United Kingdom

Clinical evaluation and preventative care in donkeys should follow similar guidelines as for horses. There are species-specific differences due to the desert-adapted physiology of the donkey. Donkeys are mainly used as pack animals, companions and for production of meat or milk - they may be kept well into old age. Diseases often present late or may go unrecognized leading to poor welfare and quality of life. Basic knowledge of nutrition, blood values, pharmacology and common disease recognition will help veterinarians improve the health and welfare of donkeys.

Published online ahead of print.

Dental disorders have a high prevalence in older donkeys and horses, but the nature and pathogenesis of many of these disorders have yet to be established.

Objectives

The identification and determination of the prevalence of important dental disorders in different age groups in a large single population of donkeys, to establish a better understanding of the nature and pathogenesis of these disorders.

Methods

A prospective cross-sectional study was performed on the donkey population at The Donkey Sanctuary with detailed oral examinations of 357 donkeys within 7 different age groups (age range 2-53 years) recorded.

Results

The prevalence of dental disease in all donkeys was 73%, increasing in prevalence from 28% in the youngest to 98% in the oldest age group. There was an increase in prevalence of commonly recognised dental disorders with increasing age, such as: diastemata (3.8% in youngest to 86% in oldest group); missing teeth (0-56%); overgrown teeth (15-86%); worn teeth (8-84%); displaced teeth (0-38%); and periodontal disease (0-28%).

Conclusions

There was a significant increase in the prevalence of dental disorders with increasing age with the largest significant increase for most dental disorders occurring in the 15-20 year age group.

Potential significance

Most dental disorders significantly increase in prevalence in the 15-20 year age group and, therefore, prophylactic geriatric dental treatment in donkeys should be commenced from age 15 years.

Dental disease has been shown to be a risk factor for weight loss and colic in horses. No extensive clinical studies in donkeys have investigated the potential relationship between different dental disorders, or between dental disease and systemic disorders.

Objectives

To determine possible associations between dental disease and body condition score, weight loss, the need for supplemental feeding and prevalence of colic in donkeys of all ages, and to gain a better understanding of the pathogenesis of dental disease by the determination of associations between different dental disorders.

Methods

A prospective cross-sectional analysis of clinical dental examinations of 357 donkeys in The Donkey Sanctuary, Sidmouth was performed. Other epidemiological factors such as estimated age group, body condition score, weight loss, medical history and supplemental feeding were also recorded, and multiple regression analyses were performed to determine possible associations.

Results

Donkeys from older age groups were more likely to have dental disease, poor body condition score and suffered previous colic episodes. The presence of dental disease was also significantly associated with weight loss, colic, low body condition score and the need for supplemental feeding. The presence of diastemata, periodontal disease, wave mouth, smooth mouth and step mouth are frequently associated with the presence of other dental disorders.

Conclusions

In addition to oral-related pain, dental disease can cause significant systemic disorders and so has increased welfare implications in donkeys. Some dental disorders promote the development of other types of dental abnormalities and thus increase the severity of dental disease in individual animals.

Potential significance

Effective treatment of dental disorders slows down the progression of dental disease and decreases the risk of developing some medical disorders such as colic and weight loss that are associated with dental disease.

Donkey Pulmonary Fibrosis (DPF) is a spontaneous syndrome of aged donkeys with high prevalence (35%). No previous detailed characterisation of DPF has been performed. We sought to determine the similarities of DPF to recognised patterns of human pulmonary fibrosis.

Whole lungs were collected from 32 aged donkeys at routine necropsy. Gross examination revealed pulmonary fibrosis in 19 donkeys (DPF cases), while 13 (controls) had grossly normal lungs. Eighteen whole inflated ex vivo lungs (11 DPF, 7 controls) were imaged with high resolution computed tomography (HRCT), while the remainder were sectioned and photographed. Tissue samples were collected from all lungs for histopathological evaluation using a standardised protocol. HRCT images and histology sections were reviewed independently and blindly. Lung tissue was analysed for herpes virus, fungal hyphae, mycobacteria and dust content.

