Okay so that is quite a weird question, but are there any possibilities? And in a natural minor key does a minor v count as a dominant?
A v chord is a chord built on the dominant scale degree (5th scale degree), but functionally is not a dominant chord.
To be a dominant chord, there must be a half step resolution to the root of the next chord via leading tone. For example, G or G7 going to C will have B resolve to C and this resolution is not in Gm or Gm7. This tension and resolution is the basis of functional harmony so it makes sense that a dominant chord must facilitate this kind of resolution to be recognized as such.
It depends on what you mean by "dominant."
In one sense, a "dominant" is just the chord built on the fifth scale degree. And just like tonic chords can be major or minor, just like mediant chords can be major or minor, a dominant chord can be major or minor (even if the minor version is more rare).
A corollary to this is the notion of the "altered dominant." For instance, sometimes composers will make the V triad augmented instead of major (G B D# in the key of C, for instance), smoothing out the voice leading into tonic (B goes by half step to C, D# goes by half step to E).
Other than altered dominants, chords can also be dominant substitutes. In doing so, these other chords have dominant function, though without being a chord built on scale-degree 5. In terms of minor chords, you'll sometimes find iii being used as a dominant substitute, and so in this sense of the word, there you have it: a minor triad that is a dominant (substitute).
Technically, no. But it can be part of a 'cycle of 5ths' progression, where each chord is rooted a 5th above the next. It would be ridiculous to say there wasn't an element of dominant of the dominant of the dominant... in this, even if some of the triads were minor.
Em, Am, Dm, Gm, Cm...
add 7ths, the dominant function is stronger:
Em7, Am7, Dm7, Gm7, Cm7...
And if we make some of the basic triads major, stronger again:
Em7, A7, Dm7, G7, C.
But there's an element of dominant function in the first, minor triads, set, wouldn't you agree?
If you define the dominant as 1,3,5,b7, and the minor as 1,b3,5, you can lower the root by a step and a half to a minor chord (i.e. relative minor) which might be usable as a sub for a dominant 13. Depends on context.
C7 = C E G B
C13 = C E G A B
A minor = A C E