What To Expect When You Take Your Pet To The Vet
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What to Expect When You go To The Vet If Your Pet has Diarrhea
(Of Course, your vet may do things a little differently)


If you're old enough to be reading this, I'm sure you know that diarrhea (loose or watery stools) is not a disease in itself, but simply a very obvious symptom that something is not quite right with the intestinal system. 

We're so used to having a short bout of diarrhea ourselves, that most people don't get too alarmed when they notice their pet has diarrhea, and rightly so; most of the time the problem is minor and self correcting. 
But sometimes, it's obvious that the problem is more serious, either because the diarrhea has become persistent over the last few days, or the pet is weak and listless, or there are additional problems such as vomiting, or blood in the stool.  In cases like this, it's time to have a veterinarian examine the patient.

Here's what to expect:

First, note that it's helpful if you are able and willing to bring in a recent sample of the diarrhea.  Also, if you've recently used a household cleaner, fertilizer, pesticide, or rodenticide that your pet may have gotten into, your vet will need to know what the active ingredients are; consider bringing in the container so we can see.

We vets see so many diarrhea cases that we quickly gain the experience that often allows us to narrow down the many possible causes within minutes with just a few questions and a good exam. 

On the other hand, other cases of diarrhea take a good deal of detective and laboratory work to figure out.
Diarrhea cases range from very minor to deadly, and from easily cured to terminal.  The diseases associated with diarrhea and the resulting dehydration are easily the largest cause of death in humans and other mammals on this planet. So once it's obvious that the diarrhea isn't just a 1 or 2 day affair associated with eating something inappropriate, we take things seriously.

What follows is how we process a typical diarrhea case and some comments to let you know what we're thinking and why we do various tests and so forth.

History and Signalment:  Signalment might be a new word for you.  It simply means, in veterinary medicine, the basics of what we're talking about: Species, Breed, Sex, Age, and situation.  For example: 1 year old, intact male, lab mix dog who roams the neighborhood.  That signalment will lead us to suspect problems very different than if the signalment were 8 year old, female spayed, indoor cat.

The history is even more critical than in other diseases in helping us narrow down the likely causes. We need to know if your pet ate anything unusual, was boarded or traveled recently, if there were any big stressful events, and we need an honest report of the pet's diet. We also need an accurate vaccination history since so many of our diarrhea deaths are associated with pets that weren't protected with a high quality vaccine program.

A Good Examination:

Your vet will go over your pet from head to toe, getting an assessment of general health, hydration status, circulation problems, GI pain and distress, as well as pick up any secondary problems that might be important.

Frequently, with just the history and exam, your vet may be able to guess correctly that the problem is not too serious and send you home with inexpensive medicines that are likely to solve your pet's problem and discomfort in short order.

But if, because of the history, signalment, or exam, little alarm bells are going off, your vet will recommend a few tests, possible hospitalization, and in some cases aggressive treatment such as IV Fluids etc. 

I'll describe the different tests your vet may recommend in just a minute, but first, let me give you a list that summarizes the different categories of diarrhea based on cause...it's how most of us vets were taught to narrow down a medical case:

Possible Causes of Diarrhea in General Terms:

1.  Viral:  Our most common cause of deadly diarrhea in puppies, with parvo and distemper virus' being the biggest culprits.  I can't emphasize too much how important it is to have your young puppies vaccinated with high quality vaccines. 

While viral diarrhea is most common in poorly vaccinated puppies, it's also an occasional problem in kittens, cats, and dogs too.  Also keep in mind that vaccination programs only protect your pet from the most common viral diseases and the most common strains of the virus; vaccines greatly reduce the chance of succumbing to viral diseases...but not by 100% by any means. 

And not all brands of vaccines are created equal.  It's important to use the newer and better vaccines.  Your vet will be using these.  Your mail order company may not.  For more about vaccine quality go to our page on vaccine recommendations. 

Not to ignore cats;  Feline leukemia, Aids, and Infectious Peritonitis are cat viral diseases that are sometimes associated with diarrhea.  The lab tests and treatment options we have for the different types of diarrhea are discussed a little further on.

2.  Bacterial: Pets frequently take in large amounts of bacteria into their mouth, what with licking everything, eating rancid garbage or "road kill", drinking out of puddles, and grooming with their tongue.  But if your pet is in otherwise good health, free of parasites, on a good diet, and hasn't recently undergone an event stressful to the immune system such as pregnancy or surgery, it's unlikely that much of this bacteria will be able to get past the acidic stomach, the immune system defenses, or the competitive "good" bacteria of the gut in numbers large enough to cause much trouble for long.

You've probably have heard of the bacterias' e-coli, clostridium, and salmonella and the occasional high profile deaths they cause when people get food poisoning at restaurants, church picnics, and the like. 

Well, every once in a while, pets also get food poisoning that becomes more serious than usual.  In addition to food sources, pets can get bacterial infections of the bowels from infected gums, from any diseases or problems that inflame the bowels, and possibly due to long term or inappropriate antibiotic therapy.

Bacterial infections of the gut are sometimes a problem in addition to some other primary problem.  For example, bacterial infections are a common problem in dogs whose intestinal tracts are irritated from parasites or viruses.  As always, your vet won't assume your pet has a single problem.  Like most things in life; "Trouble Likes Company".

3. Parasites: Worldwide, diarrhea due to parasites is a major problem.  But in those countries where people love and care for their pets, and can afford to take advantage of veterinary services, severe problems aren't as common anymore. 

