Since every dog is different, the conditions and degrees of this might vary, but all dog parents should be aware of it. Like people, dogs display stress in various ways.
Fair enough, digestive issues are hard to diagnose. Dogs don't eat like humans, so digestive troubles might mean anything.
Aggression is always a problem, but if it appears aimed towards a person or animal, it may be advisable to eliminate the source until a better solution is found.
Some claim dogs are unpredictable since they can't communicate with their families. Not entirely true. Dogs communicate in unique ways that experienced dog parents can recognize.
A housetrained dog going pee inside is another indicator of stress. A few times is OK, but if it becomes a habit, it may be worth investigating.
Something may be wrong if your dog sleeps more or less. Stress disrupts dogs' sleep schedules like people.