There are four main classes of anthelmintics (wormers). These are:
- Benzimidazoles: eg. fen/me- bendazole
- Tetrahydropyrimidines: eg. pyrantel embonate
- Macrocyclic lactones: eg. Iver/aver -mectins
- Praziquantel based wormers (tapeworm treatment ONLY)
Using the same class of wormer every season will increase the chance of resistance developing. It is therefore important to rotate the type of wormer used after each grazing season.
Targeted Worming Programmes
Tailored programmes ensure you target specific worms with an effective product at the correct time of year.
Additionally using faecal worm egg count testing during the grazing season (April to October) will then dictate how and when wormers are used during this period. Many companies, commercial laboratories and veterinary practices, can perform faecal worm egg counts. It is important to remember that faecal egg counts cannot detect encysted small redworms or tapeworm eggs, so it is important to treat for these parasites at certain time points during the year.
There is a blood test available to test horses for the likelihood of tapeworm infection which can be used to determine if a tapeworm treatment is required.
During the grazing season an alternative product should be used for each subsequent year’s grazing season so that the three main types/classes of anthelmintic (praziquantel is excluded from this rotation as it only treats tapeworms)are used on a rolling three-year basis.
If you have a new horse, it is sensible to worm him with a product or combination of products that will kill all types and stages of roundworm (including encysted and inhibited small redworm) and tapeworm. Stable him for 48 hours after worming before turnout to allow the wormer to take effect and prevent viable eggs from being deposited on the pasture.
To download your equine worming record card click here