In re the various hypotheses presented thus far:
1 I was under the impression that the heart-spot was artificial, and therefore
not necessarily permanent, but then purple cats, so ... maybe.
2 At that proximity, Fox should be more than capable of identifying her by scent.
3 The state of her eyes looks like
miosis, which would suggest that she may have been poisoned or drugged, although I wouldn't eliminate possession as a possibility.
4 There would be no point to the pink husky causing all of this, as it would be an absurdly roundabout way of doing something she could easily accomplish with the same powers.
5 Milton's biological heirs would have little to gain from assassinating Keene alone. It could only be profitable if they killed off all of the ferrets in one go, and even then they'd have better odds waiting for them to die naturally.
Really, I get the feeling someone running the obedience classes set Sasha up for this. They obviously didn't make her obedient to Mr. Hartford, and organizations dedicated to subverting the will of domesticated animals would not fare well if those animals were granted equal rights.