Coronavirus
December, 1996
A few months ago, my article dealt with canine parvovirus and
the serious intestinal disease it can cause. This month, I’ll
describe canine coronavirus, which is probably the second most
important cause of virus-infected intestinal disease (viral
enteritis) in dogs.
It was first identified in 1971 and, like parvovirus, has
world-wide distribution. Also like parvovirus, the primary mode
of transni ission involves ingestion after environmental
contamination with the stool of an infected dog. Due to the
prevalence of antibodies against the virus, it is believed that
most adult dogs have been exposed to the virus, even if they have
never shown signs of the disease. In a kennel situation, the
virus is highly contagious and spreads rapidly from dog to dog.
In contrast to parvovirus, coronavirus is easily killed by most
chemical d is infectants.
The incubation period of the disease is probably as short as I -
3 days. Unlike parvovirus, this virus only infects the intestinal
tract and rarely spreads to any other body systems. The intensity
of the signs of disease is highly variable but usually mild or
non-existent. As with parvovirus, possible signs includes
diarrhea. vomiting, poor appetite, lethargy and fever. The
diarrhea is usually not bloody but often has an orange-tinted and
unusually fetid odor. Most infected dogs improve after a few days
of clinical symptoms without aggressive treatment, but very young
puppies are most likely to show serious disease. Unlike
parvovirus, recovered dogs have shortlived immunity, but usually
shed the virus in their stool for months. Dual infection with
parvovirus and coronavirus at the same time have been shown to be
more severe than either virus alone.
As with any viral enteritis, treatment is purely supportive.
Fluid therapy battles the dehydration caused by vomiting and
diarrhea. In animals that are able to hold down oral liquids
without vomiting, it
may be possible to maintain hydration with oral electrolyte
solutions, such as Pedialyte or Gatorade. Subcutaneous or
intravenous fluid administration may be required. Food should be
withheld for one or two days. If drinking induces vomiting, water
should also be withheld. When the dog’s stomach is ready, a
small amount of a bland diet should be offered. If this is
tolerated, small amounts can be offered frequently, and the
normal diet gradually re-introduced over a few days. Antibiotics
can be used if signs of intestinal damage are severe. Injectable
medications to control vomiting may be used. Oral drugs such as
Pepto-Bismol or KaoPectate have minimal effects.
Because of similarities between all causes of viral enteritis,
definitive diagnosis of canine coronavirus requires laboratory
confirmation. Relying on the detection of antibodies in the
blood-
stream can be deceiving, due to the prevalence of antibodies in
dogs without disease. However, diagnosis can be made by
demonstrating a four-fold increase in antibody level between
samples drawn during the illness and again two to six weeks
later. Diagnosis can also be achieved at those laboratories that
can identify the virus in stool. However, because of the virus’s
natural instability, false negatives occur when there are
shipping and processing delays. Relying on post mortem exam for
diagnosis can also be disappointing because the intestinal
lesions caused by coronavirus are fairly mild, not very specific
and are obliterated a short time after death.
Vaccines against canine coronavirus exist, but their
effectiveness is questionable. There does not appear to be a good
correlation between the level of antibodies in the bloodstream
and resistance to coronavirus infection. In addition, any
protection that does occur after vaccination may be as
short-lived as that which occurs after natural infection.