In nonhuman primates, tuberculin testing involves intradermal injection in which location?

• A. The inside of the front limb
• B. The back of the ear
• C. The back of the neck
• D. The upper eyelid

Answer: (D)

Tuberculin testing in nonhuman primates relies on placing the intradermal injection where a clear, measurable skin reaction can develop and be easily observed. The upper eyelid is used because the eyelid skin is thin and highly visible, so induration or edema from the tuberculin reaction can be detected reliably within a standard reading period. This site also minimizes interference from fur and movement, and it allows a consistent, straightforward assessment. Other areas—like the inside of the forelimb, the back of the ear, or the neck—have thicker skin, more movement, or less visible reactions, making readings harder and potentially less accurate.