Small dogs often come with a small bark and big bite. Aggression from a small dog can be quite scary because they are nimble and fast, especially when they decide it's time to bite. But your small dog needs to be brushed just like all the other dogs. Brushing a small dog who bites isn't the most fun thing to do, but you can take an opportunity to train your pup to stop biting, at least during this simple grooming task. Remember your small dog who bites does so out of fear or concern for his safety.
If your little guy is nervous or scared or doesn't understand what is happening with the tools you have in your hands, you can ease his tension a bit by taking grooming sessions very slowly. Brush your little guy in small sections and offer him lots of treats along the way.