Heidi Vittetoe knows a thing or two about raising healthy animals. In 31 years, she’s sent more than 6 million pigs to slaughter from her Washington County, Iowa, farm.

To ward off possible illnesses, Vittetoe routinely injects weaning piglets with virginiamycin, a prescription-grade antibiotic. For nearly the rest of their lives, she adds 10 grams of other antibiotics to every ton of the herd’s food and water supply to prevent diseases and promote growth – something that should make her “golden in the eyes of the consumer,” she said in an interview.

“The animals we raise are the animals we eat,” Vittetoe said. “We have nothing to gain by having unsafe food but everything to gain by having food that consumers will accept, and antibiotics are a tool in achieving that.”

But preventive health measures don’t guarantee safe food, according to environmental health scientist Ellen Silbergeld, who told News21 that thousands of ranchers like Vittetoe have “squandered the use of antibiotics” by feeding and injecting healthy cows, pigs, chickens and turkeys with the same drugs used to cure human infections.

The result is bacteria that can no longer be killed by antibiotics and are still present in animals when they go to slaughter, said Silbergeld, a professor at the Johns Hopkins Bloomberg School of Public Health. The bacteria end up in consumer meat products sold at grocery stores across the country.

The journal Clinical Infectious Diseases reported this year that nearly half of all beef, pork, chicken and turkey purchased from 26 retail stores in Chicago, Washington, D.C., Fort Lauderdale, Fla., Los Angeles and Flagstaff, Ariz., contained drug-resistant bacteria. While thorough cooking may kill even resistant pathogens, Silbergeld said the risk of infection from cross-contamination is too high when handling raw meat and poultry.

“Antibiotic resistance is an immediate health risk,” she said. “This is the thing that will kill you.”

While humans need a prescription, ranchers can buy antibiotics for their animals over the counter at farm supply stores across the country.

According to the U.S. Food and Drug Administration, about 80 percent – roughly 29 million pounds – of the antibiotics manufactured and sold domestically are used on farm animals. This practice has fueled controversy over their non-therapeutic use in livestock production.

The FDA acknowledged in 1977 that feeding food-producing animals antibiotics at levels too low to treat diseases enables hardy bacteria to survive in a form more resistant to medical treatment. After years of debate, the issue surfaced in Congress nearly a decade ago.

The Preservation of Antibiotics for Medical Treatment Act, sponsored by Rep. Louise Slaughter, D-N.Y., would phase out the non-therapeutic use of antibiotics given to both humans and animals.

“What we are witnessing is a looming public health crisis that is moving from farms to grocery stores to dinner tables around the country,” Slaughter, the only microbiologist in Congress, said in a recent press release. “While we’re giving antibiotics to pigs and chickens, we’re allowing people to die.”

With more than 100 co-sponsors, the legislation has been introduced in every Congress since 2002, drawing intense debate. Between January 2001 and December 2010, physicians, environmentalists and animal rights advocacy groups endorsing the legislation donated $78.2 million to members of Congress, 18 times more than livestock interest groups.

Leaders in the agriculture industry, including national and state livestock organizations and private ranchers, donated $4.4 million during the same time period, according to MAPLight.org, a nonprofit and nonpartisan research organization that tracks political contributions.

The single biggest donor opposing the legislation – the National Pork Producers Council, which represents America’s 67,000 pig farmers – challenges Slaughter’s claims.

“Our industry doesn’t know whether we’re part of the problem because there is no science linking antibiotics in food animals to antibiotic resistance,” NPPC spokesman Dave Warner said. “All antibiotic use means safer meat, and that’s our bottom line.”

But a coalition of consumer advocates and public health organizations contends the danger of antibiotic misuse is real and growing.

In May 2011, the Natural Resources Defense Council, Center for Science in the Public Interest, Food Animal Concerns Trust, Public Citizen and the Union of Concerned Scientists sued the FDA. They claim the agency’s stance on antibiotic use in farming is contributing to thousands of fatal infections in humans, costing the U.S. health care system $34 billion each year. The groups also contend that resistant pathogens develop and infect humans who can no longer be treated because the bacteria making them sick are resistant to drugs.

The Center for Science in the Public Interest, a nonprofit food safety watchdog group, filed a petition the same day demanding the U.S. Department of Agriculture recall meat and poultry tainted with drug-resistant pathogens. They urged that four salmonella strains be declared adulterants, which would make it illegal to sell products that contain any trace of the bacteria.

Meanwhile, Vittetoe said the antibiotics she uses in Iowa protect the health of her pigs during vulnerable periods, especially when they’re weaned from their mothers and begin eating solid food.

Gail R. Hansen, a veterinarian and senior officer at the Pew Charitable Trusts, equated this to treating children with antibiotics during times of stress. In June 2010, she testified before Congress on the risks of routine use of antibiotics in food-animal production.

“We don’t give our kids antibiotics to keep them from getting earaches, for example.” Hansen said in an interview with News21. “That would be considered malpractice, and you can’t go to the grocery store and pick up antibiotics to put in your kid’s Cheerios.”

Hansen’s argument has gained traction among opponents of conventional farming who say antibiotics are used to mask filthy, unsanitary living conditions, but Vittetoe is quick to disagree.

“Children are not being raised for meat and are not living in a population of 200,000 animals,” Vittetoe said. “If there’s a herd of hundreds, does it make sense that one animal would have to become demonstratively sick before we treat them?”

A pig raised for food typically has a six-month lifespan, leaving little time to get sick, partly because antibiotics promote faster growth with less feed. Scientists suspect the drugs enhance the absorption of nutrients, helping pigs gain about a pound and a half a day. From birth to slaughter, the animals grow from about 3 pounds to a market weight of 270 pounds.

Both a 2008 USDA study and a 2007 study in Public Health Reports, a journal that focuses on emerging public health issues, found that the non-therapeutic use of antibiotics in broiler chickens boosted feed efficiency enough to make the animals grow faster – but not enough to offset the expense of the drugs. Chickens raised with antibiotics cost on average about one penny more than those that are not.

Vittetoe said she spends less than an extra dollar per pig giving them antibiotics but believes the costs are outweighed by the animal’s added health and well-being.

For all the back and forth on the topic, members from both the agriculture industry and the scientific community agree that antibiotics have a place in producing safe food. The dispute is when to use them.

Hansen said antibiotics should be used to treat existing diseases in livestock. “But we have enabled a food-production system that relies too heavily on antibiotics to do what good animal husbandry could accomplish without putting human health at risk,” she said.

Vittetoe contends the practice is sound. “As a mother, I know how important safe food is, and as a pork producer I know how hard we work to provide exactly that,” she said. “Antibiotics are perceived negatively, but they offer that benefit.”