There are a variety of airlines that accept pets either in the cargo or even in the cabin so we are going to consider here which of those airlines are the best airlines for pets. Remember, pets include birds, rabbits, kittens, hamsters, or guinea pigs, but these pets do have additional restrictions.
United Airlines - The United Airlines pet policy is that they do allow pets in the baggage and cargo areas as well as in the cabin. Some short-nosed breeds of dogs are not allowed as checked baggage or as cargo during the summer months which are from June 1 through September 30. The breeds referred to are Shih Tzu, Boston Terrier, English Bull dog, French Bull dog, Lhasa Apso , Boxer, King Charles Spaniel, Pug, etc. Heat is a factor here. This does not affect the transportation of pets in the cabin. So United Airlines can certainly be considered one of the best airlines for pets.
Northwest Airlines - The Northwest Airline pet policy is that they are accepted in the cabin on all US flights except Hawaii. They are accepted in some international flights but the airline must be contacted regarding this. Pets are also allowed in the checked baggage and cargo compartments. Northwest airlines boasts to be the industry leader for pet transportation in a safe and efficient manner. So the three options that Northwest Airlines offers for pet transportation are - Cargo Packages (with passenger or traveling alone); Carry-on pets; Pets traveling with checked luggage. Northwest Airlines is one of the best airlines for pets.
Delta Airlines - Delta Airline pet policy is that they accept pets in the cabin, in the checked baggage, and in the cargo compartment. There are restrictions as to what type of pet is allowed in the cabin. They are dogs, birds, hamsters, guinea pigs, ferrets, and cats. The animals that are prohibited include mice / rats, sugar gliders, spiders, pot-bellied pigs, frogs, or reptiles. Delta Airlines boasts safety and comfort for the pet but do have some guidelines for the size, etc of the pets. The pet (s) must fit in a carry-on kennel that fits under the seat in front or the seat the passenger is sitting on. The pet will not be able to travel in the cabin if the flight is going to Hawaii. Lastly the pet must be at least 8 weeks old.
American Airlines - The American Airlines pet policy is that pets are accepted in the cabin and as checked baggage. No more that 7 pets can be booked on one flight in the cabin so it is important to advise the airline ahead of time of the transport of a pet. However, checked pets do not need a reservation. Cats and dogs are the limit of pets that are allowed on the American Airlines.
The best airlines for pets are the four listed above determined by the breath of the policy for the transported pets such as in the cabin, cargo, or checked baggage.