Choosing the right size toothbrush is essential for effectively cleaning your dog's teeth and gums. For small dogs, choose a small toothbrush that is easier to maneuver and can easily reach all areas of your dog's mouth. For medium-sized dogs, choose a medium-sized toothbrush, while larger dogs will need a larger toothbrush to accommodate their larger mouths. The design of the toothbrush should fit the shape of your dog's mouth to allow for comfortable brushing, as well as making sure that the bristles are soft enough to avoid hurting your dog's gums. The condition of your dog's mouth should also be taken into consideration when choosing a toothbrush; if your dog has tartar in his mouth, choose a soft-bristled brush, or a hard-bristled brush if his mouth is already clean. The correct size and design of the toothbrush will help to improve the efficiency of brushing and the dog's acceptance.