The Curious Case of Contraceptives in U.S. Zoos

Some of the country’s captive animals are on birth control — and sometimes it works a little too well.

National Journal
Marina Koren
June 26, 2014, 1:10 a.m.

Each year, hun­dreds of an­im­als in European zoos are killed.

None of them are sick. Some are eu­th­an­ized in or­der to main­tain the num­ber of an­im­als a zoo is able to care for, oth­ers be­cause zoo­keep­ers do not find them suit­able for breed­ing. A gir­affe named Mari­us was killed this year for the lat­ter reas­on. The Copen­ha­gen Zoo, which eu­th­an­izes ap­prox­im­ately 25 healthy an­im­als every year, shot the gir­affe and then dis­membered it in front of vis­it­ors.

You won’t hear any­thing as gory or heart­less hap­pen­ing in the United States, though. That’s be­cause Amer­ic­an zoos prefer con­tra­cep­tion over eu­thanas­ia to curb pop­u­la­tions, pre­vent breed­ing, or pre­serve ge­net­ic qual­it­ies of a giv­en spe­cies. Creatures as big as lions and hip­pos and as small as meerkats and mice take birth con­trol — it’s crushed up in their feed, in­jec­ted in­to their veins, and im­planted un­der their skins.

The As­so­ci­ation of Zoos and Aquar­i­ums, the gov­ern­ing body of U.S. zoos, al­lows eu­thanas­ia, but it’s usu­ally re­served for ill or aging an­im­als. Plus, our an­im­al-lov­ing so­ci­ety can’t quite stom­ach the idea of put­ting down a zoo an­im­al for os­tens­ibly no reas­on, es­pe­cially chim­pan­zees and oth­er prim­ates, giv­en their sim­il­ar­it­ies to hu­mans.

“On an emo­tion­al level, I can’t ima­gine do­ing it and I can’t ima­gine our cul­ture ac­cept­ing it,” Cheryl Asa, the dir­ect­or of the Wild­life Con­tra­cep­tion Cen­ter, told Leslie Kauf­man of The New York Times in 2012, sug­gest­ing that con­tra­cep­tion is the bet­ter op­tion. “By pre­vent­ing the birth of an­im­als bey­ond car­ry­ing ca­pa­city, more an­im­als can be well cared for,” she said.

The Wild­life Con­tra­cep­tion Cen­ter, an arm of the As­so­ci­ation of Zoos and Aquar­i­ums, is the cap­it­al of exot­ic an­im­al con­tra­cep­tion in the U.S. Es­tab­lished in 1999, the St. Louis cen­ter provides in­form­a­tion about and mon­it­ors the use of con­tra­cep­tion for cap­tive wild­life in 200 Amer­ic­an zoos.

In the U.S., the ad­min­is­tra­tion of hor­mon­al birth con­trol in zoos began in the 1970s. Zoos were hav­ing trouble pre­vent­ing un­wanted preg­nan­cies and were selling or giv­ing away an­im­als they no longer had room for. The prac­tice co­in­cided with a grow­ing ac­cept­ance of birth con­trol use by hu­mans.

An­im­al birth con­trol comes in many forms: hor­mon­al treat­ments like pro­gestins, es­tro­gen, and pro­ges­ter­one; GnRH ag­on­ists, which sup­press the re­pro­duct­ive en­do­crine sys­tem; vac­cines, which cre­ate an­ti­bod­ies that block fer­til­iz­a­tion; and oth­ers.

Apes and mon­keys are the easi­est an­im­als to treat with con­tra­cept­ives, thanks to their bio­lo­gic­al re­semb­lance to hu­mans. They even ex­per­i­ence some of the same side ef­fects as wo­men on hor­mon­al birth con­trol, like weight gain. Car­ni­vores are the trick­i­est — the chem­ic­als that work on prim­ates ac­tu­ally stim­u­late car­ni­vores’ uter­uses, which can res­ult in tu­mor growth. Birth con­trol can also be ad­min­istered in male an­im­als, but zoos tend to avoid that prac­tice, es­pe­cially in lions. Some con­tra­cept­ive drugs cause lions to lose their bushy manes — and, by some ex­ten­sion, what makes vis­it­ors at­trac­ted to them.

But con­tra­cep­tion use in zoos has a dark side. Many drugs haven’t been com­mer­cially ap­proved by the Food and Drug Ad­min­is­tra­tion, yet they re­main in reg­u­lar use across the coun­try. The treat­ments are con­sidered “ex­per­i­ment­al,” and their use de­pends on ap­prov­al from the In­sti­tu­tion­al An­im­al Care and Use Com­mit­tee, which re­views pro­to­cols for an­im­al re­search. They must also be in com­pli­ance with the An­im­al Wel­fare Act, U.S. De­part­ment of Ag­ri­cul­ture-en­forced le­gis­la­tion that spells out an­im­al wel­fare reg­u­la­tions.