Ten of 19 DPF lungs were categorised as being 'consistent with' pleuroparenchymal fibroelastosis (PPFE) according to previously defined histological and imaging criteria. All 10 PPFE-like lungs had marked pleural and subpleural fibrosis, predominantly within the upper lung zone, with accompanying intra-alveolar fibrosis and elastosis. Asinine herpesvirus (AsHV) was ubiquitously expressed within control and DPF lung tissue. No other aetiological agents were identified.

Many cases of DPF share key pathological and imaging features with human PPFE, a rare interstitial pneumonia. Consequently, further study of DPF may help elucidate the aetiopathogenesis of human PPFE.

Impaction colic is the single most common type of colic diagnosed in a large population of donkeys (more than 2000 animals) at The Donkey Sanctuary, UK and the fatality rate from the disease is high. Here we identify risk factors for impaction colic in this population during 2006 using an unmatched case control study. There were 71 cases of impaction colic and multivariable analysis identified a number of variables associated with the disease. Management factors that increased the risk of impaction included paper bedding, feeding of concentrates, limited access to pasture and increasing number of carers. In addition health variables that were associated with an increased risk of impaction colic were weight loss, recent vaccination and a number of dental abnormalities. This study has identified variables which may help to identify donkeys at high risk of impaction colic; those with a history of weight loss and with concurrent dental pathology. Furthermore the study has also identified a number of variables that may be targeted to reduce the incidence of impaction colic in this donkey population, such as modification of concentrate feeding practices and pasture access.

The temperament of individual donkeys being sent to foster homes from The Donkey Sanctuary was evaluated with a calibrated-line rating method using eight pairs of contrary adjectives to describe traits, e.g. calm-nervous. The donkeys' attitude to other animals and people was also recorded. A factor analysis of normalized scores for the trait adjective pairs produced two factors: 'obduracy' and 'vivacity'. Once in their foster homes, the donkeys appeared more overtly outgoing. One explanation of this change in temperament is that pairs of donkeys in foster homes experience less social intimidation than those living in groups. The donkeys' attitude towards other donkeys and people was unaffected by their change in surroundings, but their behaviour towards other animals could change. Temperament assessment can assist in matching potential pets with homes, e.g. donkeys that were perceived as liking humans had a higher 'vivacity' score and donkeys that were reported to like dogs, had a lower 'obduracy' score.

The Donkey Sanctuary (DS) owns 3500–4000 donkeys, estimated to be about 35 per cent of the UK population. Although postmortem surveys suggest a high prevalence of cardiovascular disease in donkeys, there is sparse clinical information about cardiovascular examination findings and echocardiographic findings in health and disease. In this cross-sectional study, auscultation findings were recorded, and in a subset of donkeys, echocardiography was used to screen for structural and functional cardiac disease. 202 donkeys were examined; 117 geldings and 85 females. Heart sounds S1 and S2 were detected in all donkeys, but none had audible S3. S4 was detected in nine (4.5 per cent; significantly older than those without S4; P<0.001). A heart murmur was detected in four donkeys. Echocardiography identified these to be due to a ventricular septal defect in one, and aortic regurgitation in three. An additional 43 donkeys had echocardiography. A further 10 donkeys were identified to have aortic insufficiency, but no other valvular regurgitation. 76/202 donkeys subsequently underwent postmortem examination. Three showed degenerative aortic valve changes. One donkey had nodular lesions in the intima of proximal aorta and sinus of Valsalva. Histopathology showed multifocal chronic nodular eosinophilic arteritis, consistent with verminous arteritis. The Donkey Sanctuary pathology database identified other similar cases.

