Worm infestations in equines are very common. All horses and ponies are at risk of worm infections; in fact, most horses carry some degree of worm burden (infection) throughout their lives, but most do so without developing clinical signs of disease. A high burden of parasitic worms however, can cause serious health problems if left untreated.

The life cycle of most worms incorporates stages on the pasture (eggs and larvae); horses typically become infected by ingesting the eggs or larvae while grazing. After ingesting the eggs or larvae, these develop into adults in the digestive tract or other organs of the horse and eventually produce eggs that can be shed in the environment through the feces, potentially infecting other horses.

Common symptoms of worm infections in horses include:

• Weight loss
• Colic
• Diarrhea or constipation
• Rough hair coat
• Poor growth in foals
• Respiratory problems 
• Pot-bellied appearance

In general, young horses have less natural immunity to worms than older horses, so they tend to carry higher parasite burdens and can contribute more eggs to pastures. Older horses and those that are stabled continuously are unlikely to pick up many parasites since the worms are unable to complete their life cycle.¹ However, even short periods of grazing can lead to infection, so it should never be assumed that a horse is free of worms.

Mitigating worm infestations in equine facilities can be effectively achieved through a targeted worming program that addresses treating horses with the right wormer at the right time of year.

Ivermectin + Fenbendazole for Worms in Horses

Ivermectin is a drug mixture of two structurally semisynthetic lactones that is used in veterinary medicine as an anthelmintic, boticide, acaricide, and insecticide. Ivermectin has a broad spectrum of activity against intestinal and insect parasites, and kills migrating larvae.² It is used in dogs and cats to prevent heartworm disease by eliminating tissue stages of heartworm larvae, as well as in cats to remove and control hookworms.³

Used in horses, cattle, and sheep as a broad-spectrum ecto- and endoparasiticide, it is also used as an antiparasiticide in a variety of other species. Ivermectin is widely prescribed by veterinarians in all horse deworming programs because of its efficacy. 

Ivermectin is known to provide effective broad spectrum control of bots, habronema, ascarids, strongyles, thread worms, pinworms, tape worms, lung worms, and is also effective against the filaria of Onchocerca, larvae of habronema, and arterial larvae stages of strongyles.²

Fenbendazole is a broad spectrum anthelmintic that is used to control a number of common equine parasites, including large strongyles (Strongylus edentatus, S. equinus, S. vulgaris), encysted early third stage (hypobiotic), late third stage and fourth stage cyathostome larvae, small strongyles, pinworms (Oxyuris equi), ascarids (Parascaris equorum), and arteritis caused by fourth stage larvae of Strongylus vulgaris.²

Fenbendazole is considered to be an extremely safe wormer by veterinarians. According to the available literature, it is able to withstand overdoses of 100-200 times the standard dose without causing harm to the horse. For this reason, fenbendazole is often used to clear immature parasites, which are often resistant to worming medications due to their slower metabolism.

Where to buy Ivermectin + Fenbendazole

Ivermectin + Fenbendazole is available in the U.S. through several pharmaceutical manufacturers and through veterinary custom compounding companies. 

Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

¹Nielsen, M., et. al. Handbook of Equine Parasite Control, Second Edition. March 2018, John Wiley & Sons, Inc.

²equimed.com.
³equimed.com.