One of these ex­per­i­ment­al drugs — and one of the first ever to be used in zoos, in 1975 — Melengestrol acet­ate (MGA), led to neg­at­ive side ef­fects in cap­tive lions, in­clud­ing le­sions, ster­il­ity, and even death. In the early 2000s, it was re­placed by an­oth­er ex­per­i­ment­al con­tra­cept­ive called Suprelor­in, a GnRH ag­on­ist about the size of a grain of rice that is im­planted be­neath the an­im­al’s skin.

Suprelor­in re­mains in use today. It has also worked al­most too well, which has the zoo com­munity wor­ried. The slow-re­leas­ing hor­mones, meant to last six months to a year, were not wear­ing off sev­er­al years after the im­plants were re­moved from lions. “I think it was sort of re­com­men­ded across the board without really know­ing what the long-term con­sequences were go­ing to be,” Re­becca Snyder, the cur­at­or of mam­mals at Zoo At­lanta, told Dav­id Hunn of the St. Louis Post-Dis­patch in Feb­ru­ary. There, zoo­keep­ers are still wait­ing for a li­on­ess to get preg­nant after she stopped re­ceiv­ing birth con­trol. “I think we all learned a les­son from that.”

Ac­cord­ing to the Wild­life Con­tra­cep­tion Cen­ter, out of more than 200 spe­cies treated with Suprelor­in, only 50 have got­ten preg­nant or pro­duced sperm again after ceas­ing treat­ment — 88 an­im­als in total.

The use of con­tra­cept­ive drugs is a re­l­at­ively new ven­ture in the zoo busi­ness (and the hu­man busi­ness, too). Over the last few dec­ades, ex­perts have de­pended on tri­al and er­ror to find the right dosage based on an an­im­al’s age and be­ha­vi­or­al and so­cial factors. And they still can nev­er be sure how long it will take for an­im­als to re­gain their fer­til­ity once they’re off the med­ic­a­tion.

Re­search­ers say it’s far too early to draw con­clu­sions. Many zoos have not yet tried to breed an­im­als who were once ad­min­istered birth con­trol. But in the case of Suprelor­in and oth­er ex­per­i­ment­al drugs, the re­turn of fer­til­ity seems not to be guar­an­teed.

“I think we all should be wor­ried,” Bud­han Pukazhenthi, a re­pro­duct­ive physiolo­gist at the Smith­so­ni­an Na­tion­al Zoo’s Con­ser­va­tion Bio­logy In­sti­tute, told Hunn. “I think we also should use a lot more cau­tion when we make the de­cision to place an an­im­al on con­tra­cep­tion.”

What We're Following See More »
CONTRARY TO REPORTS
Ryan Not Endorsing Trump Just Yet
25 minutes ago
THE LATEST
SHORT ON LACTATION STATIONS, CHANGING TABLES
U.S. Capitol Doesn’t Meet Standards for New Moms
1 hours ago
WHY WE CARE

"The U.S. Capitol does not meet the federal government’s own standards for accommodations for new mothers," according to an investigation by NBC Channel 4. "Though the U.S. General Services Administration, a government agency which oversees the management of federal government buildings, requires a minimum number of lactation stations and changing tables, Congress is exempt from the rules and fails to meet those standards." The Capitol grounds have 12 lactations stations, far short of the 42 that would be required given the number of female workers there.

Source:
OTHER SECRETARIES AT FAULT, TOO
State Dept. Review Faults Clinton Email Management
2 hours ago
THE LATEST

"A State Department audit has faulted Hillary Clinton and previous secretaries of state for poorly managing email and other computer information and slowly responding to new cybersecurity risks. ... It cites 'longstanding, systemic weaknesses' related to communications. These started before Clinton's appointment as secretary of state, but her failures were singled out as more serious."

Source:
CRUZ STILL TOOK DELEGATES AT THE CONVENTION
Trump Rolls in Washington Primary
2 hours ago
THE LATEST

Donald Trump "was on course to win more than three-quarters of the vote in Washington's primary" last night. Ted Cruz's defunct candidacy still pulled about 10 percent. "Cruz dropped out of the race on May 3, but won 40 of the state's 41 delegates up for grabs at last weekend's state GOP convention."

Source:
MULTIPLE OFFICERS INJURED
Trump Rally Turns Violent in New Mexico
3 hours ago
WHY WE CARE

"What started as a calm protest outside Donald Trump’s rally Tuesday erupted into fiery violence as protesters jumped on police cars, smashed windows and fought with Trump supporters and police. Police faced such an angry crowd that they called in reinforcements from around the state, seeking to double their numbers to counter the protesters, whose numbers swelled beyond 600." Protesters threw rocks and bottles at police, who broke up several fights. 

Source:
×