According to Dog Time, Shih Tzus get along well with other dogs. However, like any other dog breed, Shih Tzus require early socialization and interaction, so they do not become timid or scared when other dogs are around.
Shih Tzus are not aggressive dogs. Typically, this breed loves companionship from humans and enjoys the company of other animals. Shih Tzus tend to have friendly, trusting personalities that work well in multi-dog households. However, Shih Tzus that have not been properly trained can develop small dog syndrome, or behavioral issues, that can cause difficulties when introducing another dog into the household.