United Kingdom

Essential oils in the management of the donkey louse, Bovicola ocellatus

Citation

Lauren Ellse, Bryony Sands, Faith A. Burden, Richard Wall. March 2015. Essential oils in the management of the donkey louse, Bovicola ocellatus. Equine Veterinary Journal.

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Publication details
Publication date: 
10 March 2015
DOI number: 
DOI: 10.1111/evj.12431
Abstract

REASONS FOR PERFORMING THE STUDY:
Chewing lice are widespread and clinically compromising parasites of livestock and equines. Their management is complicated by growing levels of resistance to commonly applied insecticides. Hence, the development of novel approaches to their control is of major clinical interest.
OBJECTIVES:
To assess the effects of incorporating the essential oils of tea tree and lavender into a grooming programme for populations of donkeys with natural infestations of Bovicola ocellatus in the UK and Ireland when louse populations were at their winter seasonal peak.
STUDY DESIGN:
In vivo field trial.
METHODS:
Suspensions of 5% (v/v) tea tree or lavender oil or an excipient only control, were groomed into the coats of winter-housed donkeys (n = 198) on 2 occasions, 2 weeks apart. Louse counts were conducted before each application and 2 weeks later.
RESULTS:
After 2 applications, the groups groomed with lavender or tea tree oil suspensions had a significant reduction in louse intensity, with a mean decline in louse abundance of 78% (95% CI 76-80%). Louse numbers in the groups groomed with excipient only either did not change or increased significantly. Donkey hair length had no effect on the decline in louse numbers.
CONCLUSIONS:
These results demonstrate that the inclusion of essential oil suspensions during grooming can be used to manage louse populations successfully. This article is protected by copyright. All rights reserved.

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Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys

Citation

Christopher J Corbett, Sandy Love, Giles T. Innocent, Ian McKendrick, Jacqui. B. Matthews, Faith A. Burden, Matthew Denwood. Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys. Presented at British Society for Parasitology Spring Meeting.

Authors
Presentation details
Date presented: 
Monday 7 April 2014
Abstract

Cyathostomins, the predominant parasitic nematodes of equids, have developed varying degrees of resistance to all three classes of anthelmintic licensed for use in horses. It is essential that the effectiveness of alternative methods of control for these pathogens are quantified, including incorporating climatic data and the commonly advocated practice of removal of faeces from pasture. Here, we obtained monthly faecal worm egg counts (FWEC, n=4,460 individual counts) from 803 donkeys based at The Donkey Sanctuary (Devon, UK). The dataset also included age, sex, field, FWEC history and previous anthelmintic administrations in each individual, as well as the pasture hygiene management method applied in the field where the donkey was grazed. FWEC were analysed alongside local climatic data using a generalised linear mixed model to assess associations between these variables and each observed monthly FWEC. The preferred model was identified using a model selection algorithm based on penalised likelihoods, and associated a 2.1% decrease in FWEC per day with air frost two calendar months ago (p<0.001) and a 38% lower FWEC in groups with twice weekly manual faecal removal compared to those with no faecal removal (p=0.004). Other weather effects, both alone and as interaction terms with the average FWEC of the field were included in the model, alongside individual FWEC history with anthelmintic administration as interaction terms and date as a single term. Our study identifies factors that may be useful as part of on-going predictive modelling based methods of improving targeted selective therapy.

Online references

Pyrantel resistance in two herds of donkey in the UK

Citation

Edwina Lawson, Faith A. Burden, Hany Elsheikha. January 2015. Pyrantel resistance in two herds of donkey in the UK. Veterinary Parasitology.

