Wormers…what to use and when to use them is a question many horse people ask. Choosing the proper wormer at the correct time of year can be a little confusing and sometimes overwhelming. When it comes to worm control, a generic solution can never be ideal but often this is what we do. Every horse is an individual and every situation is unique and it is very important for us to use wormers responsibly. If we use wormers too frequently or unnecessarily, we could eventually reduce their effectiveness in controlling parasites, better known as resistance. But the real question is "Which wormers affect what parasites and when do I administer them?"
Horses typically get worms when turned out with previously infected horses or when they are turned out in a contaminated pasture. In both situations, the horse is likely to become infected. Pastures become contaminated with the eggs and larvae or parasitic worms through the manure of an infected horse's manure which then mixes in the grass of the pasture. As your horse grazes, the eggs and larvae are ingested and pastures can remain infected for a considerable amount of time.
When rotating your worming products, make sure you are choosing a different ingredient not just a different brand. Develop an effective worming programme on an annual basis using tactical worming for specific parasites and rotate active ingredients during the grazing season and not each time you worm your horse. The three basic chemical groups are:
MACROCYCLIC LACTONES - Ivermectin and Moxdectin - Brand Names: Zimecterin; Zimecterin Gold; Horse Health Ivermectin; Bimectin; Ivercare
TETRAHYDROPIRIMDINES - Pyrantel - Brand Names: Exodus; Strongid; OPyrantel Pamoate Paste; Strongid C; Strongid C 2X
BENZIMIDAZOLES - Fenbendazole, Mebendazole, Oxibendazole - Brand Names: Panacur; Safe-Guard; Safe-Guard Equi-Bits; Anthelicide EQ
Now on the market is Praziquantel which is specifically used for tapeworm control, however, this product must be used in conjunction with the products based on the three groups above.
PRAZIQUANTEL - Praziquantel - Brand Names: Equimax; Quest Plus; Zimecterin Gold
Recently, there has been evidence of a resistance building to products in the Benzimidazole group in certain areas so it is best to speak to your veterinarian to get fully informed before relying on products within this group to control worm burdens.
Although most of the leading brands of horse wormers are effective against adult redworms (determine that your horse is infected with worms by taking a dung sample and having an egg count done) there are times when you will need to worm tactically to treat for specific worm types at certain times of the year. Which ever chemical group you choose to use on an annual basis, you will still need to dose tactically to control encysted small redworm, tapeworm and bots. Below, is a typical schedule that can be followed to treat the type of worm during specific times during the year.
Treat for Encysted Small Redworm Larvae during the winter months with Equest or Panacur 5 Day Equine Guard
Treat for Bots during the winter months with Equest, Equest Pramox, Eqvalan, Eraquell, Vectin, Eqvalan Duo or Equimax
Treat for Tapeworm in Spring & Autumn with Strongid P, Pyratape P, Equimax, Eqvalan Duo, Equest Pramox or Equitape (EQUITAPE TREATS FOR TAPEWORM ONLY)
Treat for Large and Small Redworm during the grazing period with Equest, Strongid P, Pyratape P, Eqvalan Duo, Panacur, Telmin, Eqvalan, Eraquell, Vectin or Equimax.
All products can be used year round for Large and Small Redworm treatment (WITH THE EXCEPTION OF EQUITAPE AND BEARING IN MIND THE ABOVE ADVICE WITH REGARD TO BENZIMIDAZOLES) as part of a worming plan.