When You Hear Hoofbeats Look for Horses Not Zebras

Hilton Read? Theodore E. Woodward? Ele and Walt Dulaney? Harley S. Smyth? Anonymous?

Dear Quote Investigator: In medicine the symptoms of a patient are often compatible with a variety of ailments. A skilled diagnostician will use probabilistic reasoning when deciding which ailment is the most likely. Bayesian inference first highlights common maladies instead of rare ones. Here are three versions of a germane saying:

  • When you hear hoofbeats look for horses not zebras.
  • If you hear hoof beats in the distance don’t expect a zebra.
  • When you hear hooves think of horses before zebras.

Admittedly, these adages work best outside of a zoo and on a non-African continent. Would you please examine the provenance of this saying?

Quote Investigator: The earliest published evidence located by QI appeared in the “Arkansas Gazette” of Little Rock, Arkansas in October 1962. Emphasis added to excerpts by QI: 1

The father of a young man who was there reports that at the University of Arkansas School of Medicine this week a doctor surrounded himself with about a dozen students and sought to go to the heart of proper diagnostic procedure.

In the end he summed up good diagnosis this way: “When you hear hoofbeats in the night, look for horses — not zebras.”

The passage above occurred in a column called “Our Town” by Charles Allbright, but the participants were unidentified.

An earlier origin for the saying has been suggested. However, the claim is weakened by a multi-decade delay. For example, a variant statement has been ascribed to Dr. Theodore E. Woodward circa 1940s. Evidentiary support appeared in the 1980s. See the citations further below.

This article presents a snapshot of current knowledge, and future researchers may discover material that alters the ascription.

Here are additional selected citations.

In May 1964 “Reader’s Digest” magazine published a profile Dr. Hilton Read who was described as a bag toting family physician of 65. Read received credit for the saying: 2

Doc Read fixed me with probing blue eyes, then grinned and said tolerantly, “Jack, if you hear hoofbeats around here, you can usually bet they’re made by horses, not zebras. Fortunately, when somebody gets sick, the trouble is usually something common, not one of those exotic diseases they dramatize in medical schools.

In July 1964 a syndicated column called “Date-line” by Ele and Walt Dulaney placed an instance of the saying between quotation marks signaling that it was already in circulation: 3

We think you’re kidding, but just in case this question’s for real—we’d say the boy was borrowing from his sister’s stationery because he was too cheap to invest in his own. “Don’t look for zebras when you hear hoofbeats in the hall!”

In November 1964 the saying appeared again in the Dulaney’s column, but the word-order was altered: 4

Better heed the folk truth, “When you hear hoofbeats in the hall, don’t look for zebras.”

In April 1969 an Albany, New York newspaper printed an instance within a column about birdwatching. No attribution was listed, and the words were enclosed between quotation marks: 5

“When you hear hoof beats, look for horses, not zebras.”

In December 1969 the expression appeared in the syndicated column of Ele and Walt Dulaney yet again. This time it was labeled Yiddish: 6

There’s an old Yiddish saying I’m fond of. The gist of it is, “If you hear hoofbeats in the hall, why expect a zebra?”

In 1971 the “American Journal of Public Health” printed an interesting variant featuring a unicorn: 7

There is an old adage about the probability of pathological esoterica that is pertinent: “When you hear hoofbeats in the garden, do not expect to see a unicorn when you look out the window. It will probably be a horse.”

In 1973 the “Detroit Free Press” printed an anecdote about a pediatrician featuring a variant adage with a giraffe: 8

I asked the doctor what disease he was thinking of, and he said strep throat. Since there were a lot of other things it could be, I asked him why he thought of that first, and he said, ‘Because when you hear hoofbeats under your window you don’t look for a giraffe.'”

In 1986 the expression occurred in “The Fitzhenry & Whiteside Book of Quotations” with an ascription to a physician: 9

When you hear hoofbeats, think of horses before zebras.
Medical maxim quoted by Harley S. Smyth

A student at the University of Maryland at Baltimore, School of Medicine selected an interesting variant for his 1986 yearbook quotation. Greene Street is a roadway near the school: 10

“If you hear hoofbeats on Greene Street — don’t look for zebras”

In 1993 a Florida newspaper quoted a vitamin pill booster who twisted the saying: 11

Then he smoothly says in his rich radio-announcer voice:
“Unlike the vast majority of people who trod past your door, when I hear hooves sometimes I think of zebras,” he says. “Most people never think of anything but horses.”

In 1999 a letter writer in “The Baltimore Sun” of Maryland mentioned the “Greene Street” version of the saying: 12

Where I did my residency training at University of Maryland Hospital, there was an old saying that “when one hears hoof beats on Greene Street to think horses first, not zebras.”

