The Dreaded Parvovirus

If you follow celebrity news, you’ll know that Oprah recently took in two Cocker Spaniel Puppies from Paws Chicago.  Soon after she got them, little Ivan passed away from Parvovirus.  Sadie, who also had the disease, recovered.  Parvo is one of the most common viral illnesses in dogs, and is particularly common in puppies.

So, what is this disease and how can you protect your dog from this often fatal illness?

Parvo is covered in detail in an article in our doggies den, but here is a summary.

What causes parvo?

Although we know that parvo is caused by a virus, no one is quite sure exactly how the infection happens.  The virus attacks cells that grow and divide quickly, meaning that puppies are especially at risk.  Typically, the virus attacks the cells of the digestive tract first, causing bloody diarrhea.  Next, the infection moves to the bone marrow, destroying the production of white blood cells which the puppy would normally use to fight infections.  Finally, the virus can also infect the heart muscle, leading very quickly to death from congestive heart failure.

Adult dogs can be infected with parvovirus without showing any symptoms at all.  Droppings from an infected disease can transmit the virus into the surrounding soil, which may remain contaminated for as long as a year.  If a puppy swallows some of the infected soil, he or she will become very sick within a week to ten days.

Parvo is often contracted when puppies are on walks around the neighborhood or visiting a dog park.  But even if you keep your dog in your own yard, there is a risk of contamination.  If a shoe or a tire or a bird or a squirrel tracks through contaminated soil, the virus can be brought right to your puppy’s own habitat.  It is thought that birds who step in the virus then subsequently take a bath in your puppy’s outdoor water dish can be a significant route of disease transmission.

In spite of the very real risk to puppies, parvo is not a virus that can be transmitted to other species of animals or to humans.  Your cat and your children are at no risk if you have an parvo-infected puppy in your home.

Symptoms

When a puppy first becomes sick with parvo, the primary symptom will be bloody diarrhea.  The stool may be more foul-smelling than usual and may have a distinctive yellow color.  The dog may also develop vomiting and a high fever.  The combination of these three factors can quickly lead to dehydration, a medical emergency.   Untreated, the dog will go into shock, soon followed by death.

Even if a dog recovers from the intestinal form of the disease, there is no guarantee that the virus will not subsequently become active at a future date, often attacking the heart muscle months or years after the original illness.  The virus that causes parvo is extremely hardy and can live on inside or outside of a host for extended periods of time.

What breeds are prone to get Parvo?

Although the exact reasons are unknown, black and tan dogs seem to suffer a higher rate of parvo infection than other breeds.  This includes Rottweilers, Doberman Pinschers, Manchester Terriers, and Dachshunds.  However, any dog can develop the disease and must be protected.

What should I do if my puppy has diarrhea?

Although many puppies get diarrhea when they don’t have parvo, the effects of this particular virus are so devastating that it pays to have your dog checked by a vet even if you don’t think it really is parvo.  Parvo can be very quickly fatal, and it’s worth the cost of a vet trip to make sure the diarrhea has a more benign cause rather than simply writing it off as worms or an upset stomach.

Your vet will do a test of the dog’s feces called an enzyme-linked immunosorbent assay antigen (ELISA) test, also known as a CITE test.  In addition, he or she may draw blood for a blood count and chemistry panel to determine how far the disease has progressed.

Fast, effective treatment is key to keeping your puppy alive after he or she is infected with the parvovirus.  With intense treatment, about 80% of puppies will survive, although they will likely always be sickly.  Without treatment, about 80% of parvo victims die.

The most important type of treatment is strictly supportive to keep the dog from becoming dehydrated after losing so much fluid to vomiting and diarrhea.  Usually, fluids and electrolytes are replaced through an IV, but in less severe cases, oral fluids may be used.  In more severe cases, blood transfusions may be required to build up the body’s defenses until the bone marrow recovers enough to begin producing sufficient white blood cells.

Depending on your dog’s symptoms and the severity of the disease, the dog may also be given medicine to reduce vomiting, antibiotics to control any secondary bacterial infections that might occur, and steroids to guard against shock.  Sometimes, the dog must be fed through an IV, and at the very least, food will be restricted to a very bland diet until the digestive tract heals.

OK, I’ve treated my puppy.  Now what?

After you have treated your puppy for parvovirus, the next most important task you have is to clean the environment to rid your house and yard of the virus and prevent the spread to your other dogs.  You also don’t want the puppy to be re-infected.  The best cleaning agent to use against parvovirus is chlorine bleach diluted to ½ cup per gallon of water.  Wipe down any surfaces that may have become contaminated.  Wash all bedding where the dogs may sleep using chlorine bleach.  Clean all the dogs’ dishes with the same bleach solution.  Keep the infected dog isolated from your other dogs for at least a month after he or she recovers, and clean up all stool immediately.

How do I prevent my puppy from getting parvo?

Vaccinate.  Vaccinate.  Vaccinate.  The only sure way to keep your dog from getting this deadly disease is to provide proper and timely vaccinations.  However, in a deadly paradox, one of the problems with vaccinating puppies is that the antibody protection given by the mama dog’s milk can actually interfere with the vaccination.

Parvo vaccine is given as a live virus.  A nursing puppy will be getting antibodies from his or her mother’s milk, including antibodies to fight parvo, so the live virus in the vaccine may be killed before it has a chance to stimulate the puppy’s own immune system to fight the disease.

Depending on the strength of the mother’s antibodies and the size of the litter, the puppy will be protected for a variable length of time.  If immunizations don’t start soon enough, the puppy will be susceptible to the disease.  If they start too soon, the mother’s antibodies will negate the effect of the vaccine.

Some vets will begin vaccinating a puppy at six weeks, just as it begins to wean, then repeat the vaccination every three or four weeks until the puppy reaches 20 weeks old. In one study cited by Drs. Foster and Smith about ¼ of all puppies are able to respond appropriately to the parvo vaccine by six weeks of age, while about 95% can respond by 19 weeks, so vaccinating several times within that window seems to be the best course of action.  After the age of 20 weeks, most dogs are immunized with a booster annually.