Labrador and Golden Retrievers can usually work until they are 10 or 11 years old. At this point, they might develop problems related to aging that can affect their on-the-job performance. As for Great Danes, who are still fairly new to service work, it’s hard to say.
Carlene White, founder of Service Dog Project, hasn’t seen any of her Great Danes lose their stability yet. One lasted until the age of 14. Currently, she has an 11-year-old dog who is still capable of helping out at nursing homes. She also has two 10-year-olds who are no longer working. Since Service Dog Project has only been around for a decade, she has just gotten to the point where the dogs she bred are at the end of their lives.