United Kingdom

In this paper, the management and health problems of donkeys on loan to independent carers from The Donkey Sanctuary are characterised, and the demographics of the UK's donkey population are described using data from a variety of sources. All carers that fostered a donkey from The Donkey Sanctuary between September 2004 and August 2005 (1432 donkeys) were surveyed using a postal questionnaire requesting information about the donkey, its premises, daily care, health and preventive medicine. The response rate was 77.8 percent. The mean (sd) age of the donkeys was 20.8 (7.4) years. The majority (92 percent) of the donkeys were kept as pets. Approximately one-third (33.6 percent) of the donkeys were overweight. The most common medical problems were hoof, dermal and oral problems. A total of 86 percent of the donkeys had a dental examination at least every 12 months, and at least 45 percent had at least one dental problem.

Infestations by lice can be a significant clinical and welfare issue in the management of large animals. The limited range of commercial pediculicides available and the development of resistance have led to the need to explore alternative louse management approaches. The results of in vitro and in vivo trials undertaken to control populations of the donkey chewing louse, Bovicola ocellatus (Piaget) (Phthiraptera: Trichodectidae) using the essential oils of tea tree (Melaleuca alternifolia) and lavender (Lavandula angustifolia) are reported here. Results of contact and vapour bioassays showed that 5% (v/v) tea tree and lavender oils resulted in > 80% louse mortality after 2 h of exposure. On farms, separate groups of 10 donkeys sprayed with 5% (v/v) tea tree and lavender oil as part of their usual grooming regime showed significant reductions in louse numbers compared with a control group (0.2% polysorbate 80 in water). These findings indicate that tea tree and lavender essential oils can provide clinically useful levels of control of B. ocellatus when used as part of a grooming routine and suggest that with further development could form the basis of an easy to apply and valuable component of a louse management programme for donkeys

Roundworms and flatworms that affect donkeys can cause disease. All common helminth parasites that affect horses also infect donkeys, so animals that co-graze can act as a source of infection for either species. Of the gastrointestinal nematodes, those belonging to the cyathostomin (small strongyle) group are the most problematic in UK donkeys. Most grazing animals are exposed to these parasites and some animals will be infected all of their lives. Control is threatened by anthelmintic resistance: resistance to all 3 available anthelmintic classes has now been recorded in UK donkeys. The lungworm, Dictyocaulus arnfieldi, is also problematical, particularly when donkeys co-graze with horses. Mature horses are not permissive hosts to the full life cycle of this parasite, but develop clinical signs on infection. In contrast, donkeys are permissive hosts without displaying overt clinical signs and act as a source of infection to co-grazing horses. Donkeys are also susceptible to the fluke, Fasciola hepatica. This flatworm can be transmitted, via snails and the environment, from ruminants. As with cyathostomins, anthelmintic resistance is increasing in fluke populations in the UK. A number of the anthelmintic products available for horses do not have a licence for use in donkeys, and this complicates the design of parasite control programmes. As no new equine anthelmintic classes appear to be near market, it is important that the efficacy of currently effective drugs is maintained. It is important that strategies are used that attempt to preserve anthelmintic efficacy. These strategies should be based on the concept that the proportion of worms in a population not exposed to anthelmintic at each treatment act as a source of ‘refugia’. The latter is an important factor in the rate at which resistance develops. Thus, it is imperative that parasite control programmes take into account the need to balance therapy to control helminth-associated disease with the requirement to preserve anthelmintic effectiveness.

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.