Horse Worms: Types, Symptoms, and the Best Deworming Practices
Worm infestations in horses are more common than many owners realize. Even horses that appear healthy can carry internal parasites that slowly affect their well-being. If not managed properly, these parasites can lead to serious health issues. Understanding the different types of worms, spotting early signs, and following the best deworming routine are key parts of responsible horse care.
This guide covers everything horse owners need to know to stay ahead of worm problemsāfrom redworms to the best deworming practices available.
Why Worm Control Is So Important
Internal parasites can harm a horse from the inside out. They steal nutrients, damage organs, and affect how a horse digests food. Some types can even lead to colic or weight loss that doesn't improve with better feeding.
Worms can be silent threats. Often, symptoms appear only after the infestation has caused enough damage. Thatās why regular parasite control isnāt optionalāitās a core part of good horse management.
Types of Worms Common in Horses
Here are the main worms that affect horses, along with what they do and how they impact health.
Small Strongyles (Redworms)
Also called redworms, small strongyles are one of the most dangerous and widespread parasites in adult horses. They can encyst in the gut wall and lie dormant for months before emerging all at once, causing inflammation and digestive upset. Moxidectin and a 5-day fenbendazole treatment are most effective against encysted larvae.
Large Strongyles (Bloodworms)
These parasites can migrate through blood vessels and cause severe internal damage. Though less common today thanks to modern dewormers, theyāre still a risk if left unchecked.
Roundworms are more common in foals and younger horses. They can cause respiratory issues, poor growth, and even intestinal blockages. Regular deworming early in life is crucial to prevent heavy infestations.
Tapeworms attach at the junction of the small and large intestine and often go unnoticed. However, they can cause colic, poor digestion, and weight issues. Praziquantel-based dewormers are typically used in fall or spring to target these parasites.
Bot fly larvae can be found in the horse's stomach after being ingested from eggs laid on the skin. They donāt always show symptoms, but a heavy load can cause stomach irritation. Ivermectin and moxidectin both work against bots.
How to Spot Worms in Horses
Not all horses show obvious signs of worms. Still, these symptoms are commonly associated with parasite infestations:
Sudden or unexplained weight loss
Diarrhea or frequent mild colic
Pot-bellied look, especially in young horses
Scratching the tail or rubbing hindquarters
Lethargy or reduced performance
Poor appetite or inconsistent eating habits
Coughing in foals or young horses (due to migrating roundworms)
If your horse is showing one or more of these signs, itās time to take a closer lookāand likely, a fecal test.
Deworming Practices That Work
Deworming isnāt just about giving a paste every few months. Todayās approach is smarter and more targeted.
Start with a Fecal Egg Count (FEC)
This simple test checks how many worm eggs are in your horseās manure. It helps you avoid unnecessary deworming and choose the right product. Many vets recommend doing FEC testing two to four times per year, depending on your horseās risk level.
Deworm Based on Age and Risk
Foals and yearlings need more frequent deworming due to their higher susceptibility Adult horses benefit from strategic deworming based on FEC results High-risk horses (those in crowded fields or with past worm problems) may need a stricter schedule
Rotational deworming used to be the norm, but it's no longer recommended without FEC data. Overuse of dewormers contributes to resistance, making treatments less effective over time.
What Dewormers Treat Which Worms
Here's a breakdown of commonly used dewormers and what they target:
Dewormer Effective Against
Ivermectin Bots, strongyles, roundworms
Moxidectin Encysted small strongyles, bots
Fenbendazole (5-day) Encysted redworms, roundworms
Pyrantel (double dose) Adult strongyles, tapeworms
Praziquantel Tapeworms (used in combo formulas)
Top Picks Available Through Pet Supplies Online:
These trusted dewormers are often available from stores offering reliable pet care products and horse supplies online:
Eqvalan Oral Paste Horses (Ivermectin) ā Great for bots and strongyles
Panacur Equine Guard Horse Wormer (Fenbendazole) ā Ideal for encysted small redworms
Equest Gel Horse Wormer (Moxidectin) ā Long-lasting control, especially effective for larval stages
Strongid P Paste (Pyrantel Pamoate) ā Used in double doses for tapeworms
Equimax (Ivermectin + Praziquantel) ā Broad-spectrum treatment, includes tapeworm control
Always dose based on your horseās weight and follow label instructions carefully.
Prevent Worms Before They Start
Deworming is important, but prevention is just as critical. Here's how to reduce worm exposure:
Remove manure regularly from paddocks and stalls
Rotate pastures if possible
Donāt overstock pastures with too many horses
Use separate feeding and watering areas to prevent contamination
Keep feed clean and stored properly
Regularly groom your horse to remove bot eggs from legs and coat
Stick to a parasite control schedule advised by your vet
What About Dewormer Resistance?
Worms can become resistant to certain medications when horses are over-treated or treated incorrectly. Thatās why using FEC results and choosing the right dewormer at the right time is so important. Only deworm when needed, and use the correct dose based on your horseās weight.
Worm control isnāt just about reacting to problemsāitās about preventing them. By understanding the types of worms, recognizing signs early, and following a smart deworming plan, you can keep your horse in top shape.
Look for reliable pet supplies online that offer a wide range of parasite treatments and dewormers. Choose products that are effective, easy to administer, and suited to your horseās specific needs.
If in doubt, your vet can help guide you through creating a deworming plan that works best for your horse, the environment, and your routine.
