Why is my nursing dog shaking? Is it eclampsia or something else?

Hi there and thank you for using Petco Pet Education Center, formerly Petcoach! During nursing, Jewels' body is using up a lot of calcium storage to help create milk for the nursing puppies. Consequently, this usage of calcium in her body can cause her levels to drop rapidly and cause her to go into a hypocalcemic state known as eclampsia. This can rapidly progress if not addressed right away to full on convulsions. I would recommend taking her to the veterinarian and having her calcium levels tested to see if she is in need of supplementation or not. There may be a different cause but with her feeding the puppies, this is high up on my list. She could also be cold or anxious. Regardless of the proposed cause, it would be best to have a veterinarian take a look at her sooner rather than later. I hope this helps! Please let me know if you have any other questions or concerns and I would be more than happy to help you further.