HI Pieroban.
I"m looking at bringing my dog to Port Moresby. We are also looking at bringing our dog (3 year old labrador retriever). From the research I've done, the PNG RSPCA () has vets and they also have a boarding facility.
With pet food we will be bringing our own as we get a shipping container.
The import process for dogs is quite difficult. I believe you can only import dogs into PNG direct from certain countries (Australia, NZ..and i can't remember the others).