anthelmintic resistance

Clinical trial on the efficacy of moxidectin oral gel formulation on donkeys naturally infected by cyathostominae

Laura Pacifico
F. Buono
Presentation date

Donkeys and horses share several parasites including the small strongyles, Cyathostominae. Moxidectin (MOX), a compound of macrocyclic lactones, has a wide range of ecto and endoparasitic activity in many species. For horses, MOX is available as oral gel formulation that provides excellent and long-lasting efficacy against nematodes such as large and small strongyles. There is a paucity of data available on the efficacy of anthelmintics used in donkeys (Veneziano et al., 2011). Therapeutics, such as antiparasitic compounds, are often administered to donkeys on the basis of dosage and intervals recommended for horses, because very few drugs have donkey-specific label indications (Grosenbaugh et al., 2011). The objective of the present study was to evaluate the field efficacy and Egg Reappearance Period (ERP) of MOX oral gel up to 84 days at horse dose against natural infection of Cyathostominae in donkeys.

Country
Published as conference proceedings

Assessment of the efficacy of the anthelmintic moxidectin against cyathostomins at The Donkey Sanctuary: analysis of new and historical data using novel statistical methods

Status
Applicant(s)
Methodology

Statistical analysis of retrospective data. Phase one involves transfer of data to the lead investigator for analysis using Marcov chain Monte Carlo (MCMC) statistical methods. Phase two involves combined analysis of all FECRT data collected over the three sampling times to identify i) temporal trends in the development of resistance, ii) evidence for differential rates of development of resistance, and iii) evidence for particular groups of animals for which the rate of development of resistance seems to be accelerated compared to the other groups. Phase three of the project will involve communication of the findings to the research and clinical teams at The Donkey Sanctuary, and subsequent discussions regarding the implications of these findings for routine endoparasite control.

Aims

The overall aim of the project is to analyse the patterns of changing drug resistance to the clinically important anthelmintic Moxidectin within the small strongyle (cyathastomin) parasite population at The Donkey Sanctuary. Overall control of the endoparasite population is a complex issue so the clinical recommendations generated as part of this proposed project will be given within the context of a much larger, previously completed collaborative research project. An important part of this project is to discuss findings with the clinical and research teams at The Donkey Sanctuary in the context of recommendations for both routine annual dosing of all animals and treatment of animals with clinical disease and/or welfare compromise due to endoparasites.

Objectives

1) To examine faecal egg count reduction test (FECRT) data gathered as part of routine annual anthelmintic use at The Donkey Sanctuary autumn/winter 2018/2019, in order to assess the current efficacy of Moxidectin using state of the art statistical methods. 2) To use bespoke statistical methods to analyse the most recent FECRT along with similar data during autumn/winter 2010 and 2013 to identify trends in the pattern of resistance development, including associations between accelerated rates of resistance development and particular management patterns. 3) To interpret the findings of this project in relation to those of previous projects, and to contribute to the established recommendations for best practice to minimise the rate of development of drug resistance at The Donkey Sanctuary.

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