An investigative article focusing on the potential human health threat of livestock antibiotic residues painted an inaccurate picture of U.S. dairy farming, cattle ranching and the food animal drug regulatory process, according to Dr. Roger Saltman, a veterinarian with Zoetis, maker of the drug highlighted in the article.

Meanwhile, one of the leading congressional advocates for increased regulation and bans on some antibiotics in animal agriculture, U.S. Rep Louise Slaughter, said the article’s information illustrates why her legislation is needed.

The Reuters’ article, “Farmaceuticals: On American dairy farms, sharp rise in the misuse of a potent but risky drug”, alleges misuse of the antibiotic ceftiofur on U.S. farms has created a threat to human health. 

In a telephone conference call with dairy/livestock media late last week, Saltman, DVM, MBA, Group Director for Cattle and Equine Technical Services, said company representatives sat down with the authors of the article to provide background information. Much of that information was left out, leaving the impression the U.S. meat and milk supply is unsafe.

Saltman, who was a dairy farmer and dairy veterinarian prior to joining Zoetis, defended USDA's food safety monitoring program, saying there are a remarkably low number of true antibiotic residue violations that potentially enter the food supply.

USDA’s two-part program includes scheduled random sampling, designed to gain statistical insights about the prevalence of drug residues in animals going into the food chain.

“These violations are extremely low,” Saltman said. “There were three violations in the first half of 2014, representing more than 275,000 assays from 3,000 samples. Not one of them involved ceftiofur.”

“The statistics cited in the Reuters’ article were taken from a second component of the residue monitoring system, the inspector generated program,” he continued. “The intent of this program is not to estimate the prevalence of residues, but rather specifically targets suspect animals and suspect populations of animals. Inspectors observe every animal as they are presented for harvest. If those inspectors have any concerns about the health of the animal, those animals are pulled from the line. Meat from the animal is evaluated and tests for antibiotic residues are run. (Carcasses) are held while waiting for the test outcome. If the meat contains any residue violations or if the animal is condemned for any reason, it does not enter the food chain,” he said.

“Antibiotic violations are typically higher among the unhealthy animals pulled from the (slaughter) line by inspectors, including the violations the Reuters’ article described related to ceftiofur,” Saltman explained. “All these animals are identified by inspectors. They really are a small percentage of the total number of animals, and it's important to underscore these animals did not enter the food supply.”

Withdrawal time

Saltman defended the government’s drug approval process, including determining drug withdrawal times. And, he said, there's science behind differing withdrawal times based on administration of ceftiofur – a differentiation not recognized in the article.

“There’s a real difference between withdrawal times when using an injectable product, which is distributed to the bloodstream, versus a compound that is administered via intramammary injection,” he explained.

“Ceftiofur injected into the bloodstream will not leave the bloodstream and go into the mammary gland,” he explained. “It's called the blood-milk stream barrier; it doesn't penetrate the mammary gland, and that's why injectable ceftiofur products do not have a milk withdrawal time. They simply don't get into milk.”

In addition, while introduction of any antibiotic results in bacteria developing some transient resistance in the GI tract or gut, these bacteria remain in the gut and are largely overwhelmed by susceptible bacteria within 10-14 days. There's no science to indicate resistance that occurs in the gut of the animal – removed at slaughter as offal – gets into the animal’s meat or milk, he said.

“There is no concern or need to extend withdrawal periods,” Saltman said. “It's a rigorous process to get a drug approved, and we're confidant in FDA’s process.”

Slaughter responds

“This report is truly shocking – livestock have been overdosed with antibiotics as a way to keep them alive long enough to reach the slaughterhouse, and mandatory regulations on the correct withdrawal period for drugs have been ignored, resulting in antibiotic-laced meat being passed on to the consumer,” said Slaughter (D-N.Y.), the author The Preservation of Antibiotics for Medical Treatment Act. “The industry has blatantly violated mandatory guidelines on antibiotic use, calling into question how much faith we can place in industry to adhere to the FDA’s voluntary guideline limiting the overuse of antibiotics, which the FDA claims will be faster and more effective than mandatory regulations.”

Education efforts

The Reuters’ article quotes retired Kentucky dairy farmer Hugh Bryon, cited for an antibiotic residue violation in 2010, who admitted cull cow prices are an economic incentive to “fudge it” – sending animals treated with ceftiofur to the slaughter market before the specified withdrawal period. The article further states cattle producers face light consequences if the slaughtered animal is found to contain antibiotic residues.

“This is a blot on our industry, but we have to recognize there may be dairy farmers who ‘fudge it’,” said Saltman. “I think it's very rare, but it is something our industry cannot accept.”

“When a violation is recognized, it starts an investigation on the farm where the animal originated,” he said. “Many of these violations were found to be the result of inadequate veterinarian involvement to be sure the labels guidelines were met, not only giving these medicines, but also following the withholding period. Other common reasons using drugs in ways they were not approved (off-label usage), and sometimes due to inaccurate record-keeping, leading to mistakes.”

”We need to strengthen our stewardship efforts, making sure of the proper and responsible use of antibiotics,” he said. “It's an effort we all need to make.”

Zoetis’s “Join the Cause” campaign includes meetings with producers, veterinarians and field sanitarians, underscoring the responsible use of antibiotics. The programs stress the need for veterinarian guidance on antibiotic use, including diagnosis of a disease, and oversight that there is no procedural drift when using antibiotics.

A website, provides tools to help people understand the proper use of medicines and avoid residues.

“For me, the take-home message is that we have to re-double our efforts to be sure that before we take an animal to harvest, before we put that animal on the truck, that we have to be doubly sure we have followed the proper withdrawal times, that there were no mistakes made using the antibiotic,” Saltman said. “Finally, we have to decide if these animals are appropriate to go into the food chain. Would these be animals we would harvest ourselves and put on our own table? If they aren't, we should not send them to slaughter, because they are the ones being detected in anti-mortem inspections, and these are animals in which residues are being detected.

We can't be tempted to fudge it,” he said. ”In the times we live in now, we have to follow every possible protocol we can legally and technically to ensure we don't send animals not fit or slaughter to market.”