Anticipating a professional philologist's answer, I'm just pointing out you got the construction slightly wrong. Ὑπέρ is "beyond", "trans", but normally in a sense of excess, that is "more so", as in "hyperplasia"; not opposition, "so far beyond to effectively negate", or "beyond the reach of", as ...
The word for empty in Greek appears to be κενό, ultimately from Proto-Indo-European *ḱen-.
The word for dog, κῠ́ων, is from Proto-Indo-European *ḱwṓ. (This would make it cognate with English hound, Latin canis etc.)
So there doesn't appear to be any common ancestry between κῠ́ων and κενό. It's not surprising given the lack of semantic connection.