Animal protection shelters will help you identify and locate the owner or check their health and relocate in case of abandonment.
If you see a dog or cat without a collar, or identification and think it is lost or abandoned, what should you do? In these cases you can notify the local police of the municipality of the place where you found it, or pick it up yourself and take it to an animal shelter to examine it and be able to locate it's owner or in case of abandonment deworming it and relocating it to find a new owner.
It is possible the lost animal is scared and elusive and does not respond to your calls. How to get close to him? Until help arrives, to keep him calm and visually controlled, talk to him softly and calmly without looking into his eyes. Do not approach directly in a straight line, always keeping the distance approaching in a very slow circle. If you shy away from the approach you can turn your back watching him sideways to keep him under control and don't escape.