Is there any information that MUST be included on the certificate that my vet writes for our pet?
Actually, yes. First, make sure that the actual dates of vaccination appear on the health certificate! According to the USDA, your certificate for each pet must...
Where do I show this information at the border, or turn it in?
When you get to your border crossing, look for a sign that reads: "Aduana." In Spanish, this means 'customs office.' You will show your documents to Mexican Customs officials at the aduana.
Be prepared for customs officials (in both directions) to visually inspect your pet for signs of disease before giving you clearance.
Is it possible to get an International Certificate of Health and proof of vaccinations for my pets while I am in Mexico?
Yes, it is. For a small fee, you can get a Certificado Zoosanitario from a licensed Mexican veterinarian proving recent vaccination for rabies, triple canina and parovirus. Remember that at least 30 days must pass after your pet is vaccinated before you may enter the US with it, or else you will have to place it in quarantine. The Mexican certificate of good health must indicate that your pet has been thoroughly checked out by a vet within the month (30 days) prior to your re-entry and clearly state that your pet is in good health. Any health certificate older issued more than 30 days before your re-entry will not be accepted.