28/05/2026
🐴 Horse Worming: It’s Not Just When You Worm — It’s What You Use
Most horse owners follow the old rule of thumb: worm at the change of each season.
Autumn, winter, spring, summer — simple, routine, predictable.
But while that timing is broadly right, relying on seasonal rotation alone can leave gaps. Some parasites slip through, and over time, resistance can build.
As we move from autumn into winter, things on the farm slow down — pasture growth drops, temperatures cool, and horses seem quieter.
But parasite pressure doesn’t disappear. It simply shifts.
Some worms persist on pasture. Others sit inside the horse in different lifecycle stages. Even without obvious signs, a burden can still be ticking along in the background.
________________________________________
❄️ Which Worms Matter Through Autumn & Winter?
Small strongyles
One of the biggest concerns at this time of year.
During cooler months, they can sit encysted (dormant) in the gut wall. They may not cause immediate issues, but they can build up and emerge later, creating significant problems.
Roundworms
More common in younger horses, but still worth considering depending on your age groups and management.
Tapeworms
Different lifecycle entirely.
Horses pick them up by ingesting oribatid pasture mites — not directly from grazing.
Because their lifecycle is slower and more seasonal, tapeworm burdens tend to build gradually.
Autumn is a key time to target them.
________________________________________
🎯 Why Product Choice Matters
Different parasites require different actives. Using the wrong product at the wrong time can leave gaps — or drive resistance.
Encysted small strongyles
• Moxidectin
• Fenbendazole (specific programs)
Tapeworm
• Praziquantel
• Pyrantel (correct dose)
Roundworms
• Fenbendazole
• Pyrantel
Broad-spectrum control
Combination drenches are often used when multiple parasites need to be targeted at once.
________________________________________
🧴 Where iO Products Fit In
During the autumn–winter period, the focus is on managing existing burdens and targeting parasites that persist through cooler conditions.
Products such as:
• iO Fenbender
• iO Equiduo Liquid
• iO Blade
…contain actives suited to targeting common parasites at this time of year and can play a role within a broader, seasonally aware worming program.
________________________________________
🧪 Smart Worming = Product Choice + Timing + Evidence
Your worming plan should be guided by:
• Faecal egg counts
• Seasonal conditions
• Age groups and risk factors
• Your overall worming strategy
If you need tailored advice, consult your local veterinarian or speak with our team.
________________________________________