There is now evidence that parasitic worms are slowly building resistance to worming drugs. Continued exposure has meant that worm populations have genetically evolved to survive certain treatments. The more that drugs are used the more likely resistance will develop. Treatment to cover everything just in case ( so that i know i’m covered) also leads to resistance.
The rate of resistance to worming drugs can be slowed down. It is important to treat at the recommended dose, under dosing will help speed up the resistance, but beware over dosing may be harmful to the pony.
Targeting wormers by using worm counts and tests and treating only ponies that need treating. There have been studies that show that in any given population of horses/ponies approximately 80% of parasitic worms will be carried by only 20% of the animals, therefore targeting may prove less costly and help to reduce build up resistance.
Worming at the time of the year when the parasite burdens are at their worst. It is important to bear in mind unseasonal weather conditions which may have an effect
Pasture management, not over stocking, co-grazing with other livestock if possible. poo-picking a minimum of twice a week, harrowing in summer months.
Quarantine new ponies arriving at the yard until they have been tested and then treated accordingly.
Be careful where you let your ponies graze when they are away from home, shows, and other equestrian venues.
Test to see if your treatment is working. Do a worm count before treatment, if there is a need to treat do another worm count two weeks after treatment, there should be reduction of approx 90%.
Testing kits are usually available from the stockists of wormer drugs.