Coronavirus in dogs
Canine Coronavirus ties with Canine Parvovirus as the leading viral causes of diarrhea in puppies. Clinically, the 2 infections can be indistinguishable. But they are quite different in their final effect - Canine Coronavirus rarely kills the puppy while Canine Parvovirus often does. The virus appeared suddenly in Europe in 1971, and some scientists speculate that Canine Coronavirus may have mutated from another Coronavirus that causes a similar disease in pigs.
Canine Coronavirus is an RNA-type virus and a member of the Group I Coronaviruses. When the virus is viewed under an electron microscope the particles have a halo-like crown of projections or corona. Coronavirus is surrounded by a fatty protective coating which makes it rather easy to kill with detergent and solvents that dissolve fats. This is in contrast to Parvovirus, which is very tough and hard to kill. Coronavirus is spread from dog to dog through infected feces.
Canine Coronavirus is widespread in the dog population worldwide. It invades the rapidly growing cells of the intestinal lining causing nausea, lack of appetite, vomiting, and diarrhea. It is primarily a disease of puppies. Coronavirus is shed in the feces of infected dogs for months after initial ingestion. It takes 1 - 3 days from the time the puppy is exposed to an infected dog's stool for it to become visibly sick.
Most dogs probably become infected with Coronavirus and recover without getting ill or after a sickness too mild for owners to notice. We know this because most adult dogs have antibody to this disease which indicates that they were, at one time, exposed to the virus.
Different Virus Strains
There are slight differences between Coronavirus strains isolated from puppies with diarrhea. So puppies and dogs immune to a particular strain of Coronavirus may not be immune other strains of the virus.
Canine Respiratory Coronavirus
We now know that a 2nd type of dog Coronavirus exists. This strain, known as Group II, affects the dog's respiratory tract rather than its intestine. It causes coughing, sneezing, and a nasal discharge. It is one of the organisms involved in what we call kennel cough or CIRD. When it is a problem, it is usually working in combination with other disease organisms. It is seen most often when large numbers of dogs are housed together such as in boarding kennel, animal shelters, dog shows, and dog race tracks.
Canine Coronavirus FAQ
Q: What is canine respiratory coronavirus?
A: Canine respiratory coronavirus (CRCoV) is a group 2 coronavirus. It is genetically related to the bovine coronavirus (which can cause respiratory infections in cattle) and the human coronavirus that causes the "common cold" in people. CRCoV is NOT related to the group 1 enteric coronavirus that can cause diarrhea in dogs.
Q: Where does CRCoV occur?
A: CRCCoV was initially discovered in dogs with acute respiratory infection in England in 2003. This virus commonly infects dogs in the United Kingdom, Ireland, Greece, Italy, and Japan.Recent studies have shown that CRCoV is also present in the U.S. and Canada, where about 50% of tested dogs had antibodies to the virus, indicating past infection.
Q: How is CRCoV transmitted?
A: As with other respiratory pathogens, CRCoV is highly contagious and is spread by direct dog-to-dog contact, aerosols of respiratory secretions, and contact with contaminated environments or people. The most efficient transmission occurs by direct contact with infected dogs and by aerosols generated by coughing and sneezing. Virus can also contaminate kennel surfaces, food and water bowls, collars and leashes, and the hands and clothing of people who handle infected dogs.
Q:What are the clinical signs of CRCoV infection?
A: Most dogs have a mild disease consisting of cough, sneezing, and nasal discharge. Some dogs have a subclinical infection with no clinical signs, yet they shed virus that can infect other dogs. A small minority of dogs infected with CRCoV have progressed to pneumonia, particularly if co-infected with other respiratory pathogens. The incubation time from CRCoV exposure to clinical disease is unknown, but may be a few days. The number of days that virus is shed is also unknown. The clinical signs usually resolve after 1-2 weeks, depending on whether co-infection with other pathogens is involved.
Q: What is the treatment for CRCoV infection?
A: There is no specific anti-viral therapy for CRCoV infection. Treatment consists of supportive therapy based on clinical signs. Antibiotics may be needed if there are signs of secondary bacterial infection. Since CRCoV is highly contagious, isolation of infected dogs is necessary to minimize spread of infection. The quarantine time for infected dogs is unknown since the time period for virus shedding has not been defined. A conservative estimate based on other respiratory viruses is 3 weeks. However, co-infection with other pathogens such as distemper virus or Bordetella bronchiseptica will extend the quarantine time since these agents can be shed for months.
Q: Is there a vaccine for CRCoV?
A: At this time, there is no vaccine to prevent CRCoV infection or reduce the clinical disease. CRCoV is not related to the canine enteric coronavirus; therefore, vaccines for canine enteric coronavirus are NOT effective. Studies have shown that CRCoV infection generates antibodies that reduce the risk for re-infection or at least reduce the clinical disease if infection occurs. The duration of infection-induced immunity is unknown.
Q: How is CRCoV infection managed?
A: Important management strategies for reducing spread of CRCoV infection include isolation of sick and exposed dogs, biosecurity measures (such as changing of clothes and hand washing after handling affected dogs), and effective sanitation. The length of time that CRCoV persists in the environment is unknown, but may be at least several hours. Most viruses that cause CIRD are inactivated by routinely used disinfectants (except for adenovirus). Disinfected surfaces should be thoroughly dried because moisture promotes virus survival.
Q: How is CRCoV infection prevented?
A: Even though there is no vaccine for CRCoV, dogs in boarding/training kennels, shelters, and dog shows should be vaccinated against other respiratory pathogens for which vaccines are available, including parainfluenza virus, adenovirus, distemper virus, and Bordetella bronchiseptica. This will reduce the risk for co-infection with these pathogens. Clinical disease in dogs infected with CRCoV can be more severe if co-infections occur.