Can I use mouthwash to clean my dog’s jowls? Written by Russel in A Can I use mouthwash to clean my dog’s jowls? Though over-the-counter mouthwash is not poisonous to dogs, the high alcohol can irritate the dog’s mouth. Stick to pet approval dental sprays to keep your dog’s mouth fresh. Russel A pet owner who loves to share useful facts and information about a variety of animals.