Which time frame of the animal's health status is revealed by serological tests on samples taken when animals arrive at the facility?

• A. Health status upon arrival at the facility
• B. Health status when they left the vendor's facility
• C. Health status 2 weeks before shipment
• D. Health status 4-6 weeks prior to arrival at the facility

Answer: (C)

Serology looks for antibodies that the immune system makes after exposure to pathogens. There’s a delay between infection and when those antibodies reach detectable levels, called seroconversion. When samples are taken at arrival, the antibodies you detect generally reflect exposures that occurred in the weeks leading up to shipment. In practice, this means about two weeks before shipment is the most reliable window captured by arrival serology. It indicates the animal’s health status during the period before and during shipping prep, not necessarily the exact moment of arrival or very recent post-arrival events. If infection happened after the sample was taken or during transit, arrival serology might not reveal it.