We bought our tickets on Jan 17th with United.
We just booked ours with Iberia, I was going with Lufthansa first, but turned out Iberia is €400 cheaper and takes about the same time to get to BsAs from our departing point.
We have one 3-hour stop in Madrid, and we will have to pay €150 to bring our cat in cabin with us.
I have to say you have juggle a little between call centers to get a fair rate, the cat reservation and your seat booking.
We called Iberia's Argentinian booking line and they quoted us 22.000 pesos one way, but added that if we booked online it was cheaper. Hell, I knew - online was €722! They said the cat would fly for €150 all the way.
Next day we booked online for ourselves, then called again the Argentinian number to book for the cat and they said it was €300 (€150 per flight), but when we replied they said €150 the day before, the lady "checked" and agreed that €150 was the correct rate. I have to say that about the rest of the details they were thorough, they asked for the size of our cat carrier,how much the cat weights, the total weight cat+carrier - we told them it was even with a flexible height and the brand (SturdiBag, model Large). I read SherpaBag is cheaper and widely accepted, but it is not sold where we are.
Also, online we were asked €30/seat to reserve a seat of our choice, but when we reserved through the Argentinian booking number we had them both for free. We are looking toward a 18:15 hr trip, not counting the check-in and check-out times at the airports.
I am a little worried about keeping Pippi caged the whole time, but we have no other choice and after all it is just a day.
I am researching on how to feed her water while traveling, since soft carriers have no hooks where you can hang on feeders.