Friend, vomiting, and lethargy can be caused by many different medical conditions. The fact that she ate 1/2 of a powdered donut prior to this happening I would want to rule out pancreatitis. The shaking and abdominal muscles contracting are likely signs of pain which further supports pancreatitis. Could this be related to something else? Yes. But, given that pancreatitis is a very serious medical condition I would strongly recommend having her checked tonight by ER veterinarian to rule out pancreatitis, I am sorry, but, it is best to err on the side of caution. If you do not have access to ER veterinarian this is what you can to until she is seen by your family veterinarian in the morning:
1- Do not give things like Pepto Bismol or Imodium. Start her on Pepcid AC (famotidine) 10mg 1/2 tablet every 12 hours. You can buy Pepcid AC over the counter in any pharmacy. Do Not give over the counter pain medication, it can make things worse.
2- No food or water for 8-12 hours. Need to give her gastrointestinal tract time to rest.
3- After 8-12 hours offer a small amount of water. Wait half hour, if no vomiting, she can have a small amount of water. Keep her off food for 20-24 hours. Then, offer a small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day. Keep on this diet for 1-2 weeks then wean into regular diet.
4- Follow up with your family veterinarian for a hands on examination.
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