Ask a Vet and Get Your Veterinary Questions Answered.
Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern about your dog but happy to reassure you that he/she should be fine.
While onions can be toxic to dogs, it would take ingestion of about 1 pound for a 15 pound dog to develop serious symptoms.
Clearly, the onion soup mix didn't contain even close to that amount.
It's possible that diarrhea might develop in 12 -24 hours although a bland diet of boiled chicken and rice should resolve the issue within a day or so.
He/she should be fine; no action is necessary on your part.
I hope this helps to provide peace of mind. Deb
I'm just following up on your dog. I assume he's doing fine but wanted to double check. Deb