donkey

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

Background

Factors affecting working equid welfare are wide-ranging and reflect cultural, economic and climatic conditions, the type of work equids are used for, and individual differences in the practices of their handlers. In Mexico working equids are widely used for facilitating agricultural activities, however, welfare issues are common.

Objectives

To assess working equids across three communities in Mexico, identify predominant welfare problems and document how these problems vary across locations and associated working roles and species type.

Study design

Cross-sectional survey.

Methods

The study combined the administration of a wide-ranging questionnaire to equid handlers/owners and a welfare assessment of their animal. 120 equid owners were asked about their equid management practices, the working conditions and health status of their animal. The welfare of their equids (56 donkeys, 7 mules, 57 horses) was assessed by evaluating body condition, signs of illness or injury, and behavioural indicators.

Results

Welfare varied by species, working role, sex and location. The poorest welfare was seen in one of the two arid regions (the third location having a tropical climate). Donkeys had poorer welfare than horses, and equids used for packing had poorer welfare than those used for riding and agroforestry. Overall poor body condition and wounds were the most common problems seen.

Main limitations

Work type, species type and location strongly co-varied, thus the impact of each factor could not be assessed in isolation. The sample size was relatively small.

Conclusions

Results showed significant regional variations in welfare, suggesting that environmental and/or cultural variations are producing a major effect on welfare.

Published online ahead of print.

The microhardness of the enamel, primary dentine and regular secondary dentine of seven donkey and six horse incisors was determined with a Knoop indenter at the subocclusal and mid-tooth level. The mean microhardnesses of the donkey incisor enamel, primary dentine and secondary dentine were 264·6 63·00 and 53·6 Knoop Hardness Number, respectively. There was no significant difference between the microhardness of the enamel and primary dentine on the incisors of the donkeys and horses, but the microhardness of the regular secondary dentine of the donkeys' incisors at the mid-tooth level was slightly but significantly less than that of the horses. There was also a difference in the microhardness of the secondary dentine between the subocclusal and mid-tooth levels in both donkey and horse incisors.

Because most donkeys live well beyond 30 years of age (Crane 1997), it has been proposed that their teeth may be harder than the teeth of horses, wear more slowly, and thus remain functional for longer (Misk and Seilem 1999). There have been studies of dental microhardness in human beings (Craig and Peyton 1958, Collys and others 1992), sheep (Suckling 1979), cattle (Attin and others 1997) and horses (Muylle and others 1999b). In horses, there are differences between breeds in the rate of dental wear caused by attrition (Muylle and others 1997, 1998) and in the microhardness of enamel and secondary dentine (Muylle and others 1999b), which could account for these differences. It is proposed that there may be a similar difference between the microhardness of the teeth of donkeys and horses that may contribute to the less rapid attrition of donkey teeth.

The aim of this study was to compare the microhardness of the enamel and primary and secondary dentine of the incisor teeth of donkeys and horses, to determine whether there was a significant difference between them.

Normal dental anatomy and the range of dental disorders found in donkeys are largely similar to those described in horses. Recent studies have shown dental disease to have a high prevalence in donkeys. Some dental disorders, such as diastemata, displaced teeth and wave mouth can have serious clinical consequences by causing oral pain and weight loss and even predispose to colic. Many of these signs can be prevented by regular dental treatment that can slow down or even prevent the progression of these disorders.

Clinical dental examinations of 203 unsedated working donkeys in tropical and temperate climatic areas in Mexico revealed a high prevalence (62%) of dental disease with sharp enamel points present in 98% of the animals. More significant dental disorders (diastemata, 4%; overgrown teeth, 18%; worn teeth, 16%; missing teeth, 0.5%; displaced teeth, 1.5%; fractured teeth, 2%) with welfare implications that required immediate treatment were also present in 18% of donkeys. The high prevalence of buccal ulcers (14.3%) and calluses (13.3%) present in this population was believed to be due to the high prevalence of sharp enamel points in conjunction with the use of tight nose bands and head collars. Dental disease was significantly associated with age groups, but not with body condition score or to the climatic area where the donkeys lived. As part of more general examinations, 81% of donkeys that had faecal egg counts performed, had parasite burdens which mainly showed a moderate level of infection. This study concluded that dental disease is a welfare concern in working donkeys in Mexico.

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.

Donkeys maintain a special status in the minds of the UK animal-owning population in that, although they are physically large animals, they are usually regarded by their owners as companion animals in the same vein as dogs and cats. This dichotomy can bring about clinical challenges rarely seen with other species. Although most conditions affecting donkeys are similar to those occurring in horses, donkeys by their very nature can behave differently in the face of disease. Hence, some clinical presentations that would ordinarily be dismissed in other equids must be considered as medical/surgical emergencies in the donkey. This article, the first in an occasional series discussing the clinical approach to problems in the donkey, describes the options for castration, and offers practical advice on how to avoid some common pitfalls and potentially fatal complications that are specific to this species.

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.