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Is your dog showing any signs at this point?
How long ago was the ingestion?
It doesn't sound like you're seeing the typical toxicity signs. Usually we'll see vomiting and neurologic signs. The toxin in morning glory plants is like LSD. They have hallucinations, muscle tremors and potentially seizures. They typically occur within 6-8 hours of the ingestion.
I think the signs today are from the plant material moving through the gut. That can lead to some discomfort and decreased appetite. It wouldn't hurt to get him seen and get some fluids in him. They could do IV or sub Q (under the skin) to help rehydrate him and get the gut moving better. Otherwise, you may be able to just wait it out a bit longer and things should resolve over the next 12-24 hours.
I hope this helps, let me know if you have any other questions.