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Publication details
Publication date: 
7 January 2015
DOI number: 
10.1016/j.vetpar.2014.12.026
Abstract

Resistance to currently available anthelmintics is a serious phenomenon which is prevalent globally. Cyathostomins are one of the major parasites, and are of primary concern in donkeys. There have been reports of emerging resistance to pyrantel, but the status of pyrantel resistance in donkey populations in the UK is largely unknown. This report investigates pyrantel resistance in two geographically isolated donkey herds in the South West of England. The first herd had suspected pyrantel resistance, with already established resistance to other anthelmintics. In the second herd the efficacy of pyrantel was not suspected at the time the study took place. Faecal Egg Count Reduction Test (FECRT) was carried out, revealing large scale resistance. Eighty one percent of the first herd and 73% of the second herd had a FEC of less than 95% after treatment, and anthelmintic resistance was confirmed using the World Association for the Advancement of Veterinary Parasitology guidelines. These findings indicate that anthelmintic resistance to pyrantel exists in both tested donkey populations and illustrate the continuing development of resistance through different classes of chemotherapeutics.

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Viraemic frequencies and seroprevalence of non-primate hepacivirus and equine pegiviruses in horses and other mammalian species

Citation

Sinead Lyons, Amit Kapoor, Bradley Schneider, Nathan Wolfe, Geoff Culshaw, Brendan Corcoran, Andy Durham, Faith A. Burden, Bruce McGorum, Peter Simmonds. September 2014. Viraemic frequencies and seroprevalence of non-primate hepacivirus and equine pegiviruses in horses and other mammalian species. Journal of General Virology.

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Publication details
Publication date: 
5 September 2014
DOI number: 
10.1099/vir.0.065094-0
Abstract

Non-primate hepacivirus (NPHV), equine pegivirus (EPgV) and Theiler's disease associated virus (TDAV) are newly discovered members of two genera in the Flaviviridae family, Hepacivirus and Pegivirus respectively, that include human hepatitis C virus (HCV) and human pegivirus (HPgV). To investigate their epidemiology, persistence and clinical features of infection, large cohorts of horses and other mammalian species were screened for NPHV, EPgV and TDAV viraemia and for past exposure through serological assays for NPHV and EPgV-specific antibodies. NPHV antibodies were detected in 43% of 328 horses screened for antibodies to NS3 and core antibodies, of which three were viraemic by PCR. All five horses that were stablemates of a viraemic horse were seropositive, as was a dog on the same farm. With this single exception, all other species were negative for NPHV antibodies and viraemia (donkeys (n=100), dogs (n=112), cats (n=131), non-human primates (n=164) and humans (n=362). EPgV antibodies to NS3 were detected in 66.5% of horses, including 11 of the 12 horses that had EPgV viraemia. All donkey samples were negative for EPgV antibody and RNA. All horse and donkey samples were negative for TDAV RNA. By comparing viraemia frequencies in horses with and without liver disease, no evidence was obtained that supported an association between active NPHV and EPgV infections with hepatopathy. The study demonstrates that NPHV and EPgV infections are widespread and enzootic in the study horse population and confirms that NPHV and potentially EPgV have higher frequencies of viral clearance than HCV and HPgV infections in humans.

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Control of the chewing louse Bovicola (Werneckiella) ocellatus in donkeys, using essential oils

Citation

Lauren Ellse, Faith A. Burden, Richard Wall. December 2013. Control of the chewing louse Bovicola (Werneckiella) ocellatus in donkeys, using essential oils. Medical and Veterinary Entomology. 27:4. 408-413.

Authors
Publication details
Publication date: 
1 December 2013
Volume: 
27
Issue: 
4
Page numbers: 
408-413
Abstract

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.

Seasonal infestation of donkeys by lice: phenology, risk-factors and management

Citation

Lauren Ellse, Faith A. Burden, Richard Wall. April 2014. Seasonal infestation of donkeys by lice: phenology, risk-factors and management. Veterinary Parasitology.

