I have not arrived by boat with a pet but I worked in Batangas Philippines
for two years with several people who had their dogs
with them. All they needed was a health
cert. to enter PI showing all their shots. To leave after an extended stay (1 to 2 years) was another health
cert. That may have been required to enter the U.S.
The cost was around 1000 to 1500 Peso ($20-30 U.S.) Finding the vet to issue one was a little dificult as I recall
. Be sure your pet is up to date because most there have not had any!