From the Journals of Commander Septimus Tiberius

In my journeys across the Imperium I took my ship, the Camazotz, to the territories of The Canid Tribes. A hunter's ritual I had the pleasure of engaging with is the Winter Wolf sacrifice. The ritual requires a wolf or dog of snow white coat. There are various methods for procuring one but cloning has become the favoured way. I will explain why in a moment. Volunteers are accepted. Unwilling captives often make good hunts. Regardless of their origin, to be a Winter Wolf is considered a courageous honour and they are treated with considerable respect. Many groups will travel with one or several in their pack case they need to complete the ritual while they are abroad.
 Special worlds are chosen for this, often planets of eternal cold are chosen as centres for the production of Winter Wolves, as well as facilitation of the ritual. Great boreal forest flourish unchecked, and in these wilds the ritual itself takes place.
When possible the Winter Wolf is hunted by groups no more than two dozen. When brought back to the tribes' camp, the Winter Wolf is then tied to a garrote post, where each man who participated in the hunt twists the garrote tighter until the wolf is as they say "Gone to Anubis." (A tribal death god with a canine head). A long fight against the garrote is considered honourable.
The reason cloning has become the favoured way is because both before and after the sacrifice the Winter Wolf is effectively a revered consort. During life the Winter Wolf is hosted by tribal leaders who are the only ones permitted to fuck the mongrels.
The last person to be permitted unrestricted access to the Winter Wolf's body is the hunter who caught him. After the sacrifice is complete the Winter Wolf is used by those who participated in the hunt. Once everyone has filled it with semen, the Winter Wolf is returned (usually in a ceremonial shroud) to the Canid gene farms, where they use the biomass to grow the next Winter Wolf. The introduction of sufficient genetic matter prevents the cloning pattern from degrading. To see your own genetic traits in a Winter Wolf is considered good luck, if you're the one who catches him. In this way the Winter Wolves can be as much part of their respective tribes as the hunters who chase them.
I have seen and participated in several winter sacrifices and have seen a variety of styles done but regardless of circumstance the Winter Wolf is always strangled with a sacred rope or cord.
I am going to recommend a secular form of this ritual for use in the Imperium's military. I believe it will help with morale. Regardless of it's acceptance, I fully intend to return to Canid territory to participate in this ritual for every Winter I am able.