Gastrointestinal Strongyles Egg Excretion in Relation to Age, Gender, and Management of Horses in Italy.

Antonio Scala,Giampietro Sedda,Claudia Tamponi,Giuliana Sanna,Vincenzo Veneziano,Giulio Predieri,Antonio Varcasia,Giorgia Dessì,Maria Grazia Cappai,Francesco Buono

doi:10.3390/ani10122283

Antonio Scala, Giampietro Sedda + Show 8 more

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https://doi.org/10.3390/ani10122283

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Abstract

Current equine helminth control strategies play a key role in strongyle epidemiology and anthelmintic resistance and have led to the recommendation for new treatment plans, which include diagnostic and efficacy surveillance. Assessing the equine strongyle distribution patterns would thus be useful and this study describes the strongyle prevalence in the equine population in Italy through coprological analysis and coproculture. In addition, individual data on each animal were collected in order to identify risk factors associated with strongyle egg shedding. Of the total number of stables investigated, 86.4% were found to have at least one positive animal and a 39.5% prevalence of strongyle egg shedding with a mean eggs per gram (EPG) of 245. A total of 80% of the total recorded EPG was shed from 12.8% of positive horses, thus confirming the need for new targeted intervention strategies. Significant differences in parasite prevalence were found based on season, sex, geographical distribution, management and rearing system, and breed. Significantly lower EPG values were found in horses that had received anthelmintic treatment, and macrocyclic lactones (MLs) were the most effective. Lastly, although large strongyles are more pathogenic, horses in Italy are mainly burdened by small strongyles, which pose an important animal health risk requiring continuous parasitological monitoring.

Highlights

Equids are exposed to a large number of helminths throughout their lives [1], above all gastrointestinal strongyles (GIS)
The moderate egg shedding value that we identified could be associated with two main factors: (i) the time between the last anthelmintic treatment and fecal egg count; (ii) encysted and arrested larvae of small strongyles that can be responsible for a negative FEC, which becomes positive over time without reinfestation
Our study has shown that gastrointestinal strongyles, above all small strongyles, are still widespread in Italy, with prevalence rates of 39.5% among the horses monitored, and with 21.4% of horses shedding more than 200 eggs per gram (EPG)

Summary

Introduction

Equids are exposed to a large number of helminths throughout their lives [1], above all gastrointestinal strongyles (GIS) (large and small strongyles). Horses can harbor significant worm burdens without showing clinical symptoms, specific syndromes have been ascribed to infections by cyathostomins and large strongyles [4,5] Because of their high pathogenic role, large strongyles, especially Strongylus vulgaris, were used as the primary target of anthelmintic treatment. The mass emergence of cyathostomin larvae in the large intestines can cause larval cyathostominosis, which is characterized by watery diarrhea, dehydration, and ventral oedema, with a case-fatality rate of around 50% [4,7,10] Because of their large diffusion, cyathostomin parasites are considered the main targets of parasite control strategies [6,7]

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