I've brought a dog in 3 times and a cat in once and never had them quarantined. I think the fine print for BAHA says they reserve the right to quarantine but they'll only do it if they think there's a health issue or if the dog doesn't have a rabies vaccine.
Make sure you get the vet certificate within 7 days of entering Belize (I think the BAHA web site says 14 days but the Belize info my vet had said 7 so we did that to be completely safe) and the rabies vaccine more than 30 days but less than one year before entering the country. Belize does not accept the 3 year Rabies vaccine so even if you're up to date with that, get another one.
Bring copies of your BAHA permit, health certificate and rabies certificate. The airline will probably take a copy and even though BAHA is supposed to be informed of your entry and permit they probably wont be. If you have all the paperwork organized and ready to go the guys in the BAHA office at the airport will be very appreciative.
If you have any problems or concerns, Ms. Melody at the BAHA office is very helpful:
Ms. Melody Robateau
Administrative Assistant/Permit Officer
Secretary for Belize Veterinary Surgeons Board
Animal Health Department
Belize Agricultural Health Authority
Central Farm, Cayo District
Fax: 501-824-4889/3773[email protected]