At the time of writing all the countries you list (UK – France – Belgium – Netherlands – Germany – Austria – Hungary – Romania) are part of the EU. This means that the regulations for travelling with pets are uniform amongst them.

Since you are travelling with less than 5 animals you will have to follow the EU rules for non-commercial movement. Therefore, you won’t need to fill in a Declaration of Non-Commercial Transport form. For information the EU rules state:

Non-commercial movement within the EU

Conditions

In order to be moved into a Member State from another Member State, the following conditions must be met:

Marking – The pet animal (dog, cat or ferret) must be marked by the implantation of a transponder (see technical specifications in Annex II to Regulation (EU) No 576/2013)

Vaccination against rabies – The pet animal (dog, cat or ferret) must be vaccinated against rabies by an authorised veterinarian in accordance with Annex III to Regulation (EU) No 576/2013, as follows:

• the animal was at least 12 weeks old at the date the vaccine was administered,
• the date of administration of the vaccine does not precede the date of marking or reading of the transponder,
• the period of validity of the vaccination starts not less than 21 days from the completion of the vaccination protocol for the primary vaccination, and any subsequent vaccination was carried out within the period of validity of the preceding vaccination.

Treatment against Echinococcus multilocularis – The pet animal (dog only) must, prior to entering Finland, Ireland, Malta or the United Kingdom, or Norway, be treated against the parasite Echinococcus multilocularis in accordance with Commission Delegated Regulation (EU) No 1152/2011, as follows:

• the treatment must be administered by a veterinarian within a period of not more than 120 hours and not less than 24 hours before the time of scheduled entry
• the treatment must be certified by the administering veterinarian in the relevant section of the passport

Passport and declaration – The pet animal (dog, cat or ferret) must be accompanied by:

• a passport (see model in Part 1 of Annex III to Commission Implementing Regulation (EU) No 577/2013)
  • completed and issued by an authorised veterinarian
  • documenting the alpha-numeric code displayed by the transponder or the tattoo, the details of the vaccination against rabies, and where applicable, the details of the treatment against Echinococcus multilocularis.
• a written declaration signed by the owner, in the case where the movement of the animal is carried out under the responsibility of a natural person who has authorisation in writing from the owner to carry out the non-commercial movement of the animal on behalf of the owner, and within not more than five days of the owner’s movement.

Exceptions

Regarding the number of pet animals moved – Where pet animals (dogs, cats or ferrets) are moved in a number of more than five and the conditions to derogate are not met, the animals are to comply with the animal health conditions applicable to trade in the Union.

Regarding the marking – Member States shall authorise the movement into their territory of dogs, cats and ferrets marked by a clearly readable tattoo if applied before 3 July 2011.

Regarding the vaccination against rabies – Member States may authorise the movement into their territory of young dogs, cats and ferrets which are less than 12 weeks old and have not received an anti-rabies vaccination or are between 12 and 16 weeks old and have received an anti-rabies vaccination, but 21 days have not elapsed since the completion of the vaccination protocol for the primary vaccination against rabies.

In that case, the animals must be accompanied by either:

• a declaration of the owner (drawn up in accordance with the model set out in Part 1 of Annex I to Regulation (EU) No 577/2013) attached to the passport stating that from birth until the time of dispatch, the animals have had no contact with wild animals of species susceptible to rabies, or
• their mother on whom they still depend and from the passport of their mother it can be established that the mother received before their birth a valid anti-rabies vaccination.

Regarding the treatment against the tapeworm Echinococcus multilocularis – Dogs moving directly between Finland, Ireland, Malta or the United Kingdom are exempted from the treatment against the tapeworm Echinococcus multilocularis.

Regarding the passport – The movement into a Member State from another Member State of a pet animal (dog, cat or ferret) accompanied by a health certificate shall be authorised if carried out within the validity of such document.