Information gained by USESR volunteer, Janice Palmer of McKinney, Texas:

Texas A&M recommends worming your horse once every four months. You may need to worm more often, depending on the area you live in or the conditions in which your horse is kept. For instance, if your horse is on a pasture where there are a lot of horses and they have a higher risk of doing a lot of grazing where there is a high amount of manure in the area, you will probably want to worm at least five times a year. You may also want to worm five times a year and do your extra worming during the rainy/warm season/month, a time when manure stays fresh longer and worms live longer inside the manure. Janice worms four times a year: January, March, August, and November.

Rotating wormers is important, too, because different wormers have different active ingredients and not all wormers kill all species of worms. Janice recommends rotating Ivermectin, Strongid, and Panacur/Safeguard. She says it is important to use the Panacur or Safeguard at least once in the spring because it is the most effective against Strongyles. Remember, Janice worms according to her own geographical area, near Dallas, Texas.

Janice's vet recommends she worm all of her mares with Ivermectin two weeks before they foal, so that the foal is born worm-free. Check with your own vet before you do this and always follow his/her instructions. As soon as Janice's foals begin to eat, she sets up a creep feeder for them that the mares can't get to. She gives the foals the daily pelleted wormer, Strongid C 2X in their feed every day. When they are about six months old, they begin to worm them with various pastes, using about 1/3 of a tube. Janice has found that this routine keeps her foals completely worm-free. They grow and gain weight better and they eat less feed because they utilize it better. You can discuss more about worming with Janice via .

To worm the starved horse, or any horse whose ribs are showing that you may have purchased/rescued from auction that you do not know it's history and have reason to doubt that it has been properly taken care of, or that you suspect may have a large worm infestation, worm the horse the first time with any mild wormer. Your feedstore representative will be able to direct you in this matter. Name brand is not important, as long as it is a mild wormer. In two weeks, worm the horse again with something stronger, such as Zimectrin or Equimectrin, the "generic" brand of Zimectrin. After that, go ahead and put the horse on a normal worming schedule, unless it has diarrhea. It has been our experience that diarrhea is an indication of a horse being wormy, even when ribs aren't showing and coat isn't particularly dull. When this happens, we worm the horse again with something mild, then follow up two weeks later with the stronger wormer, just to be safe.

Be very careful when using Quest Gel Wormer, manufactured by Ft. Dodge, makers of Premarin. Quest has killed many horses. USESR has no current statistics on this, but open this discussion on just about any horse-related e-mail list and you will get several testimonies of horses dying because of Quest Gel Wormer. Apparently, it is a very strong wormer and that is why it is so dangerous. Killing off large worm infestations too fast can kill the horse, which is why you always want to start out with a mild wormer and then step up to a stong one when worming a horse you suspect may have a large worm infestation. It should be noted, however, that many, many people use Quest Gel Wormer and never have a problem with it.

Ivermectin is the active ingredient in Zimectrin, Equimectrin, and Rotectin I. Fenbendazole is the active ingredient in Safeguard and Panacur. Pyrantel Pamoate is the active ingredient in Strongid and Rotectin II. When rotating wormers, do not accidentally use two in a row with the same active ingredient.