From the Merck Vet Manual:

http://www.merckvetmanual.com/mvm/in...m/bc/23311.htm

Hemorrhagic gastroenteritis (HGE) is characterized by an acute onset of bloody diarrhea in formerly healthy dogs.
Young, toy, and miniature breeds of dogs appear predisposed. Mortality is high in untreated dogs.

Etiology and Pathophysiology:
The etiology is unknown. An abnormal response to bacteria, bacterial endotoxins, or diet may be involved, but evidence is lacking. Clostridium perfringens has been cultured from some dogs with HGE, although its significance is unknown. Escherichia coli has also been identified from some dogs with the disease, but no toxigenic strains have been isolated. There is no sex predilection, and dogs of any age may be affected. King Charles Spaniels, Shetland Sheepdogs, Pekingese, Yorkshire Terriers, Poodles, and Schnauzers may be more frequently affected than other breeds. Hyperactivity and stress are possible contributing factors. Although no definitive cause has been found, a marked increase in vascular and mucosal permeability is likely. RBC, plasma, and fluid leak into the bowel lumen. Inflammation and necrosis are rarely seen. The increase in bowel permeability may represent a type I hypersensitivity reaction. Inciting factors may include food allergens, bacterial products, or intestinal parasites. Splenic contraction and the loss of fluid into the bowel contributes to the increased PCV and the maintenance of a low or normal serum total protein.

Clinical Findings:
The disease is often seen in dogs 2-4 yr old and is characterized by an acute onset of vomiting and bloody diarrhea, anorexia, and depression. Dogs are not clinically dehydrated, but unless fluid support is initiated, hypovolemic shock may develop. The disease is not contagious and may be seen without obvious changes in diet, environment, or daily routine; the history is unremarkable.

Diagnosis:
Diagnosis is based on the clinical sign of acute, bloody diarrhea accompanied by an increased PCV, which is often >60%.
Findings on physical examination and biochemical profile tend to be normal.
Other causes of GI bleeding that should be considered include parvovirus, coronavirus,
Campylobacter spp , Salmonella spp , Clostridium spp , Escherichia coli , and leptospirosis,
as well as whipworms, hookworms, coccidiosis, and giardiasis.
Coagulopathies (including warfarin toxicity and thrombocytopenia), GI neoplasia, ulceration, colitis,
and hypoadrenocorticism are other potential causes of GI bleeding.

Treatment:
Most dogs respond to supportive treatment, including fluid therapy (eg, lactated Ringer’s) and antibiotics (eg, ampicillin at 20 mg/kg, IV, tid and gentamicin at 2.2 mg/kg, SC, tid). Potassium chloride should be added to the IV fluids. Less severely affected dogs may be treated with amoxicillin, trimethoprim-sulfa, fluoroquinolone, or cephalosporin antibiotics. Food and water should be withheld for 2-3 days. When vomiting has ceased, food can be gradually reintroduced. Because of the possibility that food sensitivity may be an inciting factor, the protein source chosen should be one not previously fed to the dog, eg, cottage cheese, lamb, or tofu, mixed with rice. This diet is fed for 1-2 wk, after which the dog’s regular diet can be gradually reintroduced.

Serious complications are uncommon but may include disseminated intravascular coagulation.
Most dogs recover.
Fewer than 10% of treated dogs die, and 10-15% have repeated occurrences.
---------------------------------------------------------------------

With the early intervention treatment Tucker is getting,
his prognosis should be excellent. Here's a Prayer that the 'fix' is
quick and complete!

Hurry Home, Tucker!!

{{{Hugs}}} to Mom!

/s/ Phred