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 sooth 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 easy 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 and 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. I know up 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.