Re HGE - our Jack Russell Annie went thru this about four
years ago - very frightening. No sounds from her during the night, but when we woke up our bedroom looked like a slaughter house - projectile bloody vomiting and bloody diarrhea and she was like a limp little rag. We wrapped her in a big towel and had her at our vet within 15 minutes where they immediately took over - had it been much longer she would not have survived. Our vet said there is really no explanation for this. Two days at the vets on IVs, then special diet at home for two weeks - then back to her old tricks. But I keep a close watch.