Orally—Glycerin lubricates the throat of the horse. Sometimes it is mixed with Peppermint oil adding the aromatic and possibly the decongestant quality of the peppermint oil. Peppermint is also known to soothe the stomach and help in ulcer situations—horses usually love peppermint. Often when the weather is real cold or if it has been extremely dry many people will administer glycerin orally prior to exercise to aid in lubricating the throat whether it has peppermint added or not. We recommend 1 ounce or 30 cc per dose. I think you can easily give 2 doses in a morning if you so desired, but for the most part, a dose is considered 1 ounce.
If your horse has suffered from a cold or allergies, then Glycerin and glycerin & Peppermint mix will not work to reduce mucus like Wind Aid will. But, you will notice Wind Aid is in a Glycerin base for the lubricating quality glycerin gives. It has peppermint and eucalyptus oil for the properties they contribute and potassium iodide, which acts like an expectorant and aids in reducing or eliminating mucus. The potassium iodide is what sets Wind Aid apart from the others. In Canada, they often just grab for the Glycerin prior to exercise, and this is fine but “in my opinion,” if I had a quart of each in my tack room, I would definitely go for the Wind Aid over just Glycerin.
The second use for Glycerin in the barn is using it mixed with other topical. For instance, I mix ½ Choate’s liniment, ¼ Witch Hazel and ¼ Glycerin as a beginner's leg brace. The glycerin tames the Choate’s down and makes it a moisturizing brace. I also mix glycerin with Doc’s leg paint. Right now, while Thurben is on vacation, he is getting his legs painted with a mix of glycerin and Doc’s. The glycerin will help to add a moisturizer to the Doc’s so it doesn’t blister as easily but lets the Doc’s work as a counterirritant bringing blood to the area and hopefully healing any minor issues he may have had at the end of the meet. Some People use glycerin to sweat a neck or legs and this will work fine; Glycerin is an excellent choice because it washes off with water and it is hypoallergenic and moisturizing.