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Deworming

Deworming Your Horse

Traditionally, deworming of horses has been performed on a rotating schedule, using a different dewormer every 8 weeks. For a long time, this program worked well, and we were successful in almost eliminating the large strongyle from our equine population.  However, in the last 5-10 years we have seen a major increase in resistance of worms to our most commonly used dewormers.  This is leaving some of our equine patients vulnerable and owners frustrated.

So, what can we do to help prevent resistance in your herd? The best way to monitor your herds worm burden and resistance in your herd is with a fecal egg count (FEC). With a FEC we can evaluate how many eggs per gram (epg) your horse is shedding and categorize them into one of three categories:  Low shedder (<200 epg), Moderate shedders (200-500 epg) and High shedders (>500 epg).  We then base your horses deworming schedule on their category.  Every horse will shed a different amount of eggs.

Even if a horse is in a pasture with a high shedder, doesn’t mean that they will be a high shedder as well. The difference in the parasite burden between horses is caused by the ability of each horses immune system to fight against the parasite, not just exposure.  Some horses can keep their own parasite burden low, while others cannot.  By running a FEC we can classify your horse into one of the three categories and help reduce the amount of different dewormers the parasites are exposed to, thus reducing resistance.

So how do you know if the parasites on your farm are resistant to a certain dewormer or not? By performing a FEC before deworming and then one 10-14 days after deworming, we can calculate your herds Fecal Egg Count Reduction.  Counts that don’t decrease by more than 90% are resistant.  Doing a Fecal Egg Count Reduction test should be performed every 2-3 years.

Preforming a fecal egg count on your herd can help reduce the number of times you have to deworm per year, saving you money and helping insure that we can continue to keep our horses as healthy as possible.   Please contact us for instructions on how to submit a fecal sample for your horse today.

 

Deworming Schedule Based on FEC

  • Low Shedders (<200 epg)
    • Spring (March) – Ivermectin or Moxidectin
    • Fall (October) – Ivermectin w/ Praziquantel or Moxidectin w/ Praziquantel (Quest +)
  • Moderate Shedders (200-500 epg)
    • Spring (March) – Ivermectin or Moxidectin or double dose of Fenbendazole for 5 days (Panacur Power Pac)
    • Late Summer (July) – Pyrantel Pamonate or Fenbendazole
    • Early Winter (November) – Ivermectin w/ Praziquantel or Moxidectin w/ Praziquantel (Quest +)
  • High Shedders (>500 epg)
    • Spring (March) – Ivermectin or Moxidectin or double dose of Fenbendazole for 5 days (Panacur Power Pac)
    • Summer (June) – Pyrantel Pamonate or Fenbendazole
    • Fall (After Frost) – Ivermectin w/ Praziquantel or Moxidectin w/ Praziquantel (Quest +)
    • Winter (December) – Pyrantel Pamoate or Fenbendazole

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