Direct answer: Yes, mice are generally wary of dogs and will often retreat when a dog is present, but a dog alone is not a foolproof solution for preventing or eliminating a mouse infestation. The effectiveness depends on factors like the dog’s breed, temperament, and training, the presence of other attractants (food, crumbs, pet waste), and whether the mice are highly motivated to stay in the area. In practice, dogs may reduce activity temporarily and can contribute to deterrence, but mice can still persist or return if other conditions invite them. If you’re dealing with a mouse issue, a multi-pronged approach tends to work best:

• Remove attractants: store food in sealed containers, clean up crumbs, fix leaks, and seal entry points.
• Improve surveillance: set up and maintain mousetraps or deterrents where appropriate, and consider inspecting for nesting sites.
• Consider integrated pest measures: combine humane traps, traditional snap traps, and professional recommendations as needed.
• Maintain pet safety: ensure that dog food is stored securely and that any dog odors or pheromones do not attract mice in other ways.

If you’d like, provide details about your setting (indoor/outdoor, severity, dog breed, presence of other pets, and available entry points). That will help tailor practical steps to your situation.