@Traci253
It is YOUR property.
If you clearly stated your NO PET POLICY in your House Rules, which the guest had to agree to in order to book your property, then the guest is in violation of your house rules, in which case you can call Airbnb and ask them to contact the guest, or you could send a polite message via the Airbnb message inbox asking why the dog is on your property. Be careful though, if you have undisclosed cameras, you would be in violation yourself.
You cannot charge a pet fee if you have a NO PET POLICY.
I've heard some hosts charge a pet fee only to discover that there may not be a limit on the number of pets. (Example: $50 pet fee....but not PER PET).
I believe you have the right to request the guest and his/her group (including the pet) vacate your property immediately. You would have to refund all remaining nights fees, but not the night(s) they stayed, nor the cleaning fee.
If the guest brought a service animal. That's an entirely different situation.
Do your research.
Be careful what you say/ask.
Good luck.