Overuse of deworming products is playing an important role in the development of parasite resistance. There are only a small number of drugs that will kill parasites available and no new products are being developed, so we must make what we have last!

It is important to only deworm your horse if he needs it, not by following the tradition of deworming on a set rotation every 2 months. In fact, some horses may only need to be treated twice a year. It all depends on how effectively your horse’s immune system functions to protect him from parasites in his environment. It is said that 20% of the horses in a group are responsible for 80% of the parasite load.

By counting the number of worm eggs your horse sheds in a gram of feces we can categorize him into one of three different categories: high, medium, or low shedder. We will then develop a de-worming program based on your horse’s immunity to worms and his environment. For the program to be effective, all horses will require fecal analysis twice yearly to determine parasite load. De-worming protocols for each of these categories is below. Treatments will be performed at specific times of the year to target the life cycle of the parasites.  Horses can be started on the program at any time of the year, fecal exams will be performed and your horse will be worked towards the ideal times for analysis (January and October) as you progress through the program.


A Fecal Egg Count is performed on ALL horses at this time and repeated in January. For horses on this program, this count gives us a clear picture of how susceptible your horse is to parasites.

Each horse is classified according to the number of parasite eggs found in a gram of feces (eggs per gram or "epg"):

LOW (<200 epg)

MODERATE (200-500 epg)

HIGH (>500 epg)


  • October 1st  (fall)
    • Perform fecal analysis.
    • Administer ivermectin plus praziquantel.
  • January 1st (spring)
    • Perform fecal analysis.
    • Administer moxidectin.
  • Continue to monitor fecals in October and January for one more cycle.  If the horse remains a low shedder, continue treating in October and January as outlined above.  Perform a fecal analysis every year in October to ensure maintenance of Low Shedder status.


  • October 1st (fall)
    • Perform fecal analysis.
    • Administer ivermectin plus praziquantel.
  • January 1st (spring)
    • Perform fecal analysis.
    • Administer moxidectin.
  • On this program, Moderate Shedders often become Low Shedders over time.  Twice yearly fecal analyses will help us determine when this occurs.  When consistently a Low Shedder, fecal analysis can be decreased to every year to ensure maintenance of Low Shedding status while following the Low Shedder Program.



  • October 1st
    • Perform fecal analysis.
    • Administer ivermectin plus praziquantel.
  • December 1st
    • Administer oxibendazole.
  • January 1st
    • Perform fecal analysis.
    • Administer moxidectin.
  • April 1st
    • Administer oxibendazole.
  • High shedders should have an additional fecal analysis performed 10-14 days after administration of any dewormer to ensure that resistance has not already occurred against a given product.  Because we feel that this is critical to the success of the program we will perform this service at no extra charge to our clients.

No plan includes deworming horses through the summer months...why not?

All Horses:  MAY –SEPTEMBER: No treatments are needed because it is too hot for transmission. Most worm eggs will not survive and develop into larvae, and those few that do make it to larvae will rapidly die. So egg shedding is of no concern during this time. Save money and reduce the selection for drug resistance by not treating horses with an anthelmintic (dewormer) during the summer months (unless there is a specific clinical need for such treatment).

From: Kaplan, RM. Suggested Worm Control for Adult Horses in Florida. Florida Equine Institute and Allied Trade Show. September 2009.



Common deworming drugs and their brand names:


Ivermectin plus praziquantel:
"Zimectrin Gold"


Moxidectin plus praziquantel:
"Quest Plus"

"Panacur Power Pak" (5 days of fenbendazole at the double dose)

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