Answers and Discussion

Answers and Discussions to the Questions:

• How is parvo spread and what areas of the body does it affect?
  
  Parvo is shed in the feces so the fecal-oral route of transmission is most common.   However, it is also likely that the saliva and vomitus contain viral particles.   In any case, CPV replicates in rapidly dividing cells, like those of the lymph nodes, spleen, bone marrow and intestines.  In the intestines, the virus kills the germinal epithelium of the intestinal crypts, leading to epithelial loss, shortening of intestinal villi, vomiting and diarrhea.  In lymph tissue, there is necrosis and destruction of myeloproliferative cells, leading to lymphopenia or in severe cases, panleukopenia.
  
• What clinical signs do you see with parvo and what other differential diagnoses must you consider?
  
  Clinical signs include lethargy, anorexia, depression, vomiting, diarrhea (may be yellow-gray to bloody), and fever (104-106 F).  Other differentials should include Salmonellosis, Campylobacteriosis, E. coli infection, coronavirus infection, canine distemper or other enteric viruses.  CPV infection may also be confused with hemorrhagic gastroenteritis (HGE), although HGE usually resolves within 24 hours.

• How do you diagnose parvovirus infection?
  
  CPV is most easily diagnosed with a fecal ELISA.  However, if the test is negative and parvo is highly suspected, wait 48 hours and run the test again.  The virus is not shed until after day 3 and so it may be too early to test the feces.   Also, modified live CPV vaccines shed in the feces may give a false-positive result 4-10 days after vaccination.  Make sure to have a good amount of feces when running the ELISA--watery stools may dilute the antigen and give a false-negative result.   Conclusive proof of CPV infection, however, is made with electron microscopy.

• What treatments would you institute for "Stinky"?

First stop all food and water intake if the patient is still vomiting.   Fluid therapy is very important.  A crystalloid fluid, like Normosol with 20 mEq/L potassium chloride added, is a good choice.  Fluid losses (diarrhea and vomiting) should be replaced also.  The easiest way to do this is to estimate the volume of the loss, then double it and give the animal a fluid bolus of that amount.   Secondly, a broad-spectrum antibiotic should be given.  Either a first-generation cephalosporin or ampicillin/enrofloxacin combination is commonly used, or some vets may use gentamicin and amikacin in severe (septic) cases.  Antiemetics may be necessary.  Metoclopramide is best (1-2 mcg/kg/hr IV CRI or 0.2-0.4 mg/kg SQ TID).   If albumin is low or total solids are dropping, a plasma transfusion or hetastarch can be given. 

• What parameters should you monitor for the next few days?
  
  Monitor body weight to make sure it is not decreasing.  If fluids are being supplemented correctly, body weight should increase to account for rehydration.   Monitor for overhydration by measuring central venous pressure and ausculting the chest often.  Blood glucose should be monitored at least QID for the first couple days.  If it continues to decrease, 2.5-5% dextrose should be added to the fluids.   The animal's glucose will then start to increase after sepsis is resolved.  If vomiting has stopped, start the patient on small amounts of water.  If that is held down for at least 12 hours, a bland gruel (rice or boiled chicken) should be fed or use a commercially-available special GI diet.

• What should you tell the client about cleaning the household environment?
  
  Clean contaminated areas with bleach and allow a prolonged contact time.   Vacuum all other surfaces (carpet, furniture).  Wait at least a month before bringing a new pet into the house.  It would be better if the new pet is an older puppy who has been properly vaccinated.

• Regarding parvo vaccines, what is the recommended vaccination schedule for dogs?
  
  Combination vaccines (parvo/distemper) should be given at 8, 12 and 16 weeks of age; boostered at 1 year old, then given every 3 years.  Certain dog breeds are more susceptible to parvo infection than others, including rottweilers and dobermans.  It is recommended that clients vaccinate at-risk breeds one more time at 20 weeks of age.

• Follow-Up: "Stinky's" owner elected to donate her to the hospital due to financial difficulties.  She remained in the critical care unit for a few days but despite treatment, she became aneutrophilic and continued to have vomiting and diarrhea with mucosal sloughing.  Due to the poor prognosis, she was euthanatized.

Canine Parvovirus Pearls

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Copyright 2000, Wayne E. Wingfield, and Brenda McClelland, DVM Colorado State University   
This page was last edited:  03/01/00