Medical Zebra
Unique and Rare

“Zebra” is a term that is used to describe a surprising diagnosis. It derives from the saying “When you hear hoof beats behind you, don’t expect to see a Zebra”. Dr. Theodore Woodward, a former professor at the University of Maryland School of Medicine in Baltimore, coined this term in the late 1940s. He explained that since horses are the most commonly encountered hoofed animal for most people and zebras are hoofed animals that are less likely encountered; one would naturally guess that the hoof beats belong to a horse and not a Zebra. By 1960, this metaphor was widely known amongst medical circles. (From Wikipedia, the free encyclopedia, 2013)


This phrase continues to be drilled into the minds of Physicians in training:


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


So, in the medical community the term “Zebra” is universally understood as a reference to a rare condition/disease. Physicians are taught to assume the most likely explanation of the condition and therefore miss more unlikely explanations of the disease. In addition, Physicians are known to be uncomfortable with diagnosing patients with “exotic” diseases that are unlikely.


Ironically, this term ZEBRA has been adopted by communities of patients with rare disorders such as Cushing’s Syndrome, Adult Human Growth Hormone Deficiency, Panhypopit, and other rare diseases. Why? Because those of us who DO have a rare disorder know from personal experience what it feels like to be dismissed by a physician or in many cases, multiple physicians. Metaphorically, many physicians have completely lost the ability to even imagine that zebras may exist!


“It is frustrating indeed, to spend years being shuffled from specialist to specialist, seeking diagnosis and treatment for a condition that no one can seem to identify.” (, 2013)


We have started a Zebra movement. We call ourselves the “Zebra Crew”! We recognize that this is a term that represents those of us who have these RARE disorders that can go undiagnosed for many years, on average between 3-7 years! However, Zebra is not a weak term! It is a term that acknowledges how strong we are, brave, courageous, beautiful. We bond through the recognition that we have all endured being misidentified as horses!