Is it dangerous to fly an 18-month-old mini Yorkshire Terrier in an 8-hour pressurized cargo hold?

Flying a pet in a pressurized cargo hold is like a normal hold but with temperature, pressure and oxygen equipment. Prepare in advance and let the dog adapt, and tell the crew to remind the pilot to switch on the oxygen, which lowers risk.

But no risk is zero, since plane faults can occur and a timid or low-immunity dog may still have an accident.