URGENT-Veterinarian?

What are the symptoms of a dog that has licked his paws after getting city rock salt caught in his pads? He has been drooling for hours.What should we be looking for? We called his vet, and she said if we had concerns to call her back. Didn't think there would be a problem if he didn't ingest it, but we don't know for sure, if he did or didn't. Is he in danger? Thank you so much. Stormy