A number of common household plants -- including baby's breath, foxglove and poinsettia -- are highly toxic to dogs. How much of the plant your dog ingests and how big he is play a big part in what symptoms will develop, so keep that in mind. When in doubt, head to the vet.
The most common symptoms after eating a toxic plant are vomiting and nausea. Diarrhea, lethargy or weakness and nervousness are also common with some plants. Some plants might cause oral irritation, which could mean anything from red, swollen lips and tongue to burn-like marks.
If your dog has trouble breathing or seems extremely agitated or disoriented, head to the vet immediately. Some plants, including amaryllis and daffodil, can be fatal if ingested in large quantities.