While information on anthelmintic resistance in equine parasites has been available for a long time, the equine industry has been very slow to acknowledge or respond to it. Numerous studies have documented the increasing prevalence of resistance to the different commercially available drug classes. Not surprisingly, parasitologists have strongly recommended reducing treatment intensity by moving away from the traditional calendar-based treatment protocols, which are based upon anthelmintic treatment of all horses at regular intervals year-round. Current recommendations involve regular analysis of fecal samples for the presence of parasite eggs before decisions on treatment are made. Several questionnaire-type surveys have revealed that despite these recommendations, horse owners in many countries still rely on frequent, regular anthelmintic treatments without any consideration of the parasite species that may be involved and the efficacy of anthelmintic drugs used against those parasites.

Several possible reasons may account for this approach:

• Parasitologists lack effective channels of communication to convey their message;

• The anthelmintic resistance has not yet reached a level that represents a threat to equine health;

• The calendar-based approach has been much easier to follow than the more complicated treatment strategies based on testing fecal samples; and

• In many countries, cheap anthelmintic drugs have been available over the counter, so horse owners have not had to retain the services of a veterinarian, thereby lessening the expense.

Singly or collectively, the foregoing factors have made it very difficult to change old habits when it comes to parasite management on horse farms.

However significant these obstacles, major changes in parasite management on farms have been observed in recent years. Awareness of anthelmintic resistance among equine veterinarians and their clients appears to be increasing. As a result, testing for parasite eggs in fecal samples is becoming more and more common