To dose or not to dose? Or, how much to dose?

Livestock Farmers and Antibiotics

by Constance Breese

Livestock Farmers and Antibiotics

Kira Shipway

On a farm, proximity means that disease travels fast. If a pig contains a bacteria such as E. Coli, it can be passed to humans through the meat if it’s not cooked to at least 160°F.  

According to the Centers for Disease Control and Prevention about one in six Americans will get sick each year from eating food containing a pathogenic (disease causing) bacteria or virus. We usually call it food poisoning because the effects are like ingesting a poison with dramatic sudden illness and an initial unknown cause.

Organisms such as E. coli, Salmonella and Listeria are everywhere, but in very small numbers. If they come into contact with a person via food handling or eating the cells can multiply, and sickness ensues. Each step of the way from farm to table is an at risk point for contamination. Food producers work hard to prevent contamination. Each step of the way creates an opportunity for contaminants to get into the products when foods are picked, washed, bagged, trucked, stored, unpacked, displayed, refrigerated etc. For meat production specifically, transportation, holding and processing livestock at a regional slaughterhouse increases chances for bacteria to get a foothold. Reducing these steps by eating locally grown food is generally safer.

On a livestock farm, bacteria follow a similar pattern. E. coli and the like are all over the farm, generally not causing a problem. If one pig gets sick (perhaps it is weaker or smaller), the bacteria begins multiplying and could spread and challenge all the other pigs on the farm. In an effort to stop the spread of disease, is it smart to give all the pigs an antibiotic that will prevent widespread, serious illness or death? Or is it wiser to treat only the obviously sick animals with medication, risking future losses? Veterinarians like me, doctoring food animals, make decisions like this often.

In April 2012 a new task force created by the Food and Drug Administration called the Foods and Veterinary Medicine Program (FVM) started strategizing for science- based food safety and preventive control standards. Appropriate, judicious use of medically necessary antibiotics by veterinarians is the goal. One major goal is to reduce or eliminate the use of low doses of antibiotics for whole herds. These feed additives are marketed to production, large scale farms as growth enhancers. What’s going on here?

Of course it is a relatively easy sell for a drug manufacturer to tell a farmer that adding low doses of antibiotics to his pig or poultry feed will make his animals grow faster and live healthier. However, the science on the “grow faster” part of the claim is dated and questionable. The unfortunate consequence to adding antibiotics to the animals’ daily ration is the evolution of populations of farm animals with weaker constitutions, not stronger immune systems. Improvements in the nutritive value of animal feeds and better quality housing for farm animals should drive out this dangerous practice. The USDA is studying the antibacterial effects of vitamin D and other non-antibiotic substances in order to reduce the use of antibiotics in farm animals. As a vet, I need new strategies to fight infections if antibiotic use is going to be reduced. Disease prevention has to move to the forefront rather than treatment of disease outbreaks.

Meanwhile, stronger and more potent bacteria are evolving too. When sub therapeutic (lower doses than if an animal were actually sick) antibiotics are fed to animals, the sensitive bacteria die, but a small number of the strongest survive. When these bacteria persist on the farm and grow, antibiotics become less effective (the bacteria become antibiotic resistant). People can be exposed to antibiotic-resistant bacteria by eating contaminated food, and doctors may not have an antibiotic to offer that will work. Food safety requires farm inspections and product inspection and is fairly routine but not without loopholes. The new FVM program will educate and employ officials to step up the safety compliance at the farm level and improve product labeling.

Lots of detective work at different levels kicks into gear when there is a suspected outbreak of a food-borne illness. I started thinking seriously about this when I was
around seven years old. My father studied animal viruses at the Plum Island Animal Disease Center, a tightly quarantined research laboratory off the tip of Long Island. He took a ferry to work every day and worked in buildings without windows. We couldn’t ever visit Dad at work (not once in 30 years). My dad couldn’t go to dairy farms or watch me ride horses. All the rules and regulations were in place to protect our food source. Many layers of investigation have been added including DNA mapping and matching of E. coli with a national reporting system and database.

On rare occasions, a sick farm animal or the blood test results from routine regulatory testing on an apparently healthy animal on the Vineyard triggers a response from state and or federal authorities. There is a fast, coordinated effort among the various arms of government and local officials. In a full circle event this year, some samples I collected alongside federal veterinary public health officials were sent to Plum Island Laboratories for analysis. To my knowledge no Martha’s Vineyard food animal farms have been documented to harbor any dangerous bacteria that would endanger our local food supply. I will do my part to keep it that way.