The most likely sign you'll see here is GI upset- vomiting, esophageal irritation and potentially GI ulcers. Treatment is supportive with ant-acids and GI protectants. The one you can get over the counter is Pepcid. I would give 0.25 mg/lb orally twice daily for the next 3-5 days. If there are any burns in the mouth, it may help to give a little milk to offset the acidity. Do not try to get this dog to vomit as it would make the signs worse.
The good thing here is that it was diluted and signs should be mild, if any.
Hope this helps, let me know if you have any other questions.