Description AniHist is an oral antihistamine and expectorant granule for use in horses, blended in a palatable base. Relief for “heavey” horses Relief of “barn” cough Great for seasonal allergies Oral antihistamine and expectorant granule. Feed 1/2 ounce per 1,000 pounds of body weight. Guaifenesin, USP 2400mg, Pyrilamine Maleate, USP 600mg