I have the impression, "hangi" implies the accusative suffix for the corresponding noun like a definite article would (if there was one) - given it appears in an accusative clause - since in that construction you are also talking about a specific instance, even if you obviously do not know, which one. Is that correct?
"see" is one of those verbs that are usually not used in the continuous aspect in English in certain meanings.
We say, "I see the mountain!" (not: I am seeing); "I have a fever" (not: I am having); "I feel good" (usually not: I am feeling); "I believe you" (not: I am believing); "Do you understand this sentence?" (not: are you understanding).
Not quite certain how this would apply to a dog, but there is "to be seeing" in English, but always in an idiomatic sense, as far as I know. Like "to be seeing things" meaning "to see things that aren't actually there / to see ghosts", or "to be seeing somebody" meaning "to have a romantic/sexual relationship with somebody".
It could also be used by a veterinarian's assistant who asks "Which dog are you seeing?" When you have an appointment with someone, you are seeing them. It's perfectly acceptable in English to use the continuous "seeing" in many circumstances.