Styptic powder is a handy first-aid tool used to stop bleeding in dogs. Most commercially available styptic powders contain an ingredient called ferric subsulfate, which helps promote blood clotting by constricting blood vessels when applied to a bleeding nail or minor wound. It aids in quickly stopping bleeding and can prevent excessive blood loss. Ferric sulfate has not been approved by the FDA as being either safe or effective. Alternatively, look for natural and organic options to stop bleeding and encourage healing.