It's not clear if you intend to have the cat on St Lucia
for a while, or will go directly from the airport
to a boat
. That can possibly make a difference.
If you're flying in with your cat and plan to immediately go to your boat
, and the cat will never be allowed to touch St Lucia's soil, I believe that you can claim that you're not technically "importing" the pet. You need to get in touch with the government's chief veterinarian to try to sort this out. You may very well find a way to make it work
Alternately, flying in to St Thomas is hassle-free, which is what my wife did when she and our cat came to meet me in the islands. She flew AA and carried the cat in a soft carrier that fit under the seat.
Once the cat was on board, we sailed to all the islands in the Leewards and Windwards but three, and never had any problems with Customs
and Immigration on the rabies-free islands when we declared our cat and stated that she always stayed on board. However, when we moved to Nevis
to live there full time, we had to go through all the onerous pet-import procedures designed to keep rabies out of the island because in that instance we were truly "importing" a pet.
p.s. airlines that allow pets in the cabin
do limit the number on board, so make your reservation early. They also charge a fee, even though the pet rides under the seat for takeoff and landing, and in your lap during the flight (always in the pet carrier).