Have you checked the airline website - they usually post the requirements for on board kennel size. It does need to sit beneath the seat.
Sometimes the measurements are different if you use soft side versus hard crate.
the height is most restrictive as you can imagine. Just look at the distance to the underside of the seat and that is the height you have to work with. Not probably more than 12 "
I travelled with my Razz in a purse type carrier. It was great easy to sling over my shoulder and fit under the seat. It wasn't more than 10" high and about 14" long.
Gail in ONtario |