Preliminary Data from Six Years of Selective Anthelmintic Treatment on Five Horse Farms in France and Switzerland

Anthelmintic resistance (AR) of small strongyle populations (cyathostomins) against products of the benzimidazole and tetrahydropyrimidine classes occurs now worldwide and there is an increasing number of reports also regarding macrocyclic lactones. Consequently, and in order to maintain an appropriate horse parasite control, alternative control schemes must be evaluated under field conditions. Here we present a six-year field study on the administration of the so-called selective or targeted selective anthelmintic treatment (SAT) concept. In this study on five horse farms in France and Switzerland, 757 fecal samples from 93 equids (90 horses, 3 ponies) have been taken twice a year (between early and late spring and between early and late autumn) from autumn 2014 to spring 2020 and processed by a McMaster technique. From a total of 757 samples, only 263 (34.7%) had a fecal egg count ≥200 EpG and needed an anthelmintic treatment. This small number of fecal samples ≥200 EpG demonstrates the considerable potential for a long-term reduction of the number of anthelmintic treatments and the anthelmintic pressure by using the SAT-programme.

Gastrointestinal parasites of the Polish primitive horses from the Biebrza National Park

Summary Thirty-one Polish primitive horses (Equus caballus) from three herds (two from the reserve and onefrom the stable) were dewormed with ivermectin+praziquantel and examined for the gastrointestinalparasite fauna. A total of 21.231 parasites were collected from the faeces at 24, 36 and 48 hoursposttreatment. There were 35 nematode species, one cestode and one botfl y larva. Strongyloideswesteri infection was confirmed pretreatment by faecal sample examination and no threadwormspecimens were found after deworming. Large and small strongyle prevalence was 90 % – 100 % and represented by 31 species. Among a total of 25 cyathostome species recovered (from 19 to 24in each group), five species (C. catinatum, C. minutus, C. longibursatus, C. nassatus and C. ashworthi)had a prevalence of 100 % in three groups of horses. Meanwhile 14 species were 100 % prevalent in one herd. A total of six large strongyle species were found in adult horses. Oxyuris equiwas recorded in 60 – 100 % of the horses while Parascaris equorum was detected in 100 % of foalsand 16.7 % – 30 % of adult mares. Habronema muscae was found in 30 % of the horses from onefree-ranging herd. Tapeworms (Anoplocephala perfoliata) were found in 90 % of the horses from onefree-ranging group, whereas botfl y larvae (Gasterophilus intestinalis) were found in 50 – 80 % of allsurveyed horses. The present results are compared with earlier studies of Polish primitive wild horsesfrom similar reserves in Poland. A total of 36 gastrointestinal parasite species were recorded fromwild and stabled horses from the Biebrza National Park. This is in comparison with 35 such speciesin free-ranging and stabled horses from the Roztocze National Park and with 28 such species offree-ranginghorses from the Popielno forest reserve. Among parasites recovered, the highly prevalent S. vulgaris, tapeworms and botfl y larvae pose aserious risk of serious abdominal disorders in horses.

Cyathostominae distribution in experimentally infected ponies

Summary Nine ponies were experimentally infected with third stage cyathostome larvae. These animals were examined post-mortem for small strongyle infections from October 2011 to January 2012. Seventeen species of the following Cyathostominae genera were identified: Coronocyclus, Cyathostomum, Cylicocyclus, Cylicostephanus, Gyalocephalus and Petrovinema. Of the 17 species of Cyathostominae recovered, Cyathostomum catinatum, Cyathostomum alveatum and Cylicocyclus nassatus were the most prevalent (100 %). From the entire population of Cyathostominae, 65.6 % were located in the caecum and only 34.4 % in the colon. Only 1,736 (24,6 %) females and 5,329 (75,4 %) males were observed. There was a significant difference between the number of males and females in the genus Cyathostomum, Cylicocyclus and Gyalocephalus.