In this Monday, Nov. 6, 2017, photo, research technician Kelsie Condon walks a Golden Retriever named Zach on a treadmill to determine if the dog has arthritis and can be enrolled in a study involving the use of CBD oil at Colorado State University in Fort Collins, Colo. Two researchers at the school are running trial studies to see if using marijuana extract aids in the treatment of dogs with epilepsy as well as arthritis. (AP Photo/David Zalubowski)
