Helminth control used by trainers of thoroughbreds in England.

This article presents the results of a telephone survey investigating the methods used by thoroughbred horse trainers in England to control parasitic worm infections. The study found the methods — primarily frequent use of anti-parasitic drugs — to be somewhat successful, but also highlighted some potential risks and shortcomings.

Survey Method and Main Findings

• A telephone survey was conducted at 106 thoroughbred training yards to assess the methods used to control parasitic worms in horses.
• It’s notable that most horses had access to grass, which increases their risk of catching parasitic worm infections.
• The key method of control was found to be the use of anthelmintics – drugs that expel or destroy parasitic worms.
• The survey showed that 44 percent of trainers reported observing clinical signs of nematode infections suggesting that, although popular, the use of anthelmintics was not completely successful in preventing worm infections.

Frequent Anthelmintic Dosing

• Trainers regularly administered doses of anthelmintics to their horses, with 40 percent treating their horses every four to six weeks and 25 percent treating every seven to eight weeks.
• However, this strategy might not prevent the introduction of anthelmintic-resistant nematodes, a concern in many areas of medicine where frequent and unnecessary use of medication can breed resistant strains of bacteria or viruses.

Control Schemes and Veterinary advice

• Upon arrival at new training yards, horses usually received a dose of anthelmintic.
• However, the authors suggest these strategies would unlikely prevent the introduction of anthelmintic-resistant nematodes or deal with encysted cyathostomes, another type of parasitic worm.
• The control schemes for parasitic worms were largely designed by the trainers themselves. Only 42 percent of trainers were found to base their choice of anthelmintic on veterinary advice, which might be limiting the success of such schemes in preventing parasitic worm infections.