This is not grammatically correct, in English at least. There should be a full stop, not a comma!
Yes, the comma splice error threw me off. To make the sentence correct, I added "and" after the comma. Duolingo frowned on that kind of correctness.
How do Italians use semicolons and periods? I'm confused as to if this is correct but awkwardly written for English speakers, or if it's just incorrect.
There is actually no equivalent for pet in Italian, they're indicated by combination of words as "animale domestico", "animale da compagnia", and similars; but those names are used only when necessary, most often one just says animal(s) and you can guess by the context.
So would it be correct to translate this sentence as "I have a pet, it's a mouse."?
I'd say so, yeah, at least in informal speech.
That sentence is a bit weird...does any other translation than "pet" make sense here? Usually you'd either say "I've got a [insert animal here]" and it would mean "as a pet". To say something like "I've got mice" generally translates as "Yuck! Got vermin in the house, it's mice" Never heard anyone say something like "I've got an animal. It's a tomcat" O.o
'Mouse' :P The English word is used as a loan to mean just that.