Things You'll Need
- Horse wormers
Instructions
Follow a two-year schedule and rotate the drug you use annually. Use one chemical type of drug in Year 1, and a different type in Year 2, and follow an alternating pattern. This helps in the prevention of resistance. If you use the same drug constantly the worms that are not killed by the drug will continue to breed and their offspring will be born resistant.
Ensure you use the correct drug at the optimum time to target different families of worms. There are four different classes used in horses. Benzimidazoles and probenzimidazoles are used for treatment for encysted worms (hibernating worms over the winter period that form cysts inside the horse) over a five-day period, and to treat all worms. However, resistance has been reported. Macrolytic lactones and ivermectin are used for treatment of bots and all worms except for encysted strongyles and tapeworm. Tetrahydropyramidines, levamisole and pyrantel/morantel can be used to treat all worms except encysted worms. Praziquantel treats tapeworm treatment
Understand the best time to worm for individual species for optimum effectiveness. Most worms should be treated regularly throughout the year at an interval dictated by the brand of wormer used, which is usually between six and 13 weeks. Treat for bots in early winter, in spring and autumn for tapeworm, and early February and late October for encysted strongyles.
Remove bot eggs off the horse's coat when they appear in the autumn to prevent the horse from licking them off. They appear as small yellow eggs and can be picked off or removed with a comb.
Employ other methods of worm control regularly, including removing horse droppings out of fields every two or three days, resting the fields monthly and rotating them with other grazing animals such as sheep or cattle.
Isolate new animals until they have been treated for worms, and keep them separate for a few days to prevent the spread of any worms.
Have your veterinarian complete a fecal worm count on a regular basis to ensure your actions are having a positive effect. He can tell you whether the horse needs further worm treatment.