A stranger smiles and reaches over your dog's head. Your dog lowers their body, turns away, or ducks. You do not need to wait for a growl to intervene. Say, "Please give them some space," and step away with your dog. A greeting does not have to include touch.
Dogs may dislike being approached from above, held still, or touched by someone they do not know. Pain can also make ordinary touch hard. If your dog has begun avoiding familiar hands, flinches in a particular spot, or has snapped, arrange a veterinary check and manage access while you seek qualified behavior support.
Make consent visible
Invite familiar adults to stand sideways at a comfortable distance and let your dog choose whether to approach. They can ignore the dog rather than lean in or reach. If the dog moves away, the greeting is over. When your dog approaches calmly, a brief stroke on a preferred area may be possible, followed by a pause to see whether they ask for more. Never corner them or ask children to test this.
Practice around people without contact. Reward your dog for looking at someone and staying relaxed from a distance, then move on. A dog who walks past people without being petted is succeeding. If they bark, stiffen, freeze, or stop taking food, create more space instead of asking for another try.
You can be polite to the person and clear for your dog: "They're not up for petting today." That sentence is enough. For more on noticing a dog's response and timing rewards, see the dog handling and reward-timing guide. Keep unwanted hands away rather than asking your dog to tolerate them.
Sources: Dogs Trust: How to understand your dog's body language. Dogs Trust: How to handle your dog.