Veldonderzoek naar Cyathostominae in de provincies Utrecht en Noord-Holland

Abstract

It is possible to treat Cyathostomin infections with benzimidazoles, pyrantel or macrocyclic lactones (ivermectin and moxidectin). Since the eighties anthelmintic resistance in the Cyathostomins has been found against benzimidazole and pyrantel. Until recently the macrocyclic lactones were the only group of anthelmintics for which resistance was not found. However, recently Brazilian research (2008) showed for the first time also resistance against ivermectin.

Because of a generally widespread and increasing occurrence of anthelmintic resistance of parasites of food animals, anthelmintic drugs have been made prescription only medicines since 1 july 2008. This should reduce the enormous use of anthelmintics, and provide a better rationale for its use based on veterinary advice. In view of this we started a study on the repeatability of the McMaster worm egg count technique as an aid for the proper use of anthelmintics and on the use of anthelmintics on horse farms and whether application of these drugs occurs blind or based on knowledge about the infection.

In August and September 2009 we visited 28 horse farms in Utrecht and Noord-Holland. At each farm we collected stool samples from two to five mature horses (older than four years) and took an interview with the horse owner. In the laboratory the EPG of each stool sample was determined with the help of the McMaster method and a larval culture was performed.

Of the horse owners about 50 % purchase anthelmintics without a recipe of a veterinarian. They buy them through the internet or from non registered sales. It was found that many horse-owners apply anthelmintics too often. On average horses were treated 3,0 times per year. No Strongylus vulgaris larvae were found in any of the faecal cultures. The repeatability of the McMaster method was found to be high with r2 being 0.797 (P<0.001) for sub-samples examined within the same faeces sample, and r2 of 0.706 (P<0.001) for the repeatability of samples taken three consecutive days.