Kendall,

They charge you the extra money because Seamus is taking up cargo space and adding weight to the plane. And if an animal dies, they will pay you whatever the animal is "worth" (crass as that sounds), with a cap on the value of the animal, although I'm not sure if that cap is a uniform amount or if it varies from carrier to carrier. So they are "responsible" in that they'll pay you money for your loss. It's like if they smashed your guitar or your laptop--an animal, sadly, falls into the same category.

But really, I'm relieved you've decided not to go that route. Chances are, of course, nothing would happen but you never know--it definitely does happen--and if there's any other way, why risk it? You'd be a big bundle of nerves during the flight anyway, worrying about dear Seamus. (You'd be the one who'd need the sedative!) And as you know, doggies are wonderful--I'm sure he'd do the same for you. :)

And besides, he can stick his head out the window of the car and let his ears fly like the wind!