Things to consider with pet travel via cargo:
If the temperature of any airport on the itinerary exceeds 85°F or falls below 40°F, the pet will not be allowed to travel via cargo.
Some airports such as Houston and Atlanta will not allow a pet to travel via cargo during the hotter parts of the year.
Some airline carriers will not allow pet travel via cargo if the flight exceeds a certain amout of hours.
Most carriers will limit the number of pets allowed to travel via cargo.
Some airline carriers will not allow a pet to travel during certain times of the year due to headwinds.