Can You Give a Miniature Horse Too Much Wormer?

Horse wormer is designed to be given to a horse in doses based on the horse's weight. According to the American Miniature Horse Association, the average miniature horse weighs between 150 and 200 lbs. The average adult full-sized horse weighs close to 1000 lbs. If a miniature horse receives a wormer dose for a full-sized horse, it is receiving five times the amount of wormer it should. Wormer overdose can have varying effects depending on the type of chemicals in the wormer.

  1. Fenbendazole-Based Wormers

    • Fenbendazole-based wormers are considered to be the safest of the wormers. Healthy horses can receive 100-200 times the standard dose without being seriously harmed. Safe-Guard is a fenbendazole wormer.

    Oxibendazole- and Ivermectin-Based Wormers

    • Oxibendazole- and Ivermectin-based wormers are effective against a variety of worms and can be given at up to 60 times the recommended dose without seriously harming a healthy horse. A commonly used Oxibendazole wormer is Anthelcide EQ, while Zimecterin, Equimectrin and Ivermectin are common Ivermectin-based wormers.

    Pyrantel Pamoate-based Wormers

    • Pyrantel pamoate-based wormers are safe at up to 20 times the recommended dose. Strongid and Exodus contain pyrantel pamoate.

    Moxidectin-Based Wormers

    • Moxidectin-Based Wormers have been the topic of much debate because these products can severely harm or kill a healthy adult horse at five times the recommended dose. The typical tube contains at least enough wormer to treat a 1,200 lb horse, which would translate into eight times the correct dosage for a 150 lb miniature horse and would likely prove fatal. Quest is a moxidectin wormer.