Which of the following is an activity performed only by accredited veterinarians?

The correct answer is performing certain tests on animals on behalf of USDA-APHIS, as this task requires specific accreditation and regulatory compliance that only licensed veterinarians possess. Accredited veterinarians play a crucial role in ensuring the health and safety of animal populations, particularly in the context of public health and biosecurity.

In the context of the activities mentioned, certain tests may involve regulatory oversight, particularly those related to disease control and prevention, that require a veterinarian to be accredited with the USDA's Animal and Plant Health Inspection Service (APHIS). This accreditation involves meeting specific educational and ethical standards necessary for conducting tests that might impact both animal and human health at the national level.

While issuing prescriptions for veterinarians also necessitates being a licensed veterinarian, the phrasing implies a role that could attract confusion regarding who is actually prescribing the medication. Additionally, performing general check-ups and administering routine vaccinations, though important, are more common practices that can be performed by veterinarians without the specialized accreditation required for USDA-APHIS testing. Therefore, these activities do not reflect the exclusive responsibilities tied to accreditation.