Zoetis is the largest animal health company in the world, developing, manufacturing, and selling medicines, vaccines, and diagnostics for companion animals (dogs, cats, horses) and livestock (cattle, swine, poultry, fish, sheep). Companion animals drive roughly 70% of revenue, with livestock at roughly 29%. Zoetis sells products directly to veterinarians, distributors, and livestock producers, and increasingly through retail and e-commerce channels — which now account for roughly 22% of U.S. companion animal revenue. Unlike human pharma, there are no third-party payers in animal health; purchases are out-of-pocket, making the business consumer-driven. A handful of franchises dominate: the Simparica/Simparica Trio oral parasiticide line, the Apoquel/Cytopoint dermatology franchise, and the Librela/Solensia injectable monoclonal antibodies for osteoarthritis pain. The U.S. (~54% of revenue) is heavily skewed toward companion animals, while international (~45%) is more balanced between companion animal and livestock. Zoetis grows through lifecycle innovation on existing molecules — new species, formulations, and geographies — as well as new therapeutic categories like oncology, chronic kidney disease, and cardiology. Generic competition is structurally limited in animal health, and brand loyalty among vets and pet owners tends to persist even after patent expiration. Zoetis also operates the Vetscan diagnostics platform, which it views as both a standalone growth driver and a tool to identify patient populations for new therapies.