Which of the following are considered specified risk materials (SRM) in cattle of all ages?

• A. Vertebral column and dorsal root ganglia
• B. Spinal cord and trigeminal ganglia
• C. Tonsils and distal ileum
• D. Skull, eyes, and brain

Answer: (C)

SRMs are tissues with the highest risk of carrying the BSE agent and must be removed to protect human health. The set of tissues designated as SRMs varies with the animal’s age. For cattle of all ages, tonsils and the distal ileum are the SRMs because prions tend to localize in these lymphoid and gut-associated tissues early and consistently, regardless of how old the animal is. Other tissues—such as the spinal cord, dorsal root ganglia, trigeminal ganglia, skull, eyes, and brain—are SRMs only for cattle past certain ages, not for all ages. Since the question specifies cattle of all ages, the correct pair is tonsils and distal ileum.