United Kingdom

Ten normal cheek teeth (CT) were extracted at post mortem from donkeys that died or were euthanased for humane reasons. Decalcified histology was performed on three sections (sub-occlusal, mid-tooth and pre-apical) of each tooth, and undecalcified histology undertaken on sub-occlusal sections of the same teeth. The normal histological anatomy of primary, regular and irregular secondary dentine was found to be similar to that of the horse, with no tertiary dentine present. Undecalcified histology demonstrated the normal enamel histology, including the presence of enamel spindles. Scanning electron microscopy was performed on mid-tooth sections of five maxillary CT, five mandibular CT and two incisors. The ultrastructural anatomy of primary and secondary dentine, and equine enamel types-1, -2 and -3 (as described in horses) were identified in donkey teeth. Histological and ultrastructural donkey dental anatomy was found to be very similar to equine dental anatomy with only a few quantitative differences observed.

Post-mortem examination of 19 donkey skulls showed that donkeys have a greater degree of anisognathia (27% width difference between upper and lower jaws) compared to horses (23%). Teeth (n = 108) were collected from 14 skulls and examined grossly and by computed axial tomography (CAT). A greater degree of peripheral enamel infolding was found in mandibular cheek teeth (CT) compared to maxillary CT (P < 0.001). A significant increase in peripheral cementum from the apical region to the clinical crown was demonstrated in all CT (P < 0.0001). All donkey CT had at least five pulp cavities with six pulp cavities present in the 06s and 11s. A new endodontic numbering system for equid CT has been proposed. A greater occlusal depth of secondary dentine (mm) was present in older donkeys (>16 years) than in the younger (<15 years) donkeys studied. Based on gross and CAT examinations, donkey dental anatomy was shown to be largely similar to that described in horses.

The donkey's evolution, ethology and learning capacity mean that the behaviour of donkeys and mules is significantly different to that of the horse. Subtle behaviour change in the donkey can indicate severe, life-threatening disease. An understanding of donkey and mule behaviour will help veterinary surgeons to handle these animals safely, treat them effectively and educate owners to spot the subtle signs of disease

Equine cheek teeth (CT) diastemata often cause deep periodontal food pocketing and are therefore regarded as a painful dental disorder of equidae. However there appears to be no information available on the size or shape of these diastemata. This post mortem study examined 16 donkey skulls (mean age = 32-years) containing 45 CT diastemata to define the anatomical shape and dimensions of these diastemata, and of the associated periodontal food pockets that occur with this disorder. Diastemata were found to more commonly involve mandibular (56.0%) compared with maxillary CT (44.0%), and 71.0% of these diastemata had adjacent intercurrent dental disorders that may have predisposed donkeys to the diastemata. The median widths of all diastemata were 2.0-mm at the occlusal surface and 3.1-mm at the gingival margin, with no diferences in widths between the lateral or medial aspects of diastemata. Diastemata were defined as open (60.00%) or valve (40.00%) based on their gross appearance. This classification was confirmed to be accurate by measurements that showed valve diastemata to have an occlusal to gingival width ratio of 0.4, in contrast to open diastemata where this ratio was 1.07. Food was impacted in 89.0% of diastemata, but all diastemata had adjacent periodontal disease. Periodontal food pocketing was present adjacent to 76.0% of diastemata, more commonly on the lateral aspect (73.0% prevalence; mean pocket depth = 4.1-mm) than the medial aspect (47.0% prevalence; mean pocket depth = 2.4-mm). The depth of periodontal pockets of diastemata was not associated with the height of the erupted crowns of adjacent CT.