Authors
Publication details
Publication date: 
19 April 2014
DOI number: 
10.1016/j.vetpar.2014.04.012
Abstract

A longitudinal study was undertaken over a 21 month period to examine the seasonal abundance of lice infesting donkeys, the risk factors which predispose donkeys to infestation and the effectiveness of louse management. All the lice seen were Bovicola (Werneckiella) ocellatus. A strong seasonal pattern, which was correlated with mean monthly temperature, was observed with higher prevalence and intensity in the cooler, winter months (October-March). Overall infestation in these animals was over-dispersed, suggesting that some individuals are strongly predisposed to infestation. Donkey age and mean hair length were characteristics which affected louse prevalence: older and younger donkeys and donkeys with longer hair harboured the highest numbers of lice. However, the practice of coat-clipping, to reduce the infestation, resulted in a lower louse prevalence only in the summer, suggesting that clipping is not an effective form of louse control in cooler months. Higher louse burdens were associated with larger areas of visible excoriation and hair damage, suggesting that B. ocellatus does adversely impact animal welfare. However, the ability of animal carers to estimate louse presence or absence accurately on an individual donkey was not sufficiently high to allow targeted selective treatment of heavily infested animals to be employed effectively. As animals are housed in closed herds these findings suggest that clipping in the summer and treating all animals with insecticide in late autumn, prior to turn-in may be an effective louse management strategy.

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The evaluation of ethnoveterinary medicines for treating gastrointestinal nematodes in working equids

Citation
Authors
Presentation details
Date presented: 
Wednesday 2 July 2014
Abstract

Introduction: Herbal medicines have been used in human and animal medicine for centuries to treat parasitic diseases; few examples have been investigated for genuine anti-parasitic activity. In developing countries access to effective anthelmintic treatment for livestock is often limited by cost, availability and variable quality. Reports of resistance to benzimadazoles in ruminants in Ethiopia serve as a warning that anthelmintic resistance may also be an emerging problem [1,2]. In light of these issues there is increasing interest in plant remedies as alternatives to synthetic anthelmintics. This study used a participatory rural appraisal (PRA) to identify plants with potential anthelmintic activity in the Oromia region of Ethiopia; five plant extracts were shortlisted and tested for efficacy against cyathostomins using in vitro assays. Current attitudes to ethnoveterinary medicine were discussed.

Methods: Focus group discussions with 29 groups of donkey owners from the Oromia region of Ethiopia explored the use of plants to treat GI parasites in livestock. Current attitudes to herbal medicines were discussed and recorded using thematic analysis. Plants of interest were collected and identified at the National Herbarium, Addis Ababa, Ethiopia. Plants were shortlisted for in vitro tests based on four criteria; ranking in the PRA, supportive literature, no evidence of toxicity and availability. Hydro-alcoholic extraction of dried plant material from shortlisted species was performed. The efficacy of extracts was evaluated in the egg hatch assay (EHA) using cyathostomin eggs recovered from the faeces of donkeys at the Donkey Sanctuary, UK. Dose response curves were produced and ED-50 values calculated using probit analysis.

Results: The focus groups identified 21 plants used as anthelmintics in livestock. A general move away from traditional medicines in the younger generation was observed, although when asked if they would use plants in future many would consider this if they had been tested scientifically and were approved by professionals. The five plants shortlisted for in vitro analysis were Acacia nilotica, Cucumis prophetarum, Rumex abysinnicus, Vernonia amygdalinia and Withania somnifera. Three showed efficacy in the EHA; Acacia nilotica, Cucumis prophetarum and Rumex abysinnicus , with EC-50 values of 0.7, 1.1 and 1.3mg/ml respectively.

Conclusion: Three out of five of the plants identified in the PRA showed efficacy in vitro suggesting that plant remedies used by livestock owners in the Oromia region of Ethiopia may contain compounds with genuine anthelmintic activity. Evaluation of current attitudes suggests that plant remedies are not used unless there is no other option, but that they would be considered should scientific evidence of efficacy and safety be presented to them by animal health professionals [3]. It is therefore essential that a randomised controlled trial is used to verify whether in vitro anthelmintic activity can be translated in vivo and thus whether the plants identified in this study have potential as safe alternatives to synthetic anthelmintic drugs. This study has highlighted that local practices pertaining to the health of working equids are a rich source of information that may help to inform sustainable and effective treatment strategies in future.

