Strong messages about the life-changing connection and friendship between dogs and their human owners. Also promotes the idea that people aren't meant to go through life alone and that they're happier and more fulfilled with both human partners and animal companions. Clear theme of empathy.
Violence against both dogs and people, some of which could be sad/upsetting. Dogs die from early euthanasia, from being shot and nearly drowned, and of old age. An abusive father pushes his wife and his son, who pushes him back. A scary scene depicts a man who has kidnapped a young girl and is about to hurt her when the police show up. A neglectful owner chains the dog outside and then leaves it alone to find its own way as a stray. A house fire causes a devastating injury.
From the dog's perspective, Ethan and his girlfriend are "licking each other's faces." The dog also mentions that his "butt itches" when Hannah pets him. In another dog life, he falls in love with a female dog.
Infrequent language includes a few uses of "s--t," "dumb," "stupid."
Quite a bit of drinking, particularly by Ethan's father, who starts out drinking socially after work but continues to drink excessively as Ethan grows into adolescence, to the point that he's moody and eventually violent. A toast at a wedding reception.