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This is not normally a symptom of poisoning.
There are glands called bulbous glands at the base of the penis. These are normal and you will only see them at "happy times."
If the penis is distended, outside of the prepuce, I would worry about dryness and discomfort but it is not always a cause for emergency vet care. If you are comfortable with it, you can lubricate the penis and try to pull the sheath back over it.
Let me know if you still have questions about this. I fear that I have not answered your question completely.