Parvo Virus Enteritis-Dysentery

and other virus' that cause
diarrhea in dogs and cats
For the last 30 years or so, Parvo virus has become the number one infectious killer of young dogs.  This page will give you a good general understanding of what to expect if your pet has this deadly disease.


Some brief generalities:

Parvo is a class of virus that affects different species of animals, but the strains of the virus that have evolved in the canine population tend to cause severe and rapid destruction of the intestinal lining. 

This leads to extreme nausea, severe diarrhea, loss of blood into the intestines, absorption of toxins and fecal material into the blood stream, severe dehydration, electrolyte imbalances, and quite frequently a quick death despite aggressive treatment.

Not all parvo cases are alike; some are much more severe than others and the duration of the disease varies from 1 to 7 days; but some puppies that seem fine in the morning are dead that evening. Others slowly get worse over several days and then are "touch and go" for several more days before either dying or recovering.

Parvo can affect dogs of any age, but most frequently causes serious disease in puppies and younger dogs.  It's quite rare in dogs over 2 years old.  However older dogs may be carriers and spreaders of the virus without exhibiting any obvious symptoms.

The virus is dispersed through the stool into and onto kennels, yards, pens, parks and so forth.  This virus remains potentially infective to other dogs for at least a month and apparently for up to 2 years!

Parvo can usually be prevented with a series of high quality vaccinations, but not 100%, and not all vaccines are equal; some are not nearly as good as others.

Treatment if often effective...but often not.  See below.

So PLEASE get your puppies vaccinated starting at 6 weeks of age (sooner if being bottle fed), make sure you don't skip the boosters, and maximize your pet's general health and immune system with high quality nutrtion, parasite control, and loving care.


With few exceptions, this disease is easily preventable.  It simply takes a little effort and money.  In other words; RESPONSIBILITY.

We vets have to watch way too many young pups and dogs die each year to be sympathetic to all the excuses we hear.  Nor am I much impressed with the idea that we simply have "to educate the public".  We've been educating the public for 30 years about this disease. 

Any functional adult knows they're supposed to vaccinate their pets and if they don't exactly know the details, they know all they have to do is call a vet and ask. 

No, thousands of puppies needlessly die because people don't want to take the trouble or spend the money to get their puppies vaccinated.  Another common reason people don't get their pups vaccinated in time is our human inclination to put off stuff despite "good intentions".

I'll skip mentioning my feelings about the socialist baloney about how poor people have "the right to have pets too" but just don't have the money to take care of them.  (Most of these so called poor people I observe seem to arrive in expensive cars, sport expensive jewelry, tattoos, carry cell phones, and so forth.  The only reason they're poor is that they have trouble denying themselves anything, whether it be a cute puppy, a soda, fast food, or easy credit.)

Okay, my apologies and compassion to the genuinely poor and those who are experiencing misfortunes.  But I hate having to watch so many puppies DIE.  If you get a puppy; get it vaccinated.

Back on track:

Each vet has a slightly different recommendation, but in general, your pup is fairly well protected while it is nursing from a healthy mom and for a week or two afterwards.

But your pup is at great risk if you don't start vaccinating starting about 6-7 weeks of age.

A puppy's immune system is fairly weak though until it is about 12 weeks of age, so that first vaccine you get for your pup at 6 weeks of age won't protect your pup much more than 3-4 weeks...and that's assuming you're using the newer improved vaccines.

That's one reason why it's important to get a "booster" vaccination at about 9-10 weeks of age and again at about 14 weeks of age.  Another reason is known as the "booster effect"; expose the immune system to a germ once and the immune response will be so so.  Expose it to the germ several times a few weeks apart and the reponse is usually excellent.  After that, periodic boostering will keep immunity high.  That's why, in general, we recommend yearly vaccination, at least for a few years.

It's fairly important to use the newer and better vaccines.  Vaccine manufactuers are constantly improving their vaccines making them more effective, adapting them to protect against viruses that mutate and change over time, making them less reactive, and so forth.  This is especially true with Parvo.  Your vet, of course, stays on top of this and with rare exceptions will be using the best brands of vaccines...and will be taking all the necessary steps and care to prevent inactivation or contamination of the vaccine. 

