Here is the link to get the Third Country Vet Certificate
http://www.aphis.usda.gov/NCIE/iregs/animals/no_cn_hc.pdfYou can also get it here on the DEFRA website. It is at the bottom of the document.
http://europa.eu.int/eur-lex/pri/en/oj/dat/2004/l_065/l_06520040303en00130019.pdf Also: it must be printed on one sheet of paper (double sided). It will not be accepted if it is on two sheets of paper
The serial number at the top of the certificate must be issued by a USDA certified (government) vet upon their approval of the Rabies Titre paperwork and the completion of the certificate up to the Tick and Tapeworm treatment. The animal does not have to be present.
Recommended time line to have the USDA approval is 7-10 days before departure. The clock on the 4 months grace period after the quarantine is up starts ticking the moment the serial number is issued.
For Canada, here is the link for the Canadian Food Inspection Agency for Exporting Animals to the UK
http://www.inspection.gc.ca/english/anima/heasan/export/petcom/ec_ce_uk_infoe.shtml Other important information: The tick and tapeworm treatments must be done 24-48 hours before departure. Make sure that the vet writes out the date in full (not numerically) and writes the TIME in 24 hour format. This is where most of the slip ups happen, according to the people at the animal reception centre at Heathrow.
