Which test is preferred to screen for canine and feline infectious diseases with zoonotic potential in a symptomatic patient?

• A. Serology and PCR where indicated, plus culture when appropriate
• B. Only serology
• C. Only PCR
• D. Only culture

Answer: (A)

Infectious disease screening in a symptomatic dog or cat with potential to affect people relies on capturing both current infection and prior exposure, while also confirming the organism when possible. No single test can perfectly detect every zoonotic pathogen or distinguish active disease from past exposure. Serology reveals antibodies and can indicate prior exposure or immune response, but it may be negative early in infection and can be influenced by vaccination or cross-reactions. PCR looks for the pathogen’s genetic material, offering rapid, evidence of current infection, but its yield depends on sample quality, location, and pathogen load. Culture provides definitive proof of viable organisms and yields material for antimicrobial susceptibility testing, but many zoonotic agents are hard to grow, slow to culture, or require specialized biosafety facilities.

Using a combination approach—serology and PCR where indicated, plus culture when appropriate—maximizes diagnostic yield across different pathogens and stages of disease. This strategy improves the chance of identifying the infectious agent promptly, guides treatment, and helps protect humans by informing necessary precautions and public health actions.