Comment by tsimionescu
3 days ago
All of the pronoun contractions are somewhat inconsistent with noun possessives. So "its", but "the dog's". There's no reason why you couldn't write "it's" for both "it is" and "its". You already write both "the dog's ball" and "the dog's tired", and both "it's" and "it's" are pronounced identically, which doesn't pose any difficulties in speech.
His, her, and my are a different matter, since they are all pronounced differently from he's*, she's, and I'm.
* at least in most accents, "his" uses the kit vowel, while "he's" uses the fleece vowel
Dog's/dogs are ambiguous. It's/its is not.
"Dog's" is ambiguous in itself (dog is / that belongs to the dog), but this doesn't cause problems in practice. It's exactly the same ambiguity as spelling "it's" for the possessive would give. Also, it's / its is only unambiguous in writing. In speech, they are identical, in every accent of English - and yet people understand each other perfectly fine in spoken English, so the ambiguity is not a problem in practice.