There are a multitude of different brands of horse wormers available on the market today, but if you actually check the active ingredient of each brand you will discover that many contain exactly the same active ingredient!
The active ingredients in horse wormers available in the UK belong to one of only four different chemical families. These are:
• Macrocyclic lactone (ML) - Both moxidectin and ivermectin belong to this group; moxidectin from the milbemycin ML sub-group, and ivermectin from the avermectin ML sub-group. They both have similar properties but have different chemical structures and a different spectrum of activity.
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• Pyrimidines - pyrantel
• Benzimidazole - fenbendazole and mebendazole
• Isoquinoline pyrazine - praziquantel
The mode of action of each active ingredient is the same in that they kill parasites by causing paralysis, the exception being benzimidazoles which cause the parasite to starve.
Each active ingredient controls a different range of parasites and has a different dosing interval as summarised in the chart below.
Some wormers are available that contain a combination of two different active ingredients, and offer control accordingly. |
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