Why were the control dogs euthanized?

• A. Traumatic injuries
• B. Old age
• C. Chronic illness
• D. Behavioral concerns

Answer: (A)

In animal research, decisions to euthanize are driven by welfare and humane endpoints. If a control dog sustains traumatic injuries that cause significant pain, have a poor prognosis for recovery, or risks of ongoing suffering, euthanasia is performed to prevent further distress. This is the most appropriate and ethical action, even in a control group, because it prioritizes the animal’s welfare over continued participation in the study.

Old age or chronic illness could be reasons for euthanasia in other contexts, but they describe gradual decline rather than acute, distressing injury. Behavioral concerns might lead to removal from a study if they compromise welfare or data quality, but the explicit indication of traumatic injuries points to a welfare-driven humane endpoint as the rationale.