Doesn't the subject go at the end? I got it all twisted up with "Inu ka waiū i kāua."
Hawaiian is Verb-Subject-Object order. The i comes before the object to mark it.
Okay if This is not milk is he then why isn't this sentence Inu kāua i HE waiū?
Because kāua drink milk, in definitive. The sentence wouldn't make any sense if milk was indefinitive.