They’ll let you know. My dog has moods, each has their own body language. Sometimes she wants head and ear scritches, so she’ll bump her head into my hands and keep them there until I start petting. Sometimes she wants belly rubs, she will roll on her back in front of me or on the couch/bed. If I ignore her, she will switch positions into my line of sight and repeat. She also sometimes is not in the mood for petting, and my approaches will be dismissed. She turns her back and ignores me. She learned to signal her walking leash all proper and formal on her own when she wants to go for a walk. She sits in front of the leash pointing with her snout and waits until I notice. She will bark if I’m not around to call my attention.

Sometimes I stop on purpose to see her reaction. If she’s okay with stopping the activity she will leave or regain a neutral posture. If she wants more she will tap me with her paw until I resume. It’s very cute. Dogs are definitely very communicative if they want something.