Straight from the Horse's Mouth

Samantha Enslen, Writing for
2-minute read

straight from the horse's mouth

Have you ever wanted to hear something straight from the horse’s mouth?

If so, you’ve wanted the honest truth from the original source.

Maybe you heard that your best friend was fighting with her boyfriend. Could be true. But you’re not satisfied with a rumor. You want to hear the story directly from her—straight from the horse’s mouth.

But how is your friend like a horse? And why are we looking in her mouth? 

It’s because one of the most ancient ways of knowing a horse’s age is by looking at its teeth. You see, horses’ teeth emerge—and then deteriorate—in a very predictable pattern

When horses are born, their teeth are buried in their gums. Within eight days, their baby teeth, also called milk teeth, start to come in. By age one, all 24 of the milk teeth are in place. 

Over the next five years, those milk teeth are shed and replaced with permanent teeth. Then, the edges of those teeth are slowly worn away as the horse grinds grass day after day. By age eight, the teeth are so worn down that a “dental star” appears—the dark core of the tooth, finally exposed to the light of day.

At age 10, a brownish groove appears in the horse’s upper corner incisors. The groove extends farther and farther down the tooth until the horse hits 20. Then it begins to slowly disappear and is gone by age 30. 

All these changes are highly predictable. So by looking at a horse’s teeth, you can make a reasonable guess at its age.

In contrast, looking at your friend’s teeth won’t tell you jack squat about her boyfriend. But at least she’ll know that you’re coming to her for the truth.

That’s your tidbit for today: if news comes straight from the horse’s mouth, it comes from the person directly concerned—the most reliable source.

That segment was written by Samantha Enslen, who runs Dragonfly Editorial. You can find her at dragonflyeditorial.com or on Twitter as @DragonflyEdit.


Ammer, Christine. From the horse’s mouth. American Heritage Dictionary of Idioms, 2nd ed. Houghton Mifflin Harcourt, 2013. 

Ayto, John. Horse, (straight) from the horse’s mouth. Oxford Dictionary of English Idioms, 3rd ed. Oxford University Press, 2010.

Oxford English Dictionary, online edition. Oxford University Press. http://bit.ly/28Ng58J (subscription required, accessed June 20, 2016).

Dent, Susie. Brewer’s Dictionary of Phrase and Fable, 19th ed. Chambers Harrap, 2012.

Image courtesy of Shutterstock.

About the Author

Samantha Enslen, Writing for Grammar Girl

Samantha Enslen is an award-winning writer who has worked in publishing for more than 20 years. She runs Dragonfly Editorial, an agency that provides copywriting, editing, and design for scientific, medical, technical, and corporate materials. Sam is the vice president of ACES, The Society for Editing, and is the managing editor of Tracking Changes, ACES' quarterly journal.

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