A 6-year-old neutered male Labrador Retriever weighing 32 kg is presented with acute onset vomiting for the past 18 hours. The dog vomits repeatedly, including shortly after drinking water. The owner reports sudden anorexia and progressive lethargy. No diarrhea has been observed. On physical examination, the dog is dehydrated, tachycardic, and painful on abdominal palpation with increased abdominal tension. Mucous membranes are pale pink, and capillary refill time is mildly prolonged.