Final answer:
The sign indicating a risk for developing colic with opioid treatment, such as with morphine, is the presence of gastrointestinal side effects, including nausea and constipation, which suggest decreased bowel movements and motility issues.
Step-by-step explanation:
The sign that indicates a patient is at risk for developing colic as a treatment with morphine or other opioids is the onset of gastrointestinal side effects such as nausea, constipation, and decreased bowel movements. Opioids like morphine, oxycodone, and codeine can lead to gastrointestinal motility issues, which is a precursor to the development of colic, a severe abdominal pain associated with bowel dysfunction. The slowing of gastrointestinal transit is a known side effect of opioid medication and can indicate a higher risk of developing more serious conditions such as colic.