Okay, back from the vet. The dogs were both unusually hyper by the time we got there - the staff all know them and said "they aren't usually like that". Their temps and hydration are good, but they both had tender tummy regions, glassy eyes and were panting like they were in pain (I know that one from Violet with her chronic hip pain). The vet said (as you already alluded, Pac) that she can only guess it was the salt because I can't come up with anything else they could have got in a 48 hour period.
We have to watch them carefully and they are both on some stomach medicine for three days. If it gets worse or no better, I have to take them back for more tests.
I am exhausted from being up with Violet most of the night and then dealing with Joie and then rushing to the vet. After TB leaves for work I am hoping the three of us can have a good nap.
Thanks everyone for allowing me to go crazy here - they may be animals, but they are my only "kids".