I hate to bust everyones bubble but, ALL pressurized commercial airlines cargo holds ARE pressurized. They may not be heated but, there are pressurized. Within an airplanes cargo hold are fire suppression systems. If you had an unpressurized hold ,the fire suppression system would be unable to work, as you would be unable to keep the suppression agent in the plane. There are also other reasons that they are pressurized, one of which is that the floor underneath your feet on a plane is not made to withstand a pressure differential. On a pilots preflight, there are told if there are any live animals in hold . Usally a pet will be put into a forward hold and the the pilot must activate the heat in the hold. The switch is usally termed "puppy snuffer". Temperatures in unheated holds can reach as must as -50 centigrade with no air flow. SO, Wrap you cans in towels, put them in the middle of your suitcase and, hope that no baggage handler tosses them off the back of the plane to the runway when unloading them.