quality were 2.5 times more likely to have sores and 1.6 times more likely to be lame. Lameness tended to be associated with cartloads >700 kg (P = 0.09), and there was a significant association
between multiple-leg lameness and cartload weight (P = 0.03). The presence of sores was the best predictor of lameness (P = 0.001). Possible areas of intervention may include education to reduce average daily workload and improving harness design.

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