The role of donkeys in the UK and Europe has changed over the past 40 years, and is still changing – these equids are primarily used as companions, but also for tourism, therapy and increasingly for milk production. When it comes to the end of their lives and issues surrounding equine end-of-life care, a recent study highlighted that many donkey owners rely on their vet to provide them with information on quality of life (QOL) assessment, geriatric care and euthanasia planning. This article aims to assist veterinary surgeons in assessing donkey welfare and helping owners decide how to improve QOL or whether an end-point has been reached and euthanasia is indicated.

A field study was designed to investigate the re-establishment of patent lungworm infections in donkeys following an anthelmintic treatment regime which was effective against Dictyocaulus arnfieldi. In April 1979 faecal samples from 259 donkeys were examined and each animal classified as a negative, low positive or high positive excretor of lungworm larvae. During the summer the control group of 126 donkeys showed an increase in the number of excretors from 80 per cent in April to 91 per cent in October. At the same time there was a rise in the faecal larval output of individual animals so that by October 59 per cent were classified as high positive compared with only 20 per cent in April. The treated group of 133 donkeys received 3.5 g mebendazole daily for 5 days during April and as a result the number of excretors fell from 66 per cent pretreatment to 23 per cent one month after treatment. Despite exposure to infected pastures throughout the summer this figure was maintained at a comparatively low level and by October patent infections had been re-established in only 15 per cent of the donkeys that were negative after treatment.

Cyathostomins are the most important gastrointestinal nematode infecting equids. Their effective control is currently under threat due to widespread resistance to the broad spectrum anthelmintics licenced for use in equids. In response to similar resistance issues in other helminths, there has been increasing interest in alternative control strategies, such as bioactive plant compounds derived from traditional ethnoveterinary treatments. This study used an evidence-based approach to evaluate the potential use of plant extracts from the UK and Ethiopia to treat cyathostomins. Plants were shortlisted based on findings from a literature review and additionally, in Ethiopia, the results of a participatory rural appraisal (PRA) in the Oromia region of the country. Systematic selection criteria were applied to both groups to identify five Ethiopian and four UK plants for in vitro screening. These included Acacia nilotica (L.) Delile, Cucumis prophetarum L., Rumex abyssinicus Jacq., Vernonia amygdalina Delile. and Withania somnifera (L.) Dunal from Ethiopia and Allium sativum L. (garlic), Artemisia absinthium L., Chenopodium album L. and Zingiber officinale Roscoe. (ginger) from the UK. Plant material was collected, dried and milled prior to hydro-alcoholic extraction. Crude extracts were dissolved in distilled water (dH2O) and dimethyl sulfoxide (DMSO), serially diluted and screened for anthelmintic activity in the larval migration inhibition test (LMIT) and the egg hatch test (EHT). Repeated measures ANOVA was used to identify extracts that had a significant effect on larval migration and/or egg hatch, compared to non-treated controls. The median effective concentration (EC-50) for each extract was calculated using PROBIT analysis. Of the Ethiopian extracts A. nilotica, R. abyssinicus and C. prophetarum showed significant anthelmintic activity. Their lowest EC-50 values were 0.18 (Confidence interval (CI): 0.1-0.3), 1.1 (CI: 0.2-2.2) and 1.1 (CI: 0.9-1.4) mg/ml, respectively. All four UK extracts, A. sativum, C. album, Z. officinale and A. absinthium, showed significant anthelmintic activity. Their lowest EC-50 values were 1.1 (CI: 0.9-1.3), 2.3 (CI: 1.9-2.7) and 0.3 (CI: 0.2-0.4) mg/ml, respectively. Extract of A. absinthium had a relatively low efficacy and the data did not accurately fit a PROBIT model for the dose response relationship, thus an EC-50 value was not calculated. Differences in efficacy for each extract were noted, dependent on the assay and solvent used, highlighting the need for a systematic approach to the evaluation of bioactive plant compounds. This study has identified bioactive plant extracts from the UK and Ethiopia which have potential as anthelmintic forages or feed supplements in equids.