Translation:I have never seen a talking dog.
Although "speaking dog" is accepted, "talking dog" is more natural in US English.
Yes, it would make sense if used in your particular example. I was simply explaining why 'had' doesn't work in the asker's translation of "Я никогда не видела говорящую собаку". This statement in Russian requires the use of 'have' rather than 'had' as it is implied that the speaker has never seen a talking dog, whereas 'had' would imply the speaker had never seen a talking dog until the point at which he said the sentence.
The perfective often expresses the idea of results or completion; so if something never happened, it makes sense to use the imperfective. In general it's common to use the imperfective with negation in the past, unless something expected didn't happen:
Он никогда не приходил (imperfective) к нам. He never came to see us.
Вани не было? А почему он не пришёл (perfective)? Vanya wasn't there? Why didn't he come? (he was supposed to, I thought he'd be there)