Flying Southwest Airlines with a dog?

I am asking this for someone else. Any advise/info would be greatly appreciated.

" In less than a month me and the family will be traveling from San Fran to Chicago for 3 weeks and we will hopefully be taking Daisy our 1 year old Cairn.  I was hoping someone on here would be able to share there specific experience of flying Southwest Airlines.  We bought a airline approved container (soft med Sherpa) bag for her and she fits just fine. She can stand up and turn around but, once under the seat she may not be able to stand?  She is 14 lbs and a very calm traveler in the car. I keep reading conflicting stories of people who say I shouldn't have a problem and some people say they were turned away because the pup  appeared too cramped.  I already contacted Southwest and the person I spoke to told me that I "should" be ok.   So what I'm getting is that, whether your pup is allowed depends solely on the person at check-in and how they perceive the size of the dog."

Any experiences or advise?  Thank you!

Slightly different scenario, but I flew southwest with my TWO cats in ONE carrier.  Southwest allows that and I knew mine would be happier together.  That was a 9 pound cat and a 6/7 pound cat in the Sherpa carrier.  So a minimum of 15 pounds crammed in there.  No problems with Southwest at all.

Hi KFdancer - thanks for the reply. Do you know offhand what size carrier you used?

oh really ?