Canine Parvovirus Infection in Dogs
The canine parvovirus (CPV) infection is a highly contagious viral
illness that affects dogs. The virus manifests itself in two different
forms. The more common form is the intestinal form, which is
characterized by vomiting, diarrhea, weight loss, and lack of appetite
(anorexia). The less common form is the cardiac form, which attacks the
heart muscles of very young puppies, often leading to death. The
majority of cases are seen in puppies that are between six weeks and six
months old. The incidence of canine parvovirus infections has been
reduced radically by early vaccination in young puppies.
Symptoms and Types
The major symptoms associated with the intestinal form of a canine
parvovirus infection include severe, bloody diarrhea, lethargy, anorexia, fever, vomiting,
and severe weight loss. The intestinal form of CPV affects the body's
ability to absorb nutrients, and an affected animal will quickly become
dehydrated and weak from lack of protein and fluid absorption. The wet
tissue of the mouth and eyes may become noticeably red and the heart may
beat too rapidly. When your veterinarian palpates (examine by touch)
your dog’s abdominal area, your dog may respond with pain or discomfort.
Dogs that have contracted CPV may also have a low body temperature (hypothermia), rather than a fever.
Causes
Most cases of CPV infections are caused by a genetic alteration of
the original canine parvovirus: the canine parvovirus type 2b. There are
a variety of risk factors that can increase a dog’s susceptibility to
the disease, but mainly, the virus is transmitted either by direct
contact with an infected dog, or indirectly, by the fecal-oral route.
Heavy concentrations of the virus are found in an infected dog’s stool,
so when a healthy dog sniffs an infected dog’s stool, it will contract
the disease. The virus can also be brought into a dog's environment by
way of shoes that have come into contact with infected feces. There is
evidence that the virus can live in ground soil for up to a year. It is
resistant to most cleaning products, or even to weather changes. If you
suspect that you have come into contact with feces at all, you will need
to wash the affected area with household bleach, the only disinfectant
known to kill the virus.
Improper vaccination protocol and vaccination failure can also lead
to a CPV infection. Breeding kennels and dog shelters that hold a large
number of inadequately vaccinated puppies are particularly hazardous
places. For unknown reasons, certain dog breeds, such as Rottweilers, Doberman Pinschers, Pit Bulls, Labrador Retrievers, German Shepherds,
English Springer Spaniels, and Alaskan sled dogs, are particularly
vulnerable to the disease. Diseases or drug therapies that suppress the
normal response of the immune system may also increase the likelihood of
infection.
Diagnosis
CPV is diagnosed with a physical examination, biochemical tests,
urine analysis, abdominal radiographs, and abdominal ultrasounds. A
chemical blood profile and a complete blood cell count will also be
performed. Low white blood cell levels are indicative of CPV infection,
especially in association with bloody stools. Biochemical and urine
analysis may reveal elevated liver enzymes, lymphopenia, and electrolyte
imbalances. Abdominal radiograph imaging may show intestinal
obstruction, while an abdominal ultrasound may reveal enlarged lymph
nodes in the groin, or throughout the body, and fluid-filled intestinal
segments.
You will need to give a thorough history of your pet's health, recent
activities, and onset of symptoms. If you can gather a sample of your
dog's stool, or vomit, your veterinarian will be able to use these
samples for microscopic detection of the virus.
Treatment
Since the disease is a viral infection, there is no real cure for it.
Treatment is focused on curing the symptoms and preventing secondary
bacterial infections, preferably in a hospital environment. Intensive
therapy and system support are the key to recovery. Intravenous fluid
and nutrition therapy is crucial in maintaining a dog’s normal body
fluid after severe diarrhea and dehydration, and protein and electrolyte
levels will be monitored and regulated as necessary. Medications that
may be used in the treatment include drugs to curb vomiting
(antiemetics), H2 Blockers to reduce nausea, antibiotics, and
anthelmintics to fight parasites. The survival rate in dogs is about 70
percent, but death may sometimes result from severe dehydration,
a severe secondary bacterial infection, bacterial toxins in the blood,
or a severe intestinal hemorrhage. Prognosis is lower for puppies, since
they have a less developed immune system. It is common for a puppy that
is infected with CPV to suffer shock, and sudden death.
Living and Management
Even after your dog has recovered from a CPV infection, it will still
have a weakened immune system, and will be susceptible to other
illnesses. Talk to your veterinarian about ways by which you can boost
your dog's immune system, and otherwise protect your dog from situations
that may make it ill. A diet that is easily digested will be best for
your dog while it is recovering.
Your dog will also continue to be a contagion risk to other dogs for
at least two months after the initial recovery. You will need to isolate
your dog from other dogs for a period of time, and you may want to tell
neighbors who have dogs that they will need to have their own pets
tested. Wash all of the objects your dog uses (e.g., dishes, crate,
kennel, toys) with non-toxic cleaners. Recovery comes with long-term
immunity against the parvovirus, but it is no guarantee that your pet
will not be infected with the virus again.
Prevention
The best prevention you can take against CPV infection is to follow
the correct protocol for vaccination. Young puppies should be vaccinated
at six, nine, and twelve weeks, and should not be socialized with
outside dogs until at least two weeks after their last vaccinations.
High-risk breeds may require a longer initial vaccination period of up
to 22 weeks.