Besides having a fully valid passport, Children follow the same restrictions and rules as adults concerning travel.
Pets are slightly trickier; first you are advised, although not required, to have your pet microchipped. Following that, any pet over the age of three months old must have a rabies certificate and the animal must have been vaccinated at least 60 days before you depart but not over one calendar year before.
You will also need a standard healthcare certificate issued within ten days of your flight (US: Vet Health Certificate 7001, UK: PETS) which is signed and stamped by a qualified vet and must contain the owner’s name and address, the animal’s description, breed, date of birth, sex, size, colour and unusual features as well as country of origin and transit points. Quarantined pets are expected to be fed and cleaned regularly by the owner.
You will also require an import permit from the Ministry of Agriculture in Brunei if you intend to import a dog, cat or bird.
Unless brought into the country from the UK, Republic of Ireland, Australia, New Zealand, Singapore, Sabah or Sarawak, the animal will be quarantined for 180 days.