Controlling worms requires a combination of cleanliness, pasture management and dewormers.The following are general recommendations for how to treat worms in horses and I recommend that you consult a veterinarian for an individualised treatment program.
Pasture and feeding
Removal of manure from small pastures should occur twice weekly. On larger pastures you’ll need to perform frequent mowing/harrowing, animal rotation and avoiding overcrowding. Horses should be removed from pastures for a minimum of 6-8 weeks and adding sheep or cattle helps to decrease parasite numbers. It’s also recommended to group horses in pastures according to age to protect young horses from exposure. As we as always feeding out of tubs and placing hay in racks to avoid contamination with manure.
Faecal Egg Count (FEC)
FEC is a measure of the number of strongyle or tapeworm eggs per gram of manure. A FEC testing kit will provide you with an accurate measure and therefore help determine which wormers to use. Test kits can be acquired at local produce stores or online.
The four main de-worming chemical groups are benzimidazoles (white drench), Tetrahydropyrimidines (clear drench), macrocyclic lactones, and pyrozine. It is recommended that chemical groups be rotated every 12 months to avoid a build-up of resistance. In mature horses focus on control of strongyles with a product like AbFen™ which treats against large and small strongyles, tapeworms and roundworms. Depending on climate, 1-2 yearly treatments are enough to prevent their occurrence. It’s recommended you perform treatment nearing the end of the grazing season when worms are at their peak.
Bot treatments are also essential; ivermectin & moxidectin are the only available medications for horses with bots. I recommend AbIver™ along with the manual removal of the yellow bot eggs from the horse’s coat. AbIver Plus™ contains both ivermectin and praziquantel which is for treating tapeworm.
Deworming foals and weanlings
During the first year of life a foal should be dewormed at least 4 times. The first at 2-3 months to ensure against large roundworms. The second worming should be just before weaning ~6 months. At weaning, a FEC is a good idea to determine which worms need to be treated against. Third and fourth treatments should be between 9-12 months old and should target strongyles. Tapeworm treatment should be included around this time as well.
Remember that each horse and region is unique. Please consult with your local veterinarian for a more individualised treatment program for your horse.
Read part 1 to discover common species of equine worms
Read part 3 to discover common myths about worming