Infectious Canine Hepatitis
Puppies at four weeks, by davidsmalley
The H represents infectious canine hepatitis, a viral disease that targets the liver, as well as the kidneys, eyes, and the vascular endothelium, the cells lining the inner surfaces of blood vessels.
There is a range of how the disease affects animals. The most severe form can very rapidly affect young puppies, but dogs of all ages can be affected.
Signs of illness can include a high fever, vomiting and diarrhea, abdominal pain, a reddening of the mucous membranes and hemorrhaging from the nose, gums, GI tract, and under the skin.