You are asking a question on SWA's community forum and, most likely, will not receive an answer from SWA.
The pet carrier that you are considering is a bit risky to me, especially with the height. It must completely fit under the seat in front of you.
SWA allows pet carriers that have maximum dimensions of 18.5" (L) x 13.5" (W) x 9.5" (H).
Yours has dimensions of 19.5" (L) x 12" (W) x 12" (H)...exceeding both the length and height maximums. Officially, it's too large. Will they be that picky at the gate? Can you mash down on the height with Fido inside? YMMV and it will all depend on the staff that day...and on your return trip.
Remember, your dog/cat must be completely inside the pet carrier and be able to stand up and move around the carrier with ease. Yesterday, I actually saw the gate agent confirm that the dog has enough space in the carrier. I had never seen that checked before.
IMHO, I wouldn't risk being turned away with a pet carrier that exceeded SWA's dimension limits. Either purchase the one the SWA sells or find one that's a bit smaller.
Good luck!