You can, if you didn't know it, purchase various brands of parvo and other vaccines from feed stores, pet stores, the internet and so forth, but you have to wonder if these vaccines have been carefully refridgerated, kept from sunlight and so on. 

Do over the counter vaccines contain the newer, improved strains? Are they potent enough?  Are they more likely to cause adverse reactions?  If you give them yourself, are you knowledgable enough to know not to give them if your pet has a fever, pale mucus membranes, and other such details?  A professional exam is pretty important.  Please let your vet do the job.

Bacterial Enteritis
(Infection of the intestines)

The intestinal tract is full of bacteria, but everyonce in a while a "bad" bacteria becomes established in the bowel causing severe inflammation of the gut wall and absorption of toxins and bacteria into the blood stream.

Sometimes the bacteria causing the trouble is not a "bad" bacteria but simply a normal bowel bacteria that "gets out of hand" for various reasons.

Either way, this is a very serious disease.  Treatment involves potent antibiotics and serious supportive care.  These cases are critical and because of the bacteria that gets into the blood also involve vascular inflammation, and at least to some degree, problems with liver, kidneys, and other organs.

One other comment; you have to ask why the patient got a bacterial infection.  There are often underlying problems such as diabetes, nutritional, or immune system abnormallities going on that will have to be addressed.  Occassionally the problem starts because of side effects of medications being used for some other problem.

On This Page:

What to expect if your puppy gets parvo virus

A little about the disease

Preventing parvo

Also a little about bacterial enteritis... a disease that we can be confused with parvo enteritis.

Vocabulary help:

Dysentery refers to extremely severe diarrhea.  Also known as "projectile diarrhea" which conjures up the image of watery diarrhea shooting across the room.

Enteritis refers to inflammation of the intestines

Information about intestinal diseases
On Other Pages:

Intestinal Introduction Page

Problems with the Esophagus

Liver Disease
Food Allergies

Colitis: Inflammatory and chronic problems with the lower bowel

Bad indigestion or "Garbagitis": Acute intestinal upset due to overeating, eating treats, rancid food, and eating inappropriate objects, or eating too much hair.  But be careful... sometimes this is deadly serious.

Diseases people get from pets through worms

Our page about therapeutic diets used to treat diarrhea, constipation, irritable bowel syndrome, enteritis, flatulence, and other intestinal problems.

Intestinal Problems
Associated with Parasites:

Giardia & Cryptosporidia
Round Worms
Hook Worms
Whip Worms
Tape Worms

Get Pet Insurance Before Your Pet Gets Parvo...or any of the other many diseases and injuries lurking out there

What To Expect When You Go To The Vet
(Of course, your vet may do things differently)

History and Exam:  Most puppies and dogs with parvo disease will be weak, and have different degrees of nausea, diarrhea, bloody stool, and look awfully sick.  But in some cases, especially during the first day or two, the symptoms may not be so obvious.  And other diseases can cause similar symptoms ... such as rat poison, food poisoning, hook worms, and other types of enteritis.

Your vet will be looking for additional problems; pups with parvo disease often are also wormy and poorly fed.  And in their weakened state may also be prone to respiratory diseases.

Your vet will also try to determine just how serious your pet's condition is and give you a prognosis: but know that parvo cases can be quite unpredictable ...  treatment may be proceeding well with the pet improving and then suddenly dead, usually due to the absorption of fecal material into the blood stream from the damaged intestinal wall. 

Your vet will evaluate body temp (subnormal temps indicating shock and blood loss are worse than fevers), hydration (dehydration is a major cause of death in this disease) pulse, pupil responses, mucus membrane color (for signs of anemia, jaundice, and toxicity), abdominal pressure, and lymph nodes.  Your vet may also use his or her sense of smell...the damaged intestinal lining associated with enteritis is strong, although NOT exclusive to Parvo.

He or she will want to know about whether or not other pets in your household are affected or vulnerable.  We'll want to know about the patient's vaccine history.

