Are horses really made into glue?

Dear Straight Dope: Cecil, you’re pretty much the man. I think I got one for you. In the old westerns and Bugs Bunny cartoons that pretty much formed my thought processes as a child, they would always threaten to send the old horse to the glue factory. The question is (a) did this really happen? and (b) if so, what’s the recipe for making horse glue? Matt Gerber

SDStaff Lynn Bodoni replies:

You get points for acknowledging Cecil as the man, but if you’d done even a little bit of reading, you’d have come across the horse/glue factory connection pretty often. It’s mostly used as a figure of speech these days, but yes, horses typically were sent to the glue factory or rendering plant back in the days when they were mostly used as work animals. These days, it’s more common (an undocumented source says 90% of all domestic horses) for unwanted horses to be sent to a slaughterhouse if still alive, or a rendering plant (AKA the knackers, the knackery) if deceased.

A joke lifted from The Joke’s On You:

There was a famous jockey that never lost a race. When asked how he achieved this, he replied, I whisper in the horse’s ear: Roses are red, violets are blue. Horses that lose are made into glue.

Animal (origin) glue is made from connective tissue, found in hoofs, bones, tendons, ligaments, and cartilage in vertebrate animals.

Rendering plants are the recycling links in the food chain. They take fat and bone trimmings from grocery stores, waste scraps from restaurants, and dead animals. They cook the meat and fat products together and grind it up. It’s used for animal feed and non-edible products like soap, various lubricants, and of course glue — the heavy kind that’s used to glue furniture together, for example.

But as I say, the rendering plant isn’t the only possible destination for a horse that’s outlived its usefulness. Horsemeat is considered a delicacy in some countries. Some slaughterhouses will happily accept and process horsemeat if it’s commercially feasible. I’ve read that they buy horses in the United States for about 50 cents a pound and sell the horsemeat overseas for about $15 a pound. The Bureau of Land Management periodically comes under fire for its wild horse/burro adoption program as reports of “adopted” animals going to the slaughterhouse surface. See here for more information.

SDStaff Lynn Bodoni, Straight Dope Science Advisory Board

Send questions to Cecil via cecil@straightdope.com.

STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL’S ONLINE AUXILIARY. THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU’D BETTER KEEP YOUR FINGERS CROSSED.

Are horses really made into glue?

A STAFF REPORT FROM THE STRAIGHT DOPE SCIENCE ADVISORY BOARD