Anthracite EQ Paste Oxibendazole Horse Dewormer is a broad-spectrum dewormer that helps to control many internal parasites to keep your equine partner healthy. The active ingredient, oxibendazole, helps to remove and control large roundworms, pinworms, large strongyles, small strongyles, and threadworms. It’s also been effective against strongyles that are resistant to benzimidazole-based products. One syringe treats horses weighing up to 1,200 pounds, and the oral paste is convenient to administer.