The only official word on them was a release back in Ought One and all it said was that if you see one let us know and that they are officially classified as "Feral Domestics" so its ok to shoot them w/o a licence.

So it is entirely plausible that it is a just a rumor.
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The art of government is to make two-thirds of a nation pay all it possibly can pay for the benefit of the other third.--Voltaire