Understanding Horse Dewormers: Essential for Your Equine's Health
- Jun 15
- 4 min read
Updated: Jul 16
Horse dewormers are vital for maintaining equine health. They help protect horses from internal parasites that can cause serious health problems. In this blog post, we will explore the different types of dewormers available and their effectiveness in combating various parasites.
When we were in the Outback observing brumbies, unchecked intestinal parasite burdens were among the leading causes of death. (Brumbies in Central Australia die in long, protracted, horrible ways. We romanticise their lives, but the reality is quite an eye-opener.)
Due to these reasons, regular deworming is crucial. So, we often hear that we must rotate our dewormers. But how do we determine which dewormer to use at the right time?
Common Intestinal Parasites in Australian Horses
Horses in Australia can face several internal parasites. Understanding these can help you select the right deworming strategy:
Large Strongyles (Bloodworms): Once common but now rare, thanks to effective deworming practices.
Small Strongyles (Cyathostomes): These encyst in the intestinal walls and may lead to colic.
Roundworms (Ascarids): Mostly affect young horses, potentially causing lung damage and intestinal blockages.
Tapeworms: Can contribute to colic and digestive issues.
Pinworms: Cause tail rubbing and irritation in horses.
There are additional parasites outside of the intestines that horse owners should be aware of. If you missed the article on neck threadworm, you can read that here.
Types of Dewormers
Different dewormers target various parasites in distinct ways. Here's an overview:
1. Benzimidazoles (e.g., Fenbendazole, Oxibendazole)
How they work: These disrupt the parasites’ metabolism, preventing nutrient absorption.
Effective against: Roundworms, some strongyles, and pinworms.
Usage: Often utilized in rotation or as a power pack treatment, such as a five-day regimen (e.g., Panacur) for encysted small strongyles.
2. Tetrahydropyrimidines (e.g., Pyrantel Pamoate, Pyrantel Tartrate)
How they work: They paralyze parasites, allowing them to be expelled via the digestive system.
Effective against: Roundworms, pinworms, and some strongyles.
Usage: Generally administered as a paste or pellet mixed in feed.
3. Macrocyclic Lactones (e.g., Ivermectin, Moxidectin)
How they work: These disrupt nerve functions in parasites, resulting in paralysis and death.
Effective against: Strongyles, bots, lungworms, and some migrating larvae.
Usage: Provide broad-spectrum protection; Moxidectin is particularly effective against encysted strongyles.
4. Isoquinolones (e.g., Praziquantel)
How they work: They damage the outer membrane of parasites, making them vulnerable to destruction.
Effective against: Tapeworms.
Usage: Frequently combined with Ivermectin or Moxidectin for comprehensive parasite control.
There’s also a growing body of research supporting the efficacy of benzimidazoles and ivermectin in late-stage cancer treatments for humans. It’s surprising that this hasn’t received more media attention!
Paste-Based Dewormers
Below are some popular paste-based dewormers and their uses:
Equimax: Ivermectin and Praziquantel. Broad-spectrum, including tapeworms.
Equest Plus Tape: Moxidectin and Praziquantel. Targets encysted strongyles, bots, and tapeworms.
Strategy-T: Oxfendazole and Pyrantel. Effective against roundworms, strongyles, and tapeworms.
Ammo Allwormer: Abamectin and Praziquantel. Covers bots, strongyles, and tapeworms.
Panacur 5-Day: Fenbendazole. For encysted small strongyles.
Equimec Plus Tape: Ivermectin and Praziquantel. Works on bots, strongyles, and tapeworms.
Equitak Excel: Abamectin, Oxfendazole, and Praziquantel. Broad-spectrum, including tapeworms.
Ultimum Long Acting: Moxidectin. Provides long-lasting control over strongyles and bots.
Pelleted Dewormers
Pelleted or powdered dewormers are also available. Here are some notable options:
Eraquell Pellets: Ivermectin–Targets bots, strongyles, roundworms, pinworms, and lungworms.
Strategy-T: Oxfendazole and Pyrantel–Focuses on roundworms, strongyles, and tapeworms.
Ammo Allwormer: Abamectin and Praziquantel–Covers bots, strongyles, and tapeworms.
The Challenge of Dewormer Resistance
Dewormer resistance has become a significant issue in equine health. When horse owners regularly use these medications, only the parasites that are vulnerable to the drug die. The remaining population continues to reproduce and passes on their resistance to future generations.
Signs of Dewormer Resistance
Be on the lookout for the following symptoms:
Persistent Parasite Presence: High fecal egg counts despite regular deworming suggest parasite survival.
Recurrent Colic Episodes: Strongyles can cause digestive distress, leading to frequent colic.
Unexplained Weight Loss: A horse losing weight despite proper nutrition may have a high parasite load.
Lethargy or Poor Performance: A sluggish horse might be struggling with internal parasites.
Excessive Tail Rubbing or Itching: Pinworms cause irritation around the anus, leading to excessive rubbing.
Swelling: Localized swelling may occur in areas like the belly or jaw due to migrating parasites.
A Holistic Deworming Strategy
Fecal Egg Count Testing is pivotal. Regular testing helps determine the efficacy of your dewormers. You can send manure samples for testing or conduct tests yourself. It’s straightforward and requires a McMaster slide and a microscope. These are readily available online.
Strategic Deworming
To manage resistance, avoid overusing dewormers. Instead of deworming every six weeks, aim for seasonal deworming. At Sound Advice, we typically deworm our horses in April and August, employing a range of practices to manage parasites.
We utilize a combination of moxidectin and praziquantel to combat encysted strongyles, bots, and tapeworms. If our horses exhibit signs of pinworm infestation, we will use a benzimidazole that also targets roundworms.
Additional Management Strategies
To reduce parasite exposure, consider the following:
Collect and compost manure regularly.
Rotate grazing areas to prevent infestations.
Harrow pastures to expose parasite eggs to sunlight.
Feed horses whole oats to attract birds that help break down manure.
Conclusion
In summary, no single deworming plan is suitable for every situation. The essential takeaway is that indiscriminate and frequent deworming contributes to resistance in parasites. We currently lack a universal solution to address these resistant parasites.
Not even pumpkin seeds offer a guaranteed remedy, although there’s some promising research on that. By conducting fecal egg counts, you can assess the worm burden in each horse and apply the most effective dewormer for their specific needs.
Ultimately, dewormers disrupt the gut micro-biome. We offer a prebiotic/probiotic combo designed for overall gut health, at just 10g/day. One bag lasts for 100 days, representing a small investment in your horse’s health.
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