am I supposed to tip the dog sitters?

Tips and/or gifts are always appreciated, but there is no obligation to tip. Other ways to express appreciation of your sitter are: write a great review, refer other pet parents, and book often.

You are never obligated to tip your sitter but if you feel you the service you have had from your sitter is tip worthy, I say go right ahead. I myself as sitter always appreciate when a client feels I deserve a tip but I never expected it and I don't think a client should feel the need to give me anything above my regular fee, I treat all dogs and owners the best I can, tip or no tip.

When I would see a client feel the urge to tip is if their dog required more than usual like being brought to the groomer by the sitter or the sitter needing to run errands for their dog, or if the owner was very late on pick up or if things changed a lot during the stay, that sort of thing.