Final answer:
The recommended treatment for mild dehydration in a 3-year-old with diarrhea is oral rehydration therapy using an oral rehydration solution. Antibiotics are not necessary in this case.
Step-by-step explanation:
The recommended treatment for a 3-year-old with mild dehydration due to diarrhea is oral rehydration therapy. This involves giving the child a special solution called oral rehydration solution, which contains water, salts, and sugar. The solution helps replace the fluids and electrolytes lost through diarrhea and prevents further dehydration.
Intravenous fluids may be necessary in severe cases of dehydration, but in this mild case, oral rehydration therapy should be sufficient. Antibiotics are not usually prescribed for gastroenteritis because it is often caused by viruses, which antibiotics cannot treat effectively.