This is personal information and boundaries should be respected. As tempting as it may be to pet a guide dog, remember that this dog is responsible for leading someone who cannot see. The dog should never be distracted from that duty. A person's safety may depend on their dog's alertness and concentration. It is okay to ask someone if you may pet their guide.
Many people enjoy introducing their dogs when they have the time.
The dog's primary responsibility is to its blind partner and it is important that the dog not become solicitous. A guide dog should never be offered food or other distracting treats. The dogs are fed on a schedule and follow a specific diet in order to keep them in optimum condition. Even slight deviations from their routine can disrupt their regular eating and relieving schedules and seriously inconvenience their handlers. Guide dogs are trained to resist offers of food so they will be able to visit restaurants without begging.