Chihuahua is only 3-5 pounds in weight and considered the smallest breed across the world. This is the most common reason that people prefer Chihuahua over larger dogs.
General issues with Chihuahua and other dogs: The threat of injury is the major problem when you raise the Chihuahua in the presence of other larger dog. If the dog is more powerful and larger, then the attack may result in a serious life threatening injury to the Chihuahua. During feeding, the fight is obvious between two dogs and if one dog is weak and small then there are more chances of injuries.
Socialization: In order to develop social skills which are very important to interact with other people, you need to socialize your dog in an early stage so it will be exposed to people and other dogs as well.
Supervision: Supervision is very important if there is one larger dog with the Chihuahua. Initially, the larger dogs have no idea that how to deal with small Chihuahua but gradually affection will grow for the small companion. If they are playing in the same room then supervise them to avoid any kind of harm or injury.
Feeding time: Many dogs protect the food by lashing out in an aggressive manner to frighten people or other dogs but it is not a healthy response. Such dogs that show aggression at the time of feeding usually do not eat in a proper way. The best way to feed your dog is to provide two medium-sized bowls on daily basis and if there is still confusion about the food quantity then talk to the experienced veterinarian and select the appropriate amount of food for your dog. To avoid aggression, provide food to dogs in different locations of the house. For instance, if a larger dog is feeding in the kitchen area then give food to your Chihuahua in the room.