Tillotson Equine                                                                                                                                                                                                                                                                             

              Internal Medicine Mobile  Services

Parasite Control/Deworming Protocol – New and Improved! 

Parasite Resistance – It is becoming a real problem.  There are no new drugs on the horizon for deworming horses, and parasite resistance has been documented in all classes of anthelmintic drugs on the market today.   

To properly develop a deworming program, a fecal exam should be performed on each horse at an appropriate period of time after it was last dewormed.  This time period varies depending on the drug that was most recently used to deworm.  The recommendations below are based on the known egg reappearance period (ERP) for the dewormers that are most often used.

Moxidectin (ERP = 12 weeks)

Fecal exams should be performed 12 weeks after a horse was dewormed with Quest or Quest Plus

Ivermectin (ERP = 8 weeks)

            Fecal exams should be performed 8 weeks after deworming with ivermectin products

Pyrantel (ERP = 6)

            Fecal exams should be performed 6 weeks after deworming with Pyrantel products such as Strongid. 

Benzimidazole (ERP = 6)

Fecal exams should be performed 6 weeks after deworming with Panacur or other Benzimidazole products

Why do a fecal exam? 

A fecal exam should be performed to determine the level of parasitism in the individual horse and characterize that horse as a “low”, “moderate” or “high” shedder.  This makes a big difference!  If your horse is a low shedder, then using the typical deworming protocol of rotational deworming every 6-8 weeks is no longer recommended.  Using this protocol will likely contribute to parasite resistance. 

The goal is to have less pasture contamination of parasites in general and to minimize resistance of parasites to the drugs that we have available on the market.  By deworming the low shedders less frequently and targeting the high shedders with more aggressive protocols, we can achieve these goals!

Last modified: 12/30/09