What do you do when unleashed dogs approach?

i stop moving forward first ... if the owner is close enough to hear me, i call out my dog has kennel cough and to keep their dog/s back ... if the dog continues to approach i use my foot to keep it back ... if the owner has a problem, i would just my foot on them too :O) if the owner is not close enough i will let the unleashed dog go nose to nose with mine and then when i catch up with the owner i suggest a vet visit because their dog just went nose to nose with my actively infected with kennel cough dog (my dog has never had kennel cough) ... that really ticks them off :O)