It's not negative, it's not Photoshop, the rat is not frozen. Blue color of this rat's skin may be the secret to avoid spinal cord injuries and paralysis.
The scientists took rats with broken spinal chords and injected them Brilliant Blue G dye, a variant of common and harmless food coloring product. The dye turned rats skins blue, but within weeks all motor functions returned to normal. The rat could walk, run, jump, have sex, and do whatever it wanted.
From here or here.