If you were following the U.S. presidential campaign in late summer, it was easy to imagine you'd switched channels and were watching "Animal Planet." Republican vice-presidential candidate Sarah Palin compared "hockey moms" to pit bulls (with the addition of lipstick), and Democratic presidential candidate Barack Obama spoke of his rival John McCain's policies as "lipstick on a pig" (which he said meant "mere window dressing").

(Come to think, that's lot more lipstick than we're used to seeing in politics, too. I look forward to future coinages such as "a llama in mascara" and "nail polish on a centipede.")

But here's my main point: terriers and porkers aren't the only animals in our political lexicon. In fact, it's a real zoo out there.

Let's start with man's best friend. Dogs have been making political headlines in the United States since at least 1988, when dog-whistle politics first appeared in the Washington Post. The term, which means "coded or concealed ideas that are transparent to their intended audience"—a dog whistle is pitched too high to be audible to humans, but can be heard by dogs—apparently originated in Australia or New Zealand. When Mike Huckabee, a former Baptist minister, was campaigning in the Republican primaries earlier this year, many observers noticed that his stump speeches contained language—including explicit references to Bible texts—that his fellow evangelicals would recognize as religious. (In Huckabee's case, the dog whistle sometimes malfunctioned. Last spring, National Public Radio interviewed several self-described Christians who had no idea what Huckabee had meant when he talked about "a small, smooth stone" or "the widow's mite"—references to the David and Goliath story and to one of Jesus' parables about the dignity of poverty, respectively.)

Ever wonder what pork-barrel spending has to do with pigs? Since the late nineteenth century, "pork" has been a metaphor for government spending that benefits constituents of a particular politician in exchange for support at the polls. It likely evolved as a colorful synonym for "fat." According to some sources, pork barrel derives from a tradition on Southern plantations in which barrels of salt pork were given to slaves as special treats. Use of the term has spread to other English-speaking countries such as Australia, New Zealand, and the United Kingdom; in Scandinavian countries, however, words meaning "election pork"—such as Swedish valfläsk—refer to promises made before an election (and rarely kept). Elsewhere, the "pre-election promise" concept is expressed in other meaty words: Czech předvolební guláš (pre-election goulash), Finnish vaalikarja (election cattle), and Polish kieɫbasa wyborcza, for example.

Close relations of pork-barrel spending are the ubiquitous earmarks. In the world of politics, earmarks are provisions that guarantee how funds can be used. But when the term first appeared, in the sixteenth century, it meant a literal mark, or cut, on the ear of an animal—cow, pig, or sheep—that proved the animal's ownership and gender.

We also hear about bellwether states or counties whose political choices point toward a more general trend. (Notice that there is no weather in bellwether.) Our agricultural ancestors, though, had a different association for the word. Wether comes to us from Old English, in which it meant a male sheep, usually castrated; a bellwether was a sheep that wore a bell around its neck and led the flock. That "leadership" meaning is what we retain today.

Some members of the flock—or herd—stubbornly go their own way. These rebels are known as mavericks, after the term used for an unbranded range animal in the American West. The word itself is an eponym, from the surname of a nineteenth-century Texas lawyer and politician named Samuel Maverick who refused to brand his cattle (and, some fellow Texans complained, blithely rounded up all unbranded cattle and claimed them as his property). Today, some politicians—most notably Republican Senator John McCain—have turned "maverick" into a successful brand of its own.

Worried that your maverick candidate may not have what it takes to represent you? Then you'll want to vet him or her. A relatively recent arrival in American English—it was still unusual enough in 1980 that language columnist William Safire explained it to his New York Times readers—vet is nothing more than a shortening of the Latinate word for animal doctor, veterinarian. The verb form became popular in England in the late nineteenth century, when it meant "to check out an animal," in particular a racehorse; it got its more general meaning of "evaluate" in the early 1900s, and became very popular beginning in the 1930s. As recently as the 1980s it was used mostly in reference to documents: to "vet a manuscript" means to check its facts. It gradually came to apply to humans as well.

You might expect to see a lot of vetting—and griping—on a zoo plane, the less-prestigious plane on which TV crews (sometimes called "animals"), journalists, and campaign staff travel during a campaign. In his Political Dictionary, William Safire—who once served as a speechwriter for President Richard Nixon—tells of first hearing the phrase in 1968 from Nixon's press secretary, Ronald Ziegler. "You'll never get off the zoo plane after this," Ziegler joked to a pool reporter who had written about a Nixon gaffe. The phrase was popularized by Hunter S. Thompson in his 1972 book, Fear and Loathing on the Campaign Trail. In Thompson's account, the zoo plane carrying the journalists who were covering candidate George McGovern was loaded with recreational drugs, lending an extra meaning to the phrase "political party."