What should be done with the dirty dog?

The appropriate action concerning a dirty dog is to bathe it. Bathing is a necessary step to clean the dog's fur and remove any dirt, odors, or parasites that might be present, ensuring the dog's health and hygiene. It also enhances the bond between the dog and its owner, as grooming can be a comforting experience for the pet.

Leashing, feeding, and walking are important aspects of pet care but do not directly address the specific need of cleaning a dirty dog. Leashing is primarily about controlling the dog during outdoor activities, feeding is related to providing nutrition, and walking helps in exercise and relieving the dog, but these actions do not resolve the issue of the dog's dirtiness. Thus, bathing is the most suitable choice in this context.