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An
Overview of Canine Coronavirus
The canine
coronavirus (CCV), though significantly less severe than either distemper
or parvovirus, is nevertheless recognized as an important pathogen
of dogs that is capable of producing a debilitating sickness. It is
thought that CCV sometimes strikes in conjunction with canine parvovirus,
causing an illness more deadly than that triggered by either virus alone.
Though
there is evidence that it existed earlier, CCV was first described in
1971 by a German scientist. In the three decades since the virus has
been documented in the United States, Thailand, Australia, and throughout
Europe. Despite the fact that it is not as vicious a killer as either
parvovirus or distemper, it is still recommended that your pet’s
vaccination schedule include shots for CCV.
 Why
and how might my dog become infected?
It is
not known precisely how long CCV particles can survive outside the animal,
but given data from studies of exposure in healthy dogs, it can be assumed
that the virus is extremely common in the environment. Despite this,
not every dog will become infected. This is because several factors
influence the effectiveness of the virus. Host vitality (overall health
of the dog, immune experience, vaccination status), virulence of the
virus (the number of viral particles in a given area), and other environmental
factors (stress, dry weather, cold weather) all interact and ultimately
determine whether or not an individual dog will become infected. The
most important factors seem to be the immune level of the individual
dog and the number of viral particles the dog is exposed to. If each
factor is ‘just right’ however, a dog will become infected.
When this occurs, a specific sequence of events is initiated as the
virus attacks the body.
The route
of transmission for this virus is fecal-oral, meaning that infected
dogs shed viral particles in their feces, and healthy dogs contract
the disease by licking, eating or even drinking substances that have
been contaminated. CCV capsids are acid resistant, and thus pass unharmed
through the dog’s stomach on their way to the target organ, the
small intestine.
The incubation
period is short, and vomiting and diarrhea generally appear
1 to 3 days after initial exposure. The symptoms are a result of the
virus infecting the cells covering the upper two-thirds of the villi
lining the small intestine. The infection is confined to the intestines
and damage is limited further to mature cells – the intestine’s
ability to produce new, healthy cells remains uncompromised. Nevertheless,
the infected villi become damaged and blunted to such an extent that
the small intestine can no longer effectively absorb nutrients.
As a testament
to the relative mildness of CCV, healing of intestinal inflammation
is generally complete within 1 week. Despite its mildness when contracted
alone, it is important to note that, if contracted in conjunction with
CPV, the resulting illness is far more severe than either CCV or CPV
alone.
How
will my vet reach a diagnosis of CCV?
Like so
many viral infections, the symptoms of CCV are nonspecific and often
ambiguous. Bouts of vomiting, diarrhea, dehydration, mild depression,
and loss of appetite are all signs that CCV may be present. A low grade
fever has sometimes been observed with CCV infections, but it is easy
to overlook such a symptom.
Diagnosis
is generally a process of elimination, and there is no definitive test
for CCV. Perhaps the most helpful tool when seeking a diagnosis of CCV
is electron microscopy. A sample is examined under the electron
microscope for signs of the characteristic viral particles.
There is some margin for error with this procedure however as CCV particles
are not particularly stable and may disintegrate before the lab has
a chance to examine the sample.
A veterinarian
will therefore take all lab test, symptoms, and vaccination history
into account when searching for a diagnosis.
What are the treatment options for dogs with CCV?
There
is no cure for CCV. It is not however usually a fatal affliction, and
supportive treatment is usually sufficient to assure a complete recovery.
A sick dog should be placed in a warm, comfortable environment and monitored
to be sure that dehydration does not become too severe. In cases involving
particularly harsh bouts of vomiting or diarrhea, intravenous fluids
may be given, but this is rare with CCV.
How do I vaccinate my pet against CCV?
Vaccines
are complex substances and raise many questions. For information about
vaccines in general, please go to An
Introduction to the World of Vaccines.
Not every
veterinary hospital recommends vaccination against CCV, but many include
the vaccine as part of the combined distemper/parvo shot. These inoculations
are given every 3-4 weeks from the time a puppy is 6 weeks old until
he is at least 16 weeks of age.
How else can I help prevent the disease?
The keys
to preventing CCV infection are vaccinations and avoidance. Unvaccinated
puppies and adult dogs should be kept away from public places where
many dogs are likely to be present. Crowded, unsanitary conditions should
be shunned, and owners should seek to alleviate stress in their pets.
The virus
is not as rugged as the nearly indestructible parvovirus, and can be
wiped out by cleaning with a 3% bleach solution.
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