USDA APHIS requires a veterinary health certificate from the country of origin and mandates quarantine at an APHIS-approved facility upon arrival. The length and conditions of quarantine depend on the horse's origin country and its disease-risk classification, particularly for equine infectious anemia and other reportable conditions.

Mules and hinnies are classified under 010190, separate from horses (010121 and 010129) and asses (010130). The distinction matters for tariff purposes and for APHIS health-certificate requirements, which may differ by species. Consult a licensed customs broker or APHIS for species-specific entry requirements.