Pet Carriers For Air Travel What Dimensions Of Air Travel Pet Carrier Should I Take For A 60lb Pointer/lab Mix, And For A Border Collie?

What dimensions of air travel pet carrier should I take for a 60lb pointer/lab mix, and for a border collie? - pet carriers for air travel

I'm torn) between large (35L 24W 26T or extra large.

Thank you for your advice and comments as appropriate. Who will travel for 7 hours (aircraft)

Thank you.