One of the first things you will likely notice when visiting Puerto Rico (and many other islands) are the vast number of stray animals roaming the streets.
The sato is the Puerto Rican word for stray, and there are many that need forever homes.
Several organizations on the island work to find foster homes in the States, and help control the populations through offering free spay/neuter programs for locals.
Satos are the most loyal dogs. You will never find another animal most readily available to offer its love and affection to you forever. It's easy to bring one home with you and these organizations can help you fly them (for free):
Save a Sato: http://saveasato.org/
ARF of Rincon: http://arfrincon.org/
Vieques Humane Society: http://viequeshumanesociety.org/
Just google animal rescue in Puerto Rico to find more.