Where Do Zoo Animals Go When They Die?To the lab, the museum, and the education department.

By Daniel Engber
Posted Friday, Jan. 27, 2006, at 6:02 PM ET

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Veterinarians at the National Zoo put down two animals this week: an arthritic, 40-year-old elephant named Toni and a 13-year-old cheetah with kidney problems named Wandu. What happens to zoo animals when they die?

First, a necropsy is performed, and then the remains are cremated. The carcasses of all animals that die at the National Zoo-including those that wander into the park from outside-are brought to an on-site pathology lab for thorough examination. Zoo staffers identify the cause of death (if it isn't already known) and preserve tissue samples that might be important for research or education. (The zoo maintains an archive of formalin-soaked specimens from every animal that's died there since the 1970s; the Bronx Zoo has tissue samples dating back to 1920.) After the necropsy, Toni's carcass-which weighs thousands of pounds-was shipped to a lab in College Park, Md., where it will be incinerated starting Friday. The process should take about 24 hours.

Toni, like other elephants, is part of a national conservation program that has its own protocol for necropsies, as well as an updated list of which body parts should be saved. Instructions for elephant necropsies, for example, suggest a "chain saw, axe, or reciprocating saw to cut through the cranium" and "carts on rollers to move heavy parts." (Click here for a document that describes the procedure.) The elephant parts now in demand for research purposes include intact brains, eyes, and "two whole large thoracic ribs."

Not all species are part of a national program, and not all zoos keep tissue samples from every single animal. Most of the time, parts are donated as needed. Scientists who study exotic species can ask a zoo ahead of time to save a certain body part or blood sample. The zoo's education department might also receive some excised parts. Docents could use a tortoiseshell or a patch of cheetah skin, for example, as a part of educational presentations. Natural-history museums often have a need for skulls and other bones; the Smithsonian (which runs the National Zoo) sometimes requests carcasses for their displays of taxidermic critters.

Laws on the final disposal of a dead animal vary from place to place, but incineration seems to be the most popular method. The first elephant at the Baltimore Zoo, Mary Ann, received an official burial in a Maryland graveyard when she died in 1941.