Unless the skin is severely freezer burned,You should be fine. You may want to try a relaxing agent when you rehydrate only because of the length of time it was frozen. Slippage is usually caused by bacteria... that being said try not to soak it too long . Will you be tanning it yourself or sending it out?? I have tanned bears that had been 8 - 10 years frozen, but they had not been fleshed ( the fat protected the skin some from freezer burn). Your cougar probably doesn't have much fat on it. Hope you can salvage a nice animal. Dry the ears & face as well as you can after tanning or soaking (helps prevent slippage)
