Scientists here sit bent over microscopes at black countertops—it feels more high-school biology than government-funded science lab. They spend hours a day looking at blood, tissue, and fecal samples from creatures that have rarely if ever been studied in such detail. Their job is to diagnose health problems in live animals and to determine what killed an animal.
Dr. Tim Walsh runs the department. He’s the third person to hold the position since the National Zoo hired its first pathologist in the 1960s. Today this is one of only seven zoo-based pathology programs in the country.
“You’re dealing with creatures that might have never been looked at before,” Walsh says. “It’s a lot of investigation, a lot of discovery, and you get a lot of answers.”
Walsh earned his doctorate at the University of Missouri and in 1993 began a zoo-pathology residency in Chicago. When he graduated, there were no zoo jobs available, so he took a pathologist position at Washington State University’s veterinary college, working on domestic animals, birds, and fish. He did a stint in the Galápagos studying avian diseases, then came to the National Zoo as head pathologist in 2006.
Walsh calls himself an animal coroner—his only hands-on work with zoo animals comes after they’ve died. But like a heart surgeon, he’s always on call, sometimes rushing to work in the middle of the night to begin a necropsy, an animal autopsy. He says time is of the essence when tracking a microscopic killer: “The best information comes from a fresh specimen.”
On average, four to five animals die at the National Zoo every week. While lions, tigers, and other large mammals die infrequently, the zoo’s collection of roughly 2,000 creatures includes species with much shorter life spans, such as fish and insects. (While the zoo weathered controversy over seemingly preventable animal deaths under the leadership of former director Lucy Spelman, today’s death rate is about normal for the size and breadth of its collection.) Walsh and his team perform necropsies on every one.
From the outside, the necropsy building looks like a storage facility. An accordion-style garage door creates an opening to get large animals, such as elephants, inside. A truck can back up to it, and a built-in crane can lift and move animals onto the operating table.
Like any operating room, this one is cold and sparse. There’s nowhere to sit and nothing built for comfort; the concrete floor and stainless-steel table are meant to withstand post-op hose-downs. The doctors’ tools are kept at arm’s length: delicate forceps and tiny scalpels for small creatures, a band saw for large ones.
A necropsy is a meticulous process. Zoo pathologists approach each with the same goals: to understand what killed an animal, to identify whether the cause of death poses a threat to other animals, and to collect samples for further research. While human and domestic-animal pathologists are trained to look for misshapen blood cells, enlarged organs, or anything else out of the ordinary, zoo pathologists have to approach exotic animals with open minds, figuring out what’s normal before looking for oddities.
“We venture into uncharted territory,” Walsh says. “We make comparisons with more-studied animals when we can, but sometimes we’re literally writing the book.”
When a necropsy is complete, the zoo keeps samples and specimens for its records (“We’re Smithsonian—we don’t throw anything away,” says Walsh) and offers remains to other Smithsonian branches. The National Museum of Natural History usually takes most of them, using skulls and skins in their exhibits and blood samples for DNA research. To give out the rest, the department consults what it calls the Carcass Wishlist, a database of tissue requests from researchers at non-Smithsonian institutions. There were 884 requests at last count; most are for elephants.
Next: The future doesn't look good for Asian elephants.