My dog keeps coughing likes he's choking?

My toy poodle is 12 yrs of age, and thats probably why he is coughing. He is coughing very harshly then gagging like he is going to throw up something but he doesnt. It might be of old age but I need to know if we should take him to the vet. Or if hes in pain. Hes a happy dog, playful like hes young. He also breathes heavy enough for us to hear in his sleep.