Ashland Area Vet Clinic


PARVOVIRUS IN DOGS

PARVOVIRUS IN DOGS

THE DISEASE                                                            

INTESTINAL FORM:  Sadly, we see entirely too many cases of generally preventable parvovirus in puppies and occasionally, in unvaccinated adults.  The deadly disease usually begins with lethargy and loss of appetite and progresses to vomiting, diarrhea, severe depression, dehydration, and finally death. As the diarrhea worsens, it becomes bloody and has an extremely foul odor.  The severity of parvo disease depends upon body weight, age, environmental stresses, parasitism, other diseases, and the amount of immunity (antibodies) received from the mom.  Without veterinary intervention, most afflicted puppies will become dehydrated, lose significant amounts of body fluids, go into shock, and pass away miserably.  Unfortunately, even with treatment, a small percentage of these puppies will also die. 

     The longer the beginning of treatment is delayed, the more likely we will see an unsuccessful outcome.  Several mutations of parvovirus have occurred.  More recent mutations are more likely to cause disease and are more difficult to treat.

CARDIAC FORM:   In this rare form of parvovirus, severe inflammation kills heart muscle cells, resulting in the deaths of puppies generally younger than 8 weeks of age.  These pups exhibit extreme difficulty breathing as the heart fails.

ASYMPTOMATIC:  Inadequately vaccinated adult dogs occasionally will contract parvovirus and exhibit few or no symptoms while still shedding the disease in their stool.

 

SOURCES AND SUSCEPTIBLITY

     Unvaccinated (or recently recovered) dogs, wolves, coyotes, foxes, and other canids, are reservoirs (sources) of parvovirus.  Infection is by ingestion of the virus from feces or vomit of infected animals.  We see the disease most commonly where there are large numbers of unvaccinated dogs.  Shelters are especially at risk.  Though staff may vaccinate dogs upon arrival, new shelter residents may already be infected or may have poor immune responses because of stress, previous starvation, heavy parasitism, or other neglect.

     There seems to be a lowered resistance in some breeds, especially the black/tan varieties.  Doberman pinschers, rottweilers, pit bulls, German Shepherds, and dachshunds seem particularly prone to parvovirus.  Most victims are puppies 6 weeks to 6 months of age.

 

 

DIAGNOSIS

     Extreme lethargy, vomiting, and diarrhea in a puppy make us consider parvovirus.  Similar symptoms may accompany other conditions such as severe parasite burden, other viral or bacterial infections, hemorrhagic gastroenteritis, foreign body impaction, or physical restriction of the bowel (intussusception or tangling).  The in-house fecal “snap test” for parvo is not perfect.  It may show us a false negative because of the short time of viral shedding in the stool.  It can also indicate a false positive if the puppy has been vaccinated in the last 5 to 15 days.  Blood count, x-rays, and testing for intestinal parasites may also be helpful for a diagnosis. 

 

TIME LINE: 

·         Puppy has oral exposure to vomit or feces of another canine with parvo.  (This highly contagious virus can survive easily up to 7 months in the environment, longer if frozen in winter months.)

·         Virus is in the blood stream by 3 to 5 days.  (Usually, the puppy still seems normal at this point.)

·         The puppy begins to shed highly contagious virus in stool 4 to 5 days after exposure.

·         The puppy has early symptoms 5 to 14 days after exposure. (Rarely, early symptoms can be seen as early as 3 days after exposure.)

·         Fecal shedding of virus is much less by 14 days after exposure, generally ending completely by 3 weeks.  (Fecal material left on coat from highly viremic early diarrhea is still very contagious.)

 

TREATMENT

·         FLUID REPLACEMENT is necessary to combat losses through vomiting and diarrhea. 

o       Intravenous (directly into the blood stream) fluids are necessary in severe cases and the patient must be hospitalized.  This is the puppy’s best chance for a successful outcome.

o       Subcutaneous (under the skin) fluids are not as effective but may be used in less severe cases.  They can be done at home when the expense of veterinary intensive care is prohibitive.

To give subcutaneous fluids, pick up loose skin on the back and pop the needle through, just under the skin. Hang the bag high to speed fluid administration.  Pinch the hole shut and rub that area between your fingers as you remove the needle to keep fluids from leaking back out.  Fluids will make a bulge under the skin and will be picked up slowly into the circulation.  Try to replace the volume of fluid being lost in vomit and diarrhea plus some for maintenance.  Here are some guidelines for reasonable fluid therapy at home:                                                                                                          

PUPPY WEIGHT (LBS.)      CC’S OF FLUIDS EVERY 12 HOURS
5                                           50 to 75
10                                         100 to 150
20                                         150 to 300
40                                         200 to 400
50                                         300 to 500

If the puppy seems to deteriorate at these levels, intravenous treatment is necessary.  If fluids are accumulating at the sides of the chest and even down the legs, stop additional fluids until most of that is gone and then resume at a lower volume.  Stay in touch with your veterinarian if you have questions or if the puppy does not improve.

o       Blood transfusions from a well-vaccinated adult dog or addition of other more extreme fluid therapies may be necessary in some cases to combat shock and actual loss of protein and blood cells.

o       Oral electrolytes help with hydration once vomiting is controlled.  Pedialyte is readily available at pharmacies and can be used at a rate of two to four cc’s per pound body weight per hour depending upon the severity of fluid loss from diarrhea and vomiting.  Large volumes all at one time will stimulate vomiting.  If the puppy vomits immediately after oral fluids, discontinue them until drugs and time have lowered the sensitivity of the stomach. 

