Here's why I'd never invest in the Uber for dog walkers: Once someone finds a walker they like, they'll just do a deal with them. Dog walking isn't like needing a ride. Usually when you need a ride, you need it now, and you don't care who provides it. With dog walking, it's usually at a scheduled time each day, and you care a lot about who is providing the service. Dog walking is not a good candidate for the Uber mod…
Rover.com is doing pretty well [1] with a similar service. In my area at least, these dog sitters (and, I assume, these dog walkers) are young, and take it on temporarily as an alternate source of income. They may not stick around for long, and you'll soon be looking for another. Also, their schedules may change frequently - your preferred walker/sitter may not be available on the date of your vacation or other cause…
As soon as she builds a relationship with the person they transact outside the app.