Merck & Co. engages in the provision of health solutions through its prescription medicines, vaccines, biologic therapies, animal health, and consumer care products. It operates through the following segments: Pharmaceutical, Animal Health, Healthcare Services, and Alliances. The Pharmaceutical segment includes human health pharmaceutical and vaccine products. The Animal Health segment discovers, develops, manufactures, and markets animal health products, such as pharmaceutical and vaccine products, for the prevention, treatment and control of disease in livestock and companion animal species, which it sells to veterinarians, distributors, and animal producers. The Healthcare Services segment offers services and solutions that focus on engagement, health analytics, and clinical services to improve the value of care delivered to patients. The Alliances segment includes results from the Company's relationship with AstraZeneca LP related to sales of Nexium and Prilosec.