So this is a genitive because of 'нет', right? Otherwise I am lost again
You've got it.
This is sooo John Wick!
What case is собаки? (and why isn't plural accepted)? The dictionary hint only has "dogs" the plural form, which made me do a double take and answer wrong...
It's Genitive singular. The plural would be «собак».
Also, "ваш" would need to be in the plural form "ваших".
Thanks - on that note, the hint is wrong in this case. I'll report it.
It's not a hint it's a direct translation that doesn't take in to account other context. If it were in nominative plural context, it would translate to "dogs"
It's Genitive singular for ваш.
Why not "I haven't got your dog!"?
Should be fine, report it.
What if the dog is a male dog? Does it change the grammar in a sentence like this or it doesn't matter?
I feel like you'd just be able to change the Вашей to Твоего/Вашего assuming you're trying to use пёс and then of course add the ending. So perhaps it'd be "У меня нет твоего пёса"??? Could use the opinion of a native but that's what I'd assume.