There's a pet shop in Pasir Ris Farmway...can't remember the number, Pet Movers, that's the name of the shop, they help with such services.
Check out their website
http://www.petmovers.com.sg/
Do you really want to bring your retriever to HK? The apartments here are really small. And the hong kongers are not as dog friendly as Singaporeans. I miss my maltese as well. Toying with the idea of bringing her here