Owning multiple Chihuahuas requires more time and vigilance in handling and closely observing each dog every day. If a Chi is off her feed, there's likely to be something wrong. If you feed each dog separately, you can spot a loss of appetite immediately.

Other warning signs of illness are harder to observe in a group canine environment, such as individual water intake, vomiting, diarrhea, or lack of bowel movements. With water intake, copious amounts of drinking could signal diabetes or another disease. If your Chis drink out of a communal bowl of fresh water, you may not pick up on this very quickly unless you make it a habit to keep an eye on their drinking habits.

A problem with a dog's gastrointestinal tract is easy to spot, but unless you actually see the Chi vomit or defecate, you'll have no idea “whodunit.” Again, the only way to determine which dog did what is by close observation.