There is no way to monitor or assist pets that become uncomfortable or ill during the flight. In fact, due to concern for the health of pets that fly as checked baggage, the US government recently enacted regulations requiring better training in pet handling for airline employees and requiring airlines to notify the Department of Transportation of any adverse incidents involving animals. Also, many airlines now refuse to ship pets as checked baggage during the hottest months of the year, and some, such as Continental and America West, will no longer accept pets as checked baggage at any time. Cargo shipping can be a safer option for pets that must travel by air. Cargo shipments are booked in advance and can be designed for pets' safety, and professional shippers have experience in providing an environment suitable for specialized cargo like live animals.
Some passenger airlines offer cargo shipping, as well as many companies that fly cargo exclusively.
An even better option is a professional animal shipper. Professional animal shippers specialize in keeping pets safe and comfortable while they travel, and some will care for pets all the way from their front door to their destination. For smaller animals, flying as carry-on baggage is a good solution. Most airlines allow passengers to bring a small dog, cat or other pet into the passenger cabin as long as it is quiet, odorless and safely restrained in a pet carrier throughout the flight. This is a good alternative to checking pets as baggage, because temperature and air pressure remain at a safe level inside the cabin, and pet owners can monitor animals at all times for signs of distress.