Final answer:
The common side effect of narcotics in dogs is respiratory depression. It is crucial to monitor for this life-threatening condition when dogs are given narcotic medications for pain relief.
Step-by-step explanation:
One common side effect of narcotics in dogs is D. respiratory depression. Narcotics, particularly opioids, are substances that can be used for pain relief but may lead to various side effects. While they do provide analgesia and pain control, higher doses of narcotics can cause significant respiratory depression, characterized by a reduction in the urge to breathe and a decrease in the frequency and depth of respiration. This side effect is particularly important to monitor because it can be life-threatening. Other effects of narcotic use in dogs can include sedation, anxiolysis, and in some cases, low blood pressure or decreased heart rate.