Which common canine disease is caused by a virus and leads to severe gastrointestinal issues?

The disease caused by a virus that leads to severe gastrointestinal issues in dogs is indeed Canine Parvovirus. This highly contagious virus primarily affects puppies and unvaccinated dogs, leading to symptoms such as severe vomiting, diarrhea (often bloody), lethargy, and loss of appetite. The virus attacks rapidly dividing cells in the intestinal lining, which results in significant damage to the gastrointestinal tract, dehydration, and can be life-threatening if not treated promptly.

Canine Distemper, while also a viral disease, affects multiple body systems including the respiratory and nervous systems, rather than being primarily gastrointestinal in nature. Canine Hepatitis, another viral disease, primarily affects the liver and causes symptoms related to liver dysfunction rather than gastrointestinal issues. Lyme Disease, on the other hand, is caused by a bacterium transmitted through ticks and typically leads to joint pain and fever rather than gastrointestinal distress. Therefore, Canine Parvovirus is the correct answer, as it specifically aligns with the question regarding severe gastrointestinal issues caused by a virus.