Bartering services is best reserved for when you were going to make a purchase anyway. So instead of bartering your dog grooming services for an emergency plumber, you could establish an agreement with your shampoo supplier. You know you're going to need shampoo to run your business. So offer to perform a pet pedicure in exchange for an equal value of shampoo each month.
For instance, let's say your pipes burst at your home and you find yourself in need of a plumber. It's an emergency situation and if you don't hire a plumber fast, you'll be displaced and will have to move your family out of the house and into a temporary living situation. That certainly would be a bad thing. But should you barter your dog grooming services right now? Do you really want to trust your plumbing to the only person in town who'll do the job if you shampoo their poodle?