This may be old news, but just to be sure . . . . In the "old days" my mobile vet used to groan at the idea of doing bloodwork for ACTH . . . specific tubes, refrigeration until spun, etc. And I used to put the samples on ice and take to the clinic for him. He now uses a kit which contains everything needed, including a cold pack. As long as he has a kit on his truck, no problem. I've never asked where he gets these, they are pre-packaged, self contained. My first guess in looking for them would be Cornell, as that's where he sends the samples. Is it possible that your vet hasn't found these yet and if you could show him an easier way it might help? If one of his problems is that he has to get back home and spin the sample himself, could you find a nearby small animal clinic that might do that part for him?