The world's top animal health firms are: Zoetis (formerly Pfizer), Merck, Merial, Eli Lilly, Bayer, Boehringer, and Novartis. They are enjoying a growth rate of about five percent a year. One common corporate strategy is to leverage human drugs for the animal market. And, from a corporate perspective, why not? There are only seven billion humans, but 100 billion or so farm animals. That's a lot more flesh and bones to keep medicated. Concerned consumers have many reasons for not wanting to support this industry. Not only are millions of animals subjected to brutal tests in order to create these drugs, but the impact of these drugs on global ecosystems is substantial. These drugs enter the environment through excrement, urine, and direct disposal. The State of Washington notes how it can all come back to us: "Landfill leachate can contain trace amounts of pharmaceuticals as well. Often this leachate is sent to the same wastewater treatment systems that receive residential wastewater."
The takeaway here is this: Our choice to raise billions of animals for food requires more than land, air, and water–all of which is bad enough. So much more is hidden from us. When we eat animals we often fail to understand the how broadly the ripple effects extend. Growing plants is hardly a chemically harmless endeavor, but it's nothing like animal ag, where every hour is pharmaceutical cocktail hour.