·         WARMTH (protect from temperature extremes)

o       A carefully monitored heat pad (on low setting), separated from the puppy by a thick fleece or rug may be necessary for very small patients.

o       Warm fluids by running a portion of the intravenous hose through a bowl of hot water in very depressed, cool puppies.

·         ANTIEMETICS (drugs that block vomiting—provided by your veterinarian) 

·         ANTIBIOTICS (to prevent secondary bacterial infections—provided by your veterinarian)

·         ANALGESICS (for pain control—provided by your veterinarian only in extreme cases because of expense)

·         DEWORMING (may have to wait a bit until the bowel is recovering)

 

FEEDING

     In mild cases, using drugs to block vomiting may be effective enough so the puppy can continue to eat very small meals of bland food.  Science Diet ID, boiled hamburger and rice with the grease completely skimmed off, plain yogurt, and cottage cheese all contain valuable nutrients to keep up the energy of a growing puppy.  Avoid spicy foods like liverwurst, greasy meat, and other high fat foods. 

    We suggest that you give your antiemetic (Cerenia or metoclopromide) and then wait half an hour before first trying to feed your puppy.  If your puppy vomits immediately after eating a very small meal, stop feeding it and continue with the hydration and the drug regimen prescribed by your veterinarian.  When you see 6 to 8 hours without vomiting, you may try another very small snack (a teaspoon to a tablespoon, depending upon the size of your puppy).  If that stays down for an hour, repeat that small amount every hour or two as you accustom the upset stomach to food again.  Offer water or Pedialyte in the same way, just a little at a time, increasing as the puppy is able to keep it down. 

 

DISINFECTION 

     One part bleach to thirty parts water is recommended to kill parvovirus on hard, smooth surfaces that will tolerate bleach (NEVER on a pet).  Unfortunately, that is not an option for your sofa, carpet, or the soil outside in your yard.  In these areas, clean up the actual physical residue as best you can, consider steam cleaning and quaternary ammonium cleaning products with viral capabilities indoors.  Know that parvovirus may stay in the environment a year or more in soil or other porous, difficult to clean surfaces.

     Once your puppy is recovering from parvovirus, bathe it well with antibacterial shampoo, allowing it to soak in the lather for 5 minutes before rinsing.  Repeat a week later.  Make sure that your puppy does not get chilled during its bath.  Be a good citizen by not bringing your puppy around others for a couple of months after its recovery from parvovirus.

 

NEW PUPPY DANGER

     After you have had a puppy with parvovirus on your premises, do NOT bring other unvaccinated puppies into that environment for a year or more!  If you do get another puppy, leave it at the breeder’s facility or farm it out to friends/family until it is at least 4 months old and has had multiple vaccinations against parvo.  For most breeds, we feel pretty confident that receiving the final “puppy shot” at 4 months will be protective.  However, for some of the breeds more prone to parvo, an extra vaccination at 22 weeks (5 ½ months) would give more assured protection.

 

PREVENTION

     Protection from parvovirus begins with the mom.  Many careful breeders booster a bitch’s vaccinations just before breeding her.  This will give her colostrum maximum antibodies against disease.  The mom needs to be in good health to whelp vigorous puppies and to have plenty of milk for them.  Puppies need to get a generous dose of colostrum right away after birth.  Their ability to absorb its protective antibodies decreases to nearly zero by the end of the first 24 hours.

     Antibodies from the mom are living cells pre-programmed to fight specific diseases.  Parvovirus vaccine simulates the actual viral disease.  If we give the vaccine too early (before 6 weeks), the mother’s antibodies from the colostrum attack the vaccine and they inactivate each other.  With time, the antibodies die off naturally.   Since we don’t know exactly when each puppy’s maternal protection gets too low to be useful, we give a series of “puppy shots” that include parvo.  Typically, these begin at 6 to 8 weeks and are given every 2 to 3 weeks, depending upon likelihood of exposure.  Keep puppies away from other puppies or places where dogs congregate during this sensitive period.  We assume in most breeds that the final “puppy shot” is given when the puppy is 4 months old and should protect it from parvovirus.  High risk breeds may opt for another at 22 weeks (5 ½ months) as well.