price of carrying on a dog

Question
Hi!  I have a silky terrier that I always have to leave behind when I travel.  I saw two people with carry-on pets at the airport, recently.  So, my question is, does it cost extra to carry on a pet, or does the pet just count as one of your regular carry-on itens at no additional charge?  Also, since you travel with pets, which airlines are you aware of that allow carry-on pets.  Thanks so much,
Charlene Hammond

Answer
Each airline has their own policies and they change frequently.  Browse their websites and then call their customer service for much better answers than I can give.  Record the name of the representative you talk to.  It will carry much more weight than Labman.