Money:  your vet will probably spend a few moments explaining that

1.  Successful treatment often requries aggressive and intensive care typically costing between $75-300 a day for 2-7 days


2.  Despite such care a fairly high percentage of patients die anyway. 

These deaths are not the fault of the veterinarian; parvo is simply a very deadly disease.  Your vet will have spent a great deal of time and money heroically trying to save your pet and will expect to be paid and appreciated; not confronted with the frequent rebuttal of "I didn't think I had to pay if it died" !

At any rate, we are often successful treating parvo cases, but death rates at most clinics run about30-50%, and successful or not, treatment is fairly expensive.

Lab Work:  Your vet will encourage you to allow at least some of the following:

1.  Parvo test:  we now have accurate, in clinic test kits to confirm our diagnosis.  Remember that there are multiple causes of vomiting and diarrhea.

2.  Fecal test:  for blood (often obvious) and parasites.  Puppies and young dogs with Parvo often have intestinal parasites too.

3.  Urinalysis:  just for information on general health status of the body and as an indicator of dehydration and kidney function

4.  General blood work to check on the health of the other organs and to monitor the immune response, white blood cell response, and to keep track of the anemia that is associated with Parvo.

Treatment:  Whether or not your vet will do some or all of the following will depend on the severity of the case and the budget:

1.  Hospitalization to better allow treatment, intensive care, and monitoring.  Keeping this contagious germ from spreading through the hospital requires some effort and expense, though, so sometimes we treat less severe cases as out patients.

2.  Antibiotics: to minimize and counter bacterial infection of the damaged gut wall and in the blood stream, liver, kidney, and all other tissues and organs being supplied with blood contaminated by fecal material.

3.  IV Fluids:  Dehydration, kidney shut down, and hypo-volemic shock is the number one cause of death and severe weakness in this disease.  Oral, peritoneal, and sub-Q fluids might also be used for various reasons but aren't nearly as effective as IV fluids.

4.  Blood or Globulin Transfusion:  Expensive and not without complications, but sometimes needed to save a life.

5.  Anti-nausea medications:  Your vet will try to minimize vomiting using a choice of different injectable, suppository, and oral medications depending on the severity of the case and the budget.

6.  Anti-diarrheal medications:  Severe diarrhea is weakening and your vet will try to stop or slow down the diarrhea using various types of absorbents, anti-spasmotics, and so forth. 

I like using activated charcoal on parvo cases. It helps with both the diarrhea and toxin absorption.

7.  Nutritional Support:  This differs quite a bit from vet to vet, but theres a lot of evidence that despite having a raw gut, parvo patients recover better if fed.  We have various methods of accomplishing this while avoiding vomiting to include tube feeding.

8.  Anti-Serums:  One of the major secondary problems of Parvo is the bacteria that gets into the blood stream from the damaged gut. This causes a sometimes deadly reaction generally known as "Toxic Shock".  There are anti-serums (made for horses and not officially approved for dogs) available that we think help counter this problem.  Fairly expensive and unapproved, so your vet may or may not offer this.

9.  Lots of nursing and supportive care.  And quite a few additional, "alternative" and "complimentary" treatments

10.  Steroid use:  As usual, steroid use is controversial with the negative being that steroids cause immune suppression, reducing the body's ability to fight off infection.  On the other hand, steroids are wonderfully effective at reducing inflammation, vascular leakage, and shock.  I think the benefits out weigh the negatives.  Other vets may disagree

11.  Immune Stimulation:  Some vets are experimenting with various non-conventional treatments designed to stimulate or support the immune system.  I'm not sure how successful or helpful this is likely to be.

12.  Referral:  Some vets may recommend referral to a bigger clinic or referral center if your pet needs around the clock or intensive care.

13.  Aftercare:  If your pet survives, you need to understand that for a week or so the patient's immune system will be weak and the patient extra susceptible to additional problems, respiratory diseases, and so forth.  Your vet may recommend post recovery antibiotics, special diets, and supplements.

14.  Vaccinate:  As soon as your pet has had a week to recover, return to your vet to vaccinate.  Booster again in about a month.

Other Virus' that cause Diarrhea in Dogs and Cats

coming soon...

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