Cyathostomins are the most prevalent parasitic pathogens of equids worldwide. These nematodes have been controlled using broad-spectrum anthelmintics; however, cyathostomin resistance to each anthelmintic class has been reported and populations insensitive to more than one class are relatively commonplace. The faecal egg count reduction test (FECRT) is considered the most suitable method for screening anthelmintic sensitivity in horses, but is subject to variation and is relatively time-consuming to perform. Here, we describe a larval migration inhibition test (LMIT) to assess ivermectin (IVM) sensitivity in cyathostomin populations. This test measures the paralysing effect of IVM on the ability of third stage larvae (L3) to migrate through a pore mesh. When L3 from a single faecal sample were examined on multiple occasions, variation in migration was observed: this was associated with the length of time that the L3 had been stored before testing but the association was not significant. Half maximal effective concentration (EC50) values were then obtained for cyathostomin L3 from six populations of horses or donkeys that showed varying sensitivity to IVM in previous FECRTs. Larvae from populations indicated as IVM resistant by FECRT displayed significantly higher EC50 values in the LMIT than L3 from populations classified as IVM sensitive or L3 from populations that had not been previously exposed to IVM or had limited prior exposure. The analysis also showed that EC50 values obtained using L3 from animals in which IVM faecal egg count reduction (FECR) levels had been recorded as <95% were significantly higher than EC50 values obtained using L3 from animals for which FECR was measured as >95%. For one of the populations, time that had elapsed since IVM administration had an effect on the EC50 value obtained, with a longer time since treatment associated with lower EC50 values. These results indicate that the LMIT has value in discriminating IVM sensitivity amongst cyathostomin populations, but several factors were identified that need to be taken into account when executing the test and interpreting the derived data.

Objective

To establish and validate an objective method of radiographic diagnosis of anatomic changes in laminitic forefeet of donkeys on the basis of data from a comprehensive series of radiographic measurements.

Animals

85 donkeys with and 85 without forelimb laminitis for baseline data determination; a cohort of 44 donkeys with and 18 without forelimb laminitis was used for validation analyses.

Procedures

For each donkey, lateromedial radiographic views of 1 weight-bearing forelimb were obtained; images from 11 laminitic and 2 nonlaminitic donkeys were excluded (motion artifact) from baseline data determination. Data from an a priori selection of 19 measurements of anatomic features of laminitic and nonlaminitic donkey feet were analyzed by use of a novel application of multivariate statistical techniques. The resultant diagnostic models were validated in a blinded manner with data from the separate cohort of laminitic and nonlaminitic donkeys.

Results

Data were modeled, and robust statistical rules were established for the diagnosis of anatomic changes within laminitic donkey forefeet. Component 1 scores ≤ −3.5 were indicative of extreme anatomic change, and scores from −2.0 to 0.0 denoted modest change. Nonlaminitic donkeys with a score from 0.5 to 1.0 should be considered as at risk for laminitis.

Conclusions and clinical relevance

Results indicated that the radiographic procedures evaluated can be used for the identification, assessment, and monitoring of anatomic changes associated with laminitis. Screening assessments by use of this method may enable early detection of mild anatomic change and identification of at-risk donkeys.

Background

In the UK, there are thousands of donkeys being cared for by charities; however, little is known about the reasons for relinquishment or their previous health status, with even less information available in published literature. Such information could help to identify factors contributing to poor equine welfare and guide the development of appropriate educational resources.

Objectives

To describe the characteristics of the relinquished donkeys and to better understand the current preventative healthcare status of donkeys relinquished into The Donkey Sanctuary.

Study design

Cross‐sectional observational survey.

Methods

A total of 596 donkeys were admitted during a 30‐month period. Each had a health check at arrival; and previous management information was provided by the owner. Data were retrieved from The Donkey Sanctuary database, inputted into a specific Microsoft Access 2016 database then exported for analysis in IBM SPSS 19.0 for Windows®. Mules and ponies were excluded from the study.

Results

Many donkeys arrived without a valid passport (32.3%) or microchip (49.7%). Only 23.2% were fully protected against influenza and tetanus and 21.0% of the donkeys had no previous anthelmintic treatment history. Geriatric donkeys often suffered from moderate to severe dental disease in need of advanced treatment, and 43.9% had received no dental treatment within the last year. Overall 26.3% of donkeys were classed as overweight and 8.6% were obese. The median time since the last hoof trim was 10 weeks.

Main limitation

The health status of the studied donkeys may have been affected by the reasons for relinquishment, and associations require further investigation.

Conclusions

This study highlights the need for improving preventative healthcare in donkeys to ensure better welfare within the population.

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.