Online references

The P-glycoprotein inhibitor ketoconazole causes a reversion to ivermectin sensitivity in cyathostomins in vitro

Citation

Laura Peachey, Jacqui. B. Matthews, Gina L. Pinchbeck, Faith A. Burden, Nikki Stradling, Jane Hodgkinson. The P-glycoprotein inhibitor ketoconazole causes a reversion to ivermectin sensitivity in cyathostomins in vitro. Presented at British Society for Parasitology Spring Meeting.

Authors
Presentation details
Date presented: 
Monday 7 April 2014
Abstract

Anthelmintic resistance is a major veterinary and public health issue globally, of most concern is the level of resistance to the macrocyclic lactones. Recent studies have identified a role in resistance for the ATP binding cassette (ABC) drug transporters, P-glycoproteins (P-gps). This study demonstrates the effect of the P-gp inhibitor ketoconazole on the efficacy of ivermectin (IVM) against equid cyathostomin larvae using the larval migration inhibition test (LMIT). Third stage cyathostomin larvae (L3) were cultured from two populations; 1) with recent history of IVM resistance in vivo and 2) naive to anthelmintic exposure. The sensitivity to IVM in each group (n=8) was characterised using the LMIT. The IVM LMIT was repeated for each sample with and without the addition of 10µM ketoconazole. Probit analysis was performed on grouped data from each population to give LC-50 values. The LC-50 value for IVM in Populations 1 and 2 was 4.9 and 2.4µg/ml respectively indicating that Population 1 has a resistant phenotype in comparison to Population 2. Addition of 10µM ketoconazole to IVM in Population 1 caused a drop in LC-50 value from 5.8 to 1.6µg/ml. In Population 2 the effect of the addition of ketoconazole was negligible (1.1 to 0.9µg/ml). This study demonstrates that the P-gp inhibitor ketoconazole causes reversion to a sensitive phenotype in IVM-resistant cyathostomins, inferring that P-gps play a role in their resistance to IVM. This work will be corroborated by investigation into P-gp genes and their expression in cyathostomins.

Online references

Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys

Tagged:  
Citation

Christopher J Corbett, Sandy Love, Giles T. Innocent, James McKendrick, Jacqui. B. Matthews, Louise Matthews, Matthew Denwood, Faith A. Burden. Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys. Presented at British Society for Parasitology Spring Meeting.

Authors
Presentation details
Date presented: 
Monday 7 April 2014
Abstract

Cyathostomins, the predominant parasitic nematodes of equids, have developed varying degrees of resistance to all three classes of anthelmintic licensed for use in horses. It is essential that the effectiveness of alternative methods of control for these pathogens are quantified, including incorporating climatic data and the commonly advocated practice of removal of faeces from pasture. Here, we obtained monthly faecal worm egg counts (FWEC, n=4,460 individual counts) from 803 donkeys based at The Donkey Sanctuary (Devon, UK). The dataset also included age, sex, field, FWEC history and previous anthelmintic administrations in each individual, as well as the pasture hygiene management method applied in the field where the donkey was grazed. FWEC were analysed alongside local climatic data using a generalised linear mixed model to assess associations between these variables and each observed monthly FWEC. The preferred model was identified using a model selection algorithm based on penalised likelihoods, and associated a 2.1% decrease in FWEC per day with air frost two calendar months ago (p<0.001) and a 38% lower FWEC in groups with twice weekly manual faecal removal compared to those with no faecal removal (p=0.004). Other weather effects, both alone and as interaction terms with the average FWEC of the field were included in the model, alongside individual FWEC history with anthelmintic administration as interaction terms and date as a single term. Our study identifies factors that may be useful as part of on-going predictive modelling based methods of improving targeted selective therapy.

Online references
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