Inland Equine Veterinary Service

11803 S. Sherman Rd.
Spokane, WA 99224


Small Size...Big Punch

Horses GrazingInternal parasites have long been labeled ‘silent killers’. Much of the time extensive internal damage is occurring without owners even being aware their horses are infected. Consequences of parasitic infection included: robbing your horse of vital nutrients, causing gastrointestinal irritation, unthriftiness, colic, intestinal rupture, and even death.

Decreasing your horses risk from intestinal parasites is a multifactorial process. There are a variety of deworming programs available to your horse including daily deworming and rotational deworming systems. Determining the correct deworming program for your horse is based on a variety of factors such as susceptibility of your horse to parasitism, response to treatment, and farm management.

Daily dewormers work by providing a small amount of dewormer daily to prevent new parasitic infections. They do not however resolve existing infections or kill bots, thus traditional paste dewormers must still be used periodically.

In a rotational deworming system, horses are dewormed one to three months apart depending on your specific horse’s needs. The anti-parasitic agent used varies depending on time of year and specific parasite control. Starting at the first frost an ivermectin product should be used to kill bots, ascarids, nematodes, and small strongyles. Praziquantel and fenbendazole products are then worked into the rotational system. Praziquantel is effective at killing tapeworms, and fenbendazole is used to kill large and small strongyles and ascarids.

In addition to the administration of deworming products, farm management can go a long way in increasing the effectiveness of any deworming programs. Good management practices include: monitoring fecal egg counts, grouping horses of like ages together, rotating pastures, removing manure from paddocks, stalls, and pastures, and not feeding on the ground. If you have questions or concerns about your current deworming program, please contact the veterinarians at Inland Equine Veterinary Service to help you formulate a plan that meets the needs of your specific horses.