In 2006 the book “The Medical Science of House, M.D.” referred to the efforts of Dr. John G. Sotos who attempted to explore the history of the expression: 13

Dr. Sotos says he searched for twenty years, and finally concluded that the best claim belonged to the late Theodore E. Woodward, M.D., who taught at the University of Maryland School of Medicine in Baltimore for nearly fifty years. . .

Dr. Sotos says that beginning in the 1940s Dr. Woodward admonished his medical students, “Don’t look for zebras on Greene Street,” referring to the street outside the University of Maryland medical school. Over time, the advice became more general: “When you hear hoofbeats behind you, don’t expect to see a zebra.”

In conclusion, this expression was employed by a doctor at the University of Arkansas School of Medicine by 1962, but his or her name is currently unknown. The saying was being popularized by Dr. Hilton Read by 1964 as recorded in the “Reader’s Digest”. The columnists Ele and Walt Dulaney also helped popularize the expression by 1964.

There is indirect evidence that Theodore E. Woodward used the adage at the University of Maryland at Baltimore, School of Medicine. A fellow doctor credited him with using it by the 1940s, but QI has not yet found published contemporary evidence supporting this assertion.

(Great thanks to Kevin Holbeche whose inquiry led QI to formulate this question and perform this exploration. Special thanks to Dana Dalrymple of the Spokane Public Library in Washington for acquiring scans of the 1964 Reader’s Digest citation. Many thanks to Barry Popik and Charles Doyle for their pioneering research on this topic. Also thanks to discussants Joel S. Berson, Victor Steinbok, Jonathan Lighter, Dan Goncharoff, Ronald Butters, Fred Shapiro, and Laurence Horn.)


  1. 1962 October 5, Arkansas Gazette, Section: Sports and Markets, Our Town by Charles Allbright, At First, Anyway, Quote Page 1B, Column 1, Little Rock, Arkansas. (GenealogyBank)
  2. 1964 May, The Reader’s Digest, Volume 84, My Most Unforgettable Character by John Helwig Jr. M.D. (Assistant Professor of Medicine, University of Pennsylvania), Start Page 129, Quote Page 129 and 130, The Reader’s Digest Association, Pleasantville, New York. (Verified with scans; thanks to the Spokane Public Library)
  3. 1964 July 3, The Honolulu Advertiser, Date-line: Ignore a Blase Brother and He’ll Soon Recover by Ele and Walt Dulaney, Quote Page D18, Column 4, Honolulu, Hawaii. (Newspapers_com)
  4. 1964 November 25, The Seattle Times, Date-line: First-Born Feels He Missed Privileges by Ele and Walt Dulaney, Quote Page 15, Column 3, Seattle, Washington. (GenealogyBank)
  5. 1969 April 5, The Knickerbocker News, On the Wing: A Rare Sighting by Beverly Waite, Quote Page B7, Column 2, Albany, New York. (Old Fulton)
  6. 1969 December 25, The Honolulu Advertiser, Date-line by Ele and Walt Dulaney, Quote Page C2, Column 4, Honolulu, Hawaii. (Newspapers_com)
  7. 1971 November, American Journal of Public Health: JPH, Volume 61, Number 11, Medicaid Practitioner Abuses and Excuses vs. Counterstrategy of the New York City Health Department by Lowell Eliezer Bellin and Florence Kavaler, Start Page 2201, Quote Page 2205, American Public Health Association, Inc., Hanover, Pennsylvania. (Verified on paper)
  8. 1973 August 12, Detroit Free Press, Section: Detroit Magazine, (Editorial Introduction), Quote Page 2, Column 4, Detroit, Michigan. (Newspapers_com)
  9. 1986, The Fitzhenry & Whiteside Book of Quotations, Revised and Enlarged, Edited by Robert I. Fitzhenry, Section: Medicine and Sickness, Quote Page 231, Fitzhenry & Whiteside Limited, Toronto. (Verified on paper)
  10. 1986, Terra Mariae Medicus, Yearbook of University of Maryland at Baltimore, School of Medicine, Entry for student: Charles Edward Neagle III (Orthopedics), Quotation selected by Neagle, Quote Page 127, Baltimore, Maryland. (Internet Archive at archive.org)
  11. 1993 September 19, The Palm Beach Post, Past lies don’t slow ‘magic pills’ pitch by Jane Victoria Smith (Palm Beach Post Staff Writer), Continuation title: Backers swear by vitamins, Start Page 1B, Quote Page 3B, West Palm Beach, Florida. (Newspapers_com)
  12. 1999 July 25, The Baltimore Sun, Section: Letters, Letter from: Robert B. Testani of Catonsville, Letter title: Perhaps he did spy an eagle, Quote Page 6B, Column 5, Baltimore, Maryland. (Newspapers_com)
  13. 2006, The Medical Science of House, M.D. by Andrew Holtz, Quote Page 27, Berkley Boulevard, Berkley Publishing Group, Part of Penguin Group, New York. (Google Books Preview)