Of Cats and Cows, Drugs and Drug Resistance
This guest blog was written by Jessica Magenwirth, DVM, a veterinarian and Masters in Public Health candidate with a focus on global health and policy at the Johns Hopkins Bloomberg School of Public Health.
Antibiotics given to livestock make up roughly two-thirds of all global use of antibiotics, with the rest intended for medical use in people, according to Ramanan Laxminarayan of the Center for Disease Dynamics, Economics and Policy (CDDEP). No wonder major health bodies, like the World Health Organization and the Centers for Disease Control and Prevention, point to livestock use of antibiotics as a significant contributor to the global epidemic of antibiotic resistance. Use and overuse of antibiotics, after all, is what drives resistance at the most fundamental level.
So why do we find former USDA officials like Richard Raymond trying to distract attention on antibiotic overuse away from livestock and onto pets, instead? Or like James MacDonald, current branch chief at USDA’s Economic Research Service, who at the National Food Policy Conference this past April called into question the notion that livestock overuse of antibiotics factors into the 23% increase in antibiotic sales for use in animals 2009 to 2014? Antibiotics in pets, rather than livestock, could account for that increase, MacDonald suggested.
Basically, I set out to answer this question. When it comes to stopping superbugs, should cats deserve more scrutiny than cattle?
What say the FDA’s data?
The Food and Drug Administration (FDA) collects manufacturers’ data on pharmaceutical sales. The 2014 data show that 96% of the “medically important” antimicrobials (those important to human medicine) sold for use in animals were product formulations that were intended to be added to animal feed or water. This method of administration is pretty much unique to livestock or poultry. Antibiotics aren’t normally given to people in their cereal after all, nor to pets in their water or food dishes!
For the sake of discussion, let’s assume that the entirety of the remaining 4% of medically important antibiotics were either injected, applied topically, or squirted directly into the mouths of our pets. That is still a pretty small number, relative to the much bigger use in livestock.
Recently the FDA—in part, I suspect, responding to the confusion created by their colleagues over at the USDA—posted the following on its website:
“Of the more than 130 actively marketed, medically important antimicrobial products approved for use in food-producing animals in 2014, there are only 12 actively marketed drug products approved for both food-producing animals and companion animals…. and [these products] collectively represented 143,360 kg of active ingredient domestic sales in 2014. There was a total of 9,475,989 kg of active ingredient domestic sales reported in 2014 for the medically important antimicrobial products.”
To paraphrase the FDA, it looks like just over 1.5% of medically important products sold in 2014 (143,360 kg /9,475,989 kg of active ingredient) were FDA-approved to be used either in pets or in livestock. We can’t know the actual percentage bought for and used in pets, rather than food animals. But the strong likelihood is that it is even lower than 1.5%. To avoid further misunderstanding, the FDA adds: “The use of these twelve drug products in companion animals likely has little to no effect on trends in the overall reported sales of antimicrobial drugs.”
So, Drs. Raymond and MacDonald, to answer my own question, I guess antibiotics given to cats (or dogs or pet birds) in fact don’t deserve as much attention as cattle (pigs and poultry). The data are indisputable.
Where to go from here - the way to action
Every ten minutes, a patient in Europe or the U.S. dies because antibiotics have failed to treat their nasty bacterial infection. The toll is only expected to worsen. Dr. Margaret Chan, WHO’s Director-General, has left no doubt where she stands, recently stating: “[A]ntimicrobial resistance is a global crisis. It is bad and getting worse”. Without timely action the terrifying reality of a “post-antibiotic” world will arrive faster than we can imagine, or prepare for it.
Meanwhile, a recent CDDEP report concludes that "more antibiotics are used in poultry, swine, and cattle to promote growth and prevent disease than are used by the entire human population.” Earlier this year Lord Jim O’Neill, who chaired the Global Review on Antimicrobial Resistance, recommended that globally countries should limit their use of antibiotics in food animals to no more than 50 mg per kilo of meat produced.
The best available estimates are that the U.S. consumes around 180 mg of antibiotic active ingredient per kilo of meat produced, while leading European meat producers like Denmark use only about one-fourth that amount. As one of the world’s biggest meat producers and antibiotic consumers, it’s time for us in the U.S. stop blaming cats and look closer at how we raise our chickens, pigs and cows We all bear responsibility for greatly limiting our overuse of antibiotics in livestock, and quickly—and vets can and should play a key role in leading the way.