Complete Guide to Worming Your Horse for Best Health

Good health is vital for your horse to perform and feel settled. A well-planned worming programme is essential to keep your equine healthy by preventing harmful parasitic infestations. Horses have delicate digestive systems that can easily host a range of internal parasites, making regular and targeted worming a key part of responsible horse ownership. Always plan your worming strategy in consultation with a vet to ensure it suits your horse’s environment and health.

Understanding Types of Worms Affecting Horses

Parasites in horses vary widely, each with distinct impacts and treatment approaches. Here are the main types you should be aware of:

Bots

Bots are larvae from the bot fly that attach inside the horse’s stomach, causing inflammation and discomfort. They are best controlled by specific anthelmintics during appropriate seasons.

Hairworms

Hairworms inhabit the stomach and can affect multiple livestock species, including horses and ruminants like sheep and cattle, necessitating vigilant control measures.

Ascarids

Common in young horses, heavy ascarid infestations manifest in coughing, nasal discharge, and colic symptoms, requiring careful early-life worming protocols.

Threadworm

Typically affecting foals under six months and transmitted through the mare’s milk, threadworms require targeted treatments available in the UK.

Tapeworm

The tapeworm lives in the small intestine and caecum, attaching to the stomach lining and causing ulcers and potentially serious colic. Appropriate wormers containing praziquantel are necessary for effective control.

Large Strongyles

Large strongyles are dangerous parasites that can damage arteries and cause blood clots, leading to significant health decline marked by anaemia and weight loss.

Small Strongyles (Small Red Worms)

Infiltrating the intestinal wall, small strongyles create cysts that can suddenly release larval masses causing ulcers, bleeding, loose stools and colic, demanding a proactive worming approach.

Pinworm

Pinworms commonly cause irritation and itching around the anus but are generally less severe. Routine worming helps manage these.

Lungworm

Mostly infecting donkeys, horses can acquire lungworm by sharing pasture, sometimes without immediate respiratory signs. Early detection and treatment aid in preventing respiratory disease escalation in ageing horses.

Methods of Worm Control: Medication and Pasture Management

Effective worm control combines medicinal and environmental practices:

• Anthelmintics: Various classes are used to target different parasites, including benzimidazoles (fenbendazole, mebendazole), tetrahydropyrimidines (pyrantel), macrocyclic lactones (ivermectin, moxidectin), and praziquantel-based wormers for tapeworms.
• Rotate Wormers: To avoid resistance, alternate wormers with different active ingredients rather than just brands. This ensures efficacy over time.
• Pasture Management: Regularly remove manure and rotate grazing areas to reduce parasite load in the environment, a vital supplement to chemical treatments.

Developing an Effective Worming Programme: Rotational and Tactical Approaches

The UK climate with its damp summers and milder winters favours parasites, making a considered worming plan indispensable. Consult your vet to tailor your programme.

Rotational Worming: Use different classes of chemicals in rotation during grazing seasons to cover a broad parasite spectrum. Choose from:

• Macrocyclic Lactones - ivermectin, moxidectin
• Tetrahydropyrimidines - pyrantel
• Benzimidazoles - fenbendazole, mebendazole, oxibendazole

Products combining praziquantel with these groups address tapeworms alongside routine worming.

Tactical Worming: Worm during periods when specific parasites are most prevalent. For example, treat for bots and small redworms in winter, tapeworm in summer, and target strongyles during grazing periods.

Targeted Worming with Testing: A modern approach involves performing faecal egg counts to determine actual parasite burdens before worming. This prevents unnecessary treatments and reduces chemical exposure, saving costs and slowing resistance development. Kits are easily available and simple to use following product instructions.

Health and Environmental Considerations for Worming

When planning worming:

• Accurately weigh your horse using a weight tape or weighbridge. Underdosing risks ineffective treatment and resistance.
• Adjust worming products for foals or young horses, using formulations suitable for their age and health status.
• Consider the local environment. If your horse has access to aquatic environments, stable during treatment and for two to three days after to prevent chemical runoff harming wildlife.
• Store wormers securely and keep pets and children away as some ingredients can be dangerous, especially for dogs like Border Collies.

Step-By-Step Guide to Worming Your Horse

Step 1: Preparation

• Weigh your horse accurately and consult your vet to select the appropriate wormer and dosage.
• Choose a calm, quiet location and have a headcollar and lead rope ready.
• Read the instructions of the wormer carefully.

Step 2: Administering Wormer

• Fit the headcollar and gently lead your horse to the prepared location.
• Stand on the near side (left side) and hold your horse’s head steady.
• Insert the syringe into the corner of the mouth and depress the plunger slowly to administer the wormer.
• Hold the horse's head raised slightly for a few seconds to encourage swallowing.

Step 3: Aftercare

• Stable your horse for 48 hours if possible to reduce pasture contamination risk.
• Wash your hands thoroughly after treatment and secure worming products.
• Observe your horse for any adverse reactions.

Step 4: Monitor and Plan

• Keep a worming diary to track treatments and schedules.
• Consider periodic faecal egg count testing to tailor future worming needs.
• Maintain good pasture management practices.

Common Questions About Worming Your Horse

How often should I worm my horse?

Quick Answer: Frequency depends on your horse’s age, environment, and faecal egg counts, but typically 4-6 times annually with targeted timings is effective.

Regular worming is essential but overly frequent treatments can encourage resistance. Tailor your plan with your vet based on testing and seasonal parasite patterns.

Can I treat my horse myself?

Quick Answer: Yes, with proper knowledge, equipment, and vet guidance, owners can administer wormers safely.

Owner administration is common, but it’s important to be well-informed about dosing and worm types to avoid under or overdosing. Your vet can provide instruction and advice.

What if my horse resists worming?

Quick Answer: Practice with syringes filled with tasty liquids and calmly build your horse’s tolerance.

Stress can make worming challenging. Using positive reinforcement techniques such as offering apple sauce can help your horse accept treatment more willingly.

Why is pasture management important?

Quick Answer: Managing manure and rotating grazing reduce worm larvae, helping minimise parasite exposure and complementing chemical worming.

Pasture management is a natural, chemical-free way to lower parasite load and sustain your horse’s health long term. It reduces contamination and breaks the parasite life cycle.

Conclusion

Worming your horse is a vital, ongoing aspect of responsible care. Combining a vet-informed, targeted worming schedule with pasture management ensures your horse remains healthy and comfortable. Accurate dosing, seasonal timing, and faecal testing are key to success, alongside environmental considerations to protect surrounding wildlife. With careful attention and compassion, you can maintain your horse’s well-being and enjoy many happy years together.