Live animals intended for breeding require a USDA APHIS veterinary import permit, a health certificate issued by an accredited veterinarian in the country of export, and in many cases a period of quarantine at an APHIS-approved facility upon arrival. Requirements vary by species, origin country, and disease status; importers should contact APHIS National Import Export Services well in advance of the planned shipment date.

When an animal health product's active pharmaceutical ingredient is manufactured in one country but the finished formulation is produced in another, the country of origin for customs purposes is determined by the substantial transformation test. This can affect both the applicable duty rate and whether Section 301 or other trade remedy measures apply. A binding ruling from CBP is advisable when the manufacturing chain spans multiple countries.