Adopting a pet in Puerto Rico

It is more likely that a stray dog will adopt you than the other way around. 

There has long been a terrible stray dog problem in PR, though at least by my observation it is not as bad as it was five years ago.  There are a number of rescue organizations that have been collecting strays and shipping them north for adoption. Save a Sato, the Sato Project, All Sato Rescue are a few.  There are also numerous shelters brimming with animals. And there are many just roaming the streets.

Ours found us.  Chewed up by a pack it showed up in bad shape.  After a significant contribution to the local veterinary economy, the dog is great and won't leave my wife's side.

Taking any pet on an airplane is a challenge.  JetBlue will let you take a small pet <20lbs in the cabin for $120 and that works great.  Other airlines are not so pet-friendly.  Ours is 30lbs and has to go in a crate in baggage and that is a royal pain with lots of complications relating to heat restrictions, drop off locations, etc.  From a paperwork point of view, you will need a recent health letter from a vet that is easy to get. The fares for the animal are usually more than yours.