Pets that fly with passengers may be accepted as baggage, paying the corresponding fare, if applicable, irrespective of the baggage allowance which the passenger has a right to.
As a general rule, these animals must be checked-in and stowed in the cargo hold, where they will be placed in a carrier or container which can be acquired in some airlines.
In the correct conditions, they can sometimes travel with their owners in the passenger cabin, provided that the passenger, in addition to the previous requirements, takes responsibility for their care and transport during the flight, without being a nuisance for neighbouring passengers. For this, the maximum measurements of their carrier and the conditions of maximum weight allowed of the animal with its carrier or cage, applied by the airline must be respected, which can be previously checked. Bear in mind that airlines can limit the number of pets travelling in the cabin and may not allow those animals in the cabin which, due to their characteristics, bad smell, etc. may be a nuisance for other passengers and the crew.
It is important that when you make the booking or buy the ticket, whether in the airline or travel agency, you notify your intention of carrying a pet on board and find out the specific conditions for their transport (identification documentation, vaccination, microchip, etc.).
Dogs trained as guide dogs, which accompany an individual passenger, can travel in the cabin, unless national regulations or those of the airlines prevent this. No amount should be paid for their transport, either in the cabin or in the hold. No formalities are necessary in this case, it should just be equipped with muzzle, collar and lead. If the dog flies in the cabin, it will travel beside the passenger in the place assigned by the crew.