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The main issue with salt, is that it can cause hypernatremia (elevated sodium levels in the blood). In a dog this size, I would not expect you to see a problem if it was one bite of a necklace. The majority of toxicity cases are when owners give multiple teaspoons of straight salt trying to induce vomiting in a dog.
If you see vomiting within the next 10-15 minutes, that wouldn't be too unexpected. If you don't, then for sure it wasn't enough to cause issues. If you see vomiting, then I would watch her closely for 2-4 hours. If you notice any neurologic signs (incoordination, falling over, muscle tremors) then get to a vet for IV fluid therapy to normalize the sodium.
I don't think you'll end up having any issues given the amount and her size.