Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to clean your dog's teeth [title] Buy a dog toothbrush and toothpaste. [step] Do not use human toothpaste or toothbrushes to clean your dog's teeth. Human toothpaste contains high amounts of fluoride, which is poisonous to dogs.

Ending1: Take care when using human toothbrush and toothpaste to be gentle enough to avoid the dogs mouth. [title] Choose a toothbrush that is actually made from animal-derived bristles. Ending2: Visit your local pet supply or pet grooming store to purchase dog toothpaste and a toothbrush. You can also make your own doggie toothpaste by mixing baking soda with water. Ending3: It is highly contagious, causing sore gums. [title] Provide your dog with a regular brushing. Ending4: Your dog will also typically have an unpleasant flavor when used unless you thoroughly check his teeth to avoid acid contamination. For this reason, it is better to buy a toothbrush specifically designed for dogs with braces or a dental scrub instead.

Answer format: ending1/ending2/ending3/ending4