Her continued mental resistance to the changes was a good sign, believe it or not - previous trials had demonstrated that a strong mental fortitude was necessary for the required mental capacity to survive the process. Hostility from the subject was likely once the process was over but preserving sapience was a desired end goal that had not been accomplished in previous trials, which usually ended with either a barely-coherent creature that proved too difficult to deal with and had to be put out to pasture or one that did not take the equine characteristics and thus wouldn't serve the intended purpose. In this female's case, the high-pitched squeal indicating horror that was emitted upon noticing her sex beginning to thicken in addition to its continuing growth lengthwise, the continual turning of her head to look at failed attempts to break an arm or leg free of the restraints even after muscle had begun to show visibly on them, and the muffled shouts of which the tube attached to her mouth had prevented from making clear (though the cadence of the noises and the angry look on her face suggested there would have been many invectives) all indicated the continual presence of human-level mental sapience. This is despite the spread of the black coat of fur now from the midpoint of her chest to the top of her thickened knees, the sprouting of a dark-colored tail from the base of her spine, periodic glossing over of her now nearly-completely-black eyes, and increased touch sensitivity from her breasts and nether regions against the tubes delivering chemicals (the former two being outward manifestations of the stallion-related chemicals, the latter two previously-identified sources of potential mental weakness that could compromise the female's mental fortitude).
Speaking of, it would be at this point that the most dramatic physical changes would take place, marked by the introduction the Stage 2 solution. Her eyes would widen as she notices the fluid in the tubes change from white to...