This article is from the Canine Medical Information FAQ, by Cindy Tittle Moore with numerous contributions by others.
(summarized From Carlson & Giffin)
This disease should NOT be confused with human hepatitis. This is a
highly contagious disease transmissible only to dogs. It affects the
liver, kidneys and lining of the blood vessels. It can sometimes be
hard to distinguish from distemper as there are a variety of signs and
symptoms that range from mild to fatal. Exposed dogs rapidly become
contagious and remain contagious throughout convalescence.
Fatal form: the dog becomes ill, develops bloody diarrhea, collapses
and dies. Puppies may die without symptoms.
Acute form: High fever, bloody diarrhea, possibly bloody vomit.
Refusal to eat and painful movements. The dog can become
Mild form: Lethargy, possible loss of appetite.