How many drops of peppermint oil should be put in bottle of dog shampoo?

When adding peppermint oil to a bottle of dog shampoo, it's generally recommended to use 1-2 drops per ounce of shampoo. For a typical 16-ounce bottle, this would mean adding about 16-32 drops. However, it's crucial to consult with a veterinarian before using essential oils on pets, as some can be harmful or irritating to their skin. Always perform a patch test to ensure your dog does not have a negative reaction.