You’re standing in the tack room with two printed deworming schedules from well-meaning barn friends, and they contradict each other line by line. One says “every 8 weeks no matter what.” The other says “never deworm without a fecal.” If you want evidence instead of opinions, start here: deworming is no longer a calendar ritual. It’s a test-and-treat system.
The old frequent-rotation model was built when resistance was less of a problem. Now, routine blind dosing can select for resistant parasites, waste money, and still leave your horse exposed at the wrong times. A modern plan starts with fecal egg count (FEC) data, then uses your horse’s shedding pattern, age, turnout conditions, and travel exposure to decide when and what to treat. You are not “doing less”; you are doing it with better aim.
An FEC reports eggs per gram (EPG), usually for strongyle-type eggs in adult horses. Most practices classify adult horses roughly as low shedders under 200 EPG, moderate around 200–500 EPG, and high above 500 EPG. Your clinic may use slightly different cutoffs, but the principle is the same: horses in the same pasture can have very different shedding levels. That is why one-size-fits-all barn schedules fail. Your horse’s risk is not your neighbor horse’s risk.
Sample quality matters more than owners realize. Collect fresh manure—ideally within a few hours—place 2–4 fecal balls in a clean bag, push out extra air, label with horse name/date/time, and keep it cool until drop-off. Don’t leave it in a hot car and don’t freeze it. Poor sample handling creates unreliable counts, and unreliable counts create bad treatment decisions. If your horse is due for routine care, ask your vet to pair the FEC with a broader parasite plan instead of treating based on one number in isolation.
Timing should follow local parasite pressure and management reality. In many regions, spring and fall are key reassessment points for adults, with additional checks depending on stocking density, manure removal, and pasture hygiene. Young horses usually need closer supervision than healthy adults because their parasite profile and immunity are different. Horses that travel often, rotate through shared grounds, or live in high-traffic boarding setups may need more frequent review than a low-exposure horse at home.
Product choice should be intentional, not based on brand familiarity or what is on sale. Different drug classes target different parasite groups and have different resistance patterns on different farms. Your vet should select the product based on current findings and farm history, not habit. Randomly rotating products “just in case” feels proactive but can be the opposite if resistance is already present. Treating the wrong target at the wrong time is still mistreatment, even when done on schedule.
One step many owners skip is confirming that treatment worked. Ask your vet about a fecal egg count reduction test (FECRT): pre-treatment FEC, treat, then recheck in the recommended interval for that drug class (often around 10–14 days for some products). If reduction is poor, that’s actionable information—possible resistance, dosing error, or strategy mismatch. Without follow-up, owners can keep using ineffective products for years while believing they are protected.
Dosing accuracy is a major failure point. Underdosing encourages resistance and poor control. Use a weight tape at minimum, and a scale when available, then set the syringe to real body weight, not wishful weight. Administer so the horse actually swallows it; paste on the lips or floor is not a completed dose. If your horse is hard to dose safely, ask your vet or trainer for handling protocol rather than repeating failed attempts and guessing what went in.
Also, don’t blame every symptom on worms. Tail rubbing can come from skin irritation, pinworms, sweet itch, or hygiene issues. Weight loss can be dental, ulcers, pain, or metabolic disease. Intermittent loose manure has a long differential list. Parasites may be part of the picture, but blanket deworming in response to every symptom can delay real diagnosis. If signs are persistent or your horse is unwell, call your vet for a full workup, not just a tube from the shelf.
If you want a plan you can trust, ask your vet for a written 12-month parasite strategy with test dates, treatment thresholds, and follow-up criteria. Put those dates in your phone now. In the barn, when competing opinions get loud, remember this line: test first, treat with purpose, then prove it worked.
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