Equine Deworming Letter

Changes in Equine De-Worming Protocol

Equine internal parasites are silent killers, they can cause extensive internal damage, and as a horse owner you may not even realize your horses are infected. Parasites can lower immune system ability, rob the horse of valuable nutrients, cause gastrointestinal irritation and unthriftiness.  At their worst they can lead to colic, intestinal ruptures and death. These facts are not new to horse owners but some of the currently accepted concepts about deworming are proving to have limitations. The rotational deworming programs that have been the gold standard for years are creating worm resistance to several classes of dewormers. The undiagnosed use of dewormers at random intervals, and deworming horses who do not need it, can lead to resistance making our current dewormers less and less effective. Resistance has been documented to all of the current dewormers in 21 countries. There has even been resistance documented to Ivermectin and Quest, which were first introduced in the 80's and 90's respectfully. There are no new compounds in development so we are faced with trying to protect our horses with what is available. In a few more years these dewormers could become ineffective. The best management practices are shifting the emphasis from herd deworming to diagnosing the individual horse. This allows identification of the horses that carry the heaviest parasitic burdens, and treat them accordingly. Eighty percent of the worm burden is carried by twenty percent of the horses. It will vary from herd to herd but with a strategic deworming plan most horse owners can deworm up to 78% less and still maintain a healthy herd.

Strategic deworming is one component of a program that is aimed at decreasing the total number of infective parasites in the environment. The most useful tool in strategic deworming is a fecal egg count reported as egg per gram (epg). This number correlates to the number of adult worms in the horse. A horse with a large worm burden will start to show clinical signs at some point, by utilizing fecal egg counts we can determine which horses need to be dewormed and which do not. This eliminates the guesswork on which program to use, what dewormer to use, and when is the best time to deworm? The effectiveness of the current dewormers will be preserved for future generations of horses.

If you have any questions or need any further info, please contact us at Montezuma Veterinary Clinic (MVC). September and October are Equine Parasite months at MVC and we encourage you to bring in a fresh fecal sample from each horse you own to determine their level of infestation and receive a consultation on a deworming program. We have developed a cost effective program for clients to test all of their horses.

The Team at Montezuma Veterinary Clinic