Canine Coronavirus is a highly contagious virus that invades and replicates in the small intestine. The resulting symptoms are generally not too severe except if the dog is already infected with the Parvo virus. Together Corona and Parvo are synergistic producing exaggerated symptoms and possibly leading to death.
Corona is typically spread by fecal material. The virus can stay in the environment for months so transmission is fairly easy. Like many of the canine viruses multi-dog environments such as kennels, shelters and dog parks pose a higher risk. Also, puppies are more vulnerable than adult dogs.
The most prevalent symptom is watery diarrhea which tends to be more yellowish and foul smelling. Other symptoms include fever, loss of appetite, vomiting and depression.
There's no cure for Coronavirus. Treatment varies with the severity of the symptoms. With diarrhea you always want to be very cautious about dehydration. If the dog does get dehydrated, subcutaneous or IV fluids are needed to protect him from organ damage and going into shock.
Antibiotics are sometimes used to prevent opportunistic secondary infections. And some medications and dietary changes can be used to help with severe diarrhea and/or vomiting. The disease generally runs it's course within 10 days.
Since the virus can be anywhere dogs congregate and since puppies with less developed immune systems are more vulnerable, prevention for puppies includes avoiding these places and any contact with stray dogs.
There is a vaccination for Coronavirus. It's fairly effective but there are multiple strains of Corona so it's possible to be vaccinated and not be immune to all strains. You want to talk to your Vet to determine the prevalence of the virus in your area. As well you want to assess the risk relative to your individual situation.