Where is the merck animal health headquarters located? Our Merck Animal Health headquarters is located at: 2 Giralda Farms Madison, NJ 07940 U.S.A. Contact information for Stockholders and Investors is available her e.How do i contact merck animal health for after hours emergencies? For after-hours emergencies: Call the appropriate number listed above and follow the prompts. For information about Merck Animal Health products, call Animal Health Customer Service: 800-521-5767.How do i contact merck customer service? Just call us at 800.672.6372. Thank you for visiting. Merck does not review or control the content at the site to which this link connects. Merck makes no representation with respect to the content of any non-Merck site.How do i report an adverse reaction to merck? To report an adverse reaction, product-related problem or human exposure, please call Merck Animal Health Technical Services. For information about Merck Animal Health products, call 1-800-521-5767. For technical assistance or to report a suspected adverse drug reaction, contact Merck Animal Health at 1-800-224-5318.