Latest developments in testing for equine helminths

Abstract

Background: Helminths are found in most grazing horses. When high burdens occur, these worms can cause serious disease. Historically, the threat of parasite-associated pathology led to control programmes that comprised regular all-group anthelmintic treatments. Unfortunately, this approach encouraged selection for drug resistance, in particular, in cyathostomins. For over 25 years, parasitologists have recommended that prophylactic treatments be avoided and, instead, tests be applied to indicate which helminths are present in populations and at what levels worms are found in, or excreted by, individuals. These evidence-based approaches have had variable uptake across regions. In the UK, there has been a gradual rise in testing, especially the use of faecal egg count analysis to inform treatment decisions to reduce egg shedding from horses that contribute most to pasture contamination. Antibody-based tests are also being used to enable assessment of burdens of Anoplocephala perfoliata and cyathostomins in order to provide information on the presence of these parasites in populations.

Aim of the article: This article provides an update on how to use diagnostics alongside improved pasture management in equine worm control programmes to reduce anthelmintic treatment frequency.