Think happy thoughts for Dogger

Hemorrhagic gastroenteritis (HGE) usually causes a very sudden onset of vomiting, bloody diarrhea, dehydration and depression. Dogs affected by this condition get very sick, very fast.

To the best of my knowledge, the exact cause of this disease is unknown. It appears that Clostridium species bacteria may be part of the cause. The disease is more frequent in small breed dogs but can occur in any dog. I am not sure what the general impression is among veterinarians, but dogs that have this problem seem to have a high risk of getting it again in our practice.

Most dogs respond very well to treatment with fluids to restore hydration. In some cases it is necessary to give plasma to correct loss of protein and antibiotics to combat the suspected Clostridium infection. In a few dogs, it is necessary to give fast acting cortisones to counter shock, which is a problem due to the very rapid onset of dehydration in dogs with HGE.

It is generally necessary to totally restrict oral food and water for one or two days when treating this problem. This makes hospitalization necessary for several days for most dogs with HGE.

HGE

More on HGE ( it sounds less awful that way)

From Dog Health

From The Merck Vet Manual