How Often Should You Worm Your Horse in New Zealand?

Worming your horse is one of the most important routines for maintaining long-term health and performance. Internal parasites can cause everything from weight loss and dull coat to more serious issues like colic, poor nutrient absorption, and overall decline in condition. In New Zealand, where horses often graze on pasture year-round, a proactive worming program is essential.

But how often should you worm your horse in NZ, and what products work best? This guide breaks down everything you need to know — from seasonal timing and parasite types to recommended horse wormers and product suggestions.

🧬 Why Horses Need Regular Worming

Horses are natural grazers and constantly exposed to parasite eggs and larvae on paddocks, especially in wetter, warmer months. The most common internal parasites in New Zealand include:

• Large strongyles (bloodworms)

• Small strongyles (cyathostomins)

• Ascarids (roundworms)

• Tapeworms

• Bots

Left untreated, these parasites can cause poor condition, colic, diarrhoea, anaemia, and performance issues — particularly in foals, young horses, or older animals.

📅 How Often Should You Worm Your Horse in NZ?

There’s no one-size-fits-all answer. How often you should worm depends on:

• Age of your horse

• Grazing environment (shared paddocks vs. solo)

• Manure management

• Seasonal climate

• Past worming history

• Faecal egg count testing (FEC)

Here’s a general guideline:

For adult horses, faecal egg count testing is recommended at least twice a year to determine whether worming is even necessary — over-worming can lead to resistance.

🌦️ Seasonal Worming for NZ Climates

In New Zealand, pasture-based grazing systems mean worms are active year-round, but particularly problematic in:

• Spring (Sep–Nov): Increased egg laying and larvae activity as weather warms

• Summer (Dec–Feb): Bots and strongyles more common

• Autumn (Mar–May): Time to treat for tapeworms and bots before winter

• Winter (Jun–Aug): Fewer parasites active, but still important to manage

🧪 Choosing the Right Wormer

When selecting a wormer, it’s crucial to rotate active ingredients, not just brand names. Look for products containing:

• Ivermectin – effective against bots, strongyles, roundworms

• Moxidectin – similar to ivermectin, longer acting

• Praziquantel – needed for tapeworm control

• Oxibendazole/Pyrantel – older actives, sometimes milder

🛒 Recommended Horse Wormers on Pet Supply

✅ Equimax LV Horse Wormer

A powerful broad-spectrum paste wormer containing Ivermectin + Praziquantel, making it highly effective against roundworms, bots, and tapeworms. Suitable for horses of all ages and a top seller across NZ.

✅ Equest Plus Tape Gel (11.8g)

Contains Moxidectin + Praziquantel and offers long-lasting protection. Great for reducing how often you need to worm — lasts up to 13 weeks!

🔁 Wormer Rotation: Why It Matters

Using the same active ingredient every time increases the risk of resistance, meaning parasites adapt and survive future treatments. To combat this, rotate between different wormer types across the year (e.g., Ivermectin → Moxidectin → Oxibendazole).

🐎 Special Considerations

• Foals and Pregnant Mares: Always check the label. Not all wormers are safe for young or pregnant horses.

• Miniatures/Ponies: Dose according to weight. Overdosing small breeds is a common issue.

• Performance Horses: Stay on top of worming to avoid any drop in energy or condition.

📝 Final Thoughts

Worming your horse in New Zealand requires more than just a calendar reminder — it’s about tailoring your approach based on the horse’s age, environment, and the seasons. Using quality products like Equimax, Equest, and Ammo from trusted suppliers ensures your horse stays healthy and protected.

Need help choosing the right wormer? Browse our full equine health collection or reach out to our team for expert guidance.