But even with all our new and approved parasite control products, and even if your pet has been taking them, we occasionally get an outbreak of diarrhea due to intestinal worms, protozoa, amoebas, and other parasites.  Like bacteria, microscopic parasites are all around us in our environment waiting to take advantage of any pet whose immune system is weakened.

And the little buggers keep mutating and getting resistant to our medicines!

As an aside; we highly recommend that you follow your vet's recommendations for a parasite control program. Our newest products are safe, flavored, more effective than ever before, and much less expensive than the cost of treating the diseases they prevent.

Another aside; you don't think we do so many fecal sample tests because we like it do you?  Parasites continue to be a big problem despite what I just said praising our newer parasite control products.

4. Garbagitis:  This non-medical term is a used to describe all the possible, inappropriate things that pets sometimes eat, including garbage.  Table scraps that were too rich or spicy, dead animals, sticks, leaves, dirt, underwear, socks, toys, balls, and frequently; plastic wrap.  If your vet suspects that your pet is suffering from GI (gastro-intestinal) irritation due to something like the items mentioned above, he or she may very well give a mineral oil based laxative in hopes of evacuating the bowel.  This sometimes confuses people since laxatives make diarrhea worse, temporarily, and are usually used for constipation, not diarrhea. Another case of "Doctor Knows Best".  Also note, if a foreign body is suspected, your vet will probably recommend radiographs and/or ultra-sound.
Click here to go to our page about Garbagitis ... one of the most common problems we deal with in practice.

5.  Metabolic or Organ Disease:  The various systems in the body are very much inter-related, and diarrhea is often the most obvious symptom of other diseases such as liver disease, pancreatitis, kidney disease, and hormone imbalances.  We become especially suspicious of such diseases in middle age and older pets.  In many situations, your vet will recommend blood work to rule out such diseases.

6.  Diet Related:  A large number of diarrhea cases are solved by switching to special diets that are easy to digest.  Or are non-allergenic to your pet.
Or more consistent or of higher quality.  Once your vet rules out other causes of frequent or chronic diarrhea, he or she may very well recommend a feeding trial of a special diet. It's important to understand, here, that just switching from one brand to the next is unlikely to work...most brands of pet foods contain similar ingredients, any one of which might be causing the problem in your pet.

7.  Hair:  I've listed hair all by itself since it's so often the problem in both diarrhea and constipation...especially in cats.  Many cats and dogs shed excessively and therefore lick and swallow too much hair to digest easily which means the hair ferments in the lower bowel (instead of being digested in the upper bowel) (cheap pet food ingredients cause a similar problem). 

This fermentation process in the lower bowel (similar to humans eating beans) causes irritation to the colon which in turn causes diarrhea.
Anyhow, sometimes the real solution involves reducing the shedding by treating the underlying skin problems, whether it be allergies, poor diet, parasites, inadequate grooming, or deficiencies in fatty acids.
And you may find it interesting that every once in a while cats and dogs groom excessively due to anxiety...like people who chew their nails.  Maybe a case for Prozac!

8.  I'm running out of steam.  So number 8 is everything else:

Such as Cancer, Lymphoma, the secondary affects of chronic diseases, Chronic Bowel Disease, Stress and Anxiety, Fungal, Pancreatic Insufficiency, side effects of certain medications, and probably a few things I've forgotten.

Okay, back on track...What to expect at the vet:

Once the history is established and an initial exam is completed, your vet may have good reason to recommend some tests.  Here's a short description:

Lab Tests and Imaging Techniques Your Vet May Recommend:

I'll make some appropriate comments about each of the following soon...

Fecal test for blood, mucus, and parasites

CBC & Chemistry blood tests

Thyroid Testing

HelioBacter Test

Culture and Sensitivity



Possible Treatments for Less Severe Cases:

NPO:  Nothing by mouth or fasting for 12-24 hours.  This allow the GI tract to "settle down"  Witholding of food and water is a more common treatment for vomiting than diarrhea, actually, but sometimes it helps with diarrhea too.  I usually opt for feeding small amounts of easily digested food (chicken and rice) given in small amounts at a time.

Anti-diarrheals such as kaopectate, pepto-bismol, or amodium-D:  These over the counter products are appropriate for treating at home for minor cases of diarrhea when your pet seems otherwise bright and alert and normal.  If they aren't working after 1-2 days, then you should assume you're missing something and ought to make an appointment with your vet.
These medicines are much more likely to work if you use 2-3 times more than the approved dose, but that brings up a legal problem in the rare event that your pet overdoses.  Note for cat owners: Beware of using the new formula of kaopecate containing bismuth subsalicylate or pepto bismol.  Salicylates such as aspirin can be toxic to cats.  And anything with Tylenol (acetaminophen) can be toxic to cats.

An aside;  This business of using medicines or doses that aren't officially approved by the FDA for a particular species is a common problem for veterinarians.  There are a lot of medicines that we have learned from experience and from our mentors over the years that are usually safe and effective, but have never gone through the expensive process of being approved by the FDA for pets.  Kaopectate and Pepto are good examples of old medicines that we know work better if you give more than the label directions, and that such doses are safe UNLESS the patient is dehydrated sickly, weak, obstructed, or sensitive.  In other words,  we need to examine the pet before we can legally or professionally feel comfortable about giving specific medical advice over the phone..even for simple medications like kaopectate!  And as noted above, cats can be sensitive to even small doses of pepto, the new kaopectate, or Tylenol.

Donnagel or Bella Donna Alkaloids:  Usually more effective than over the counter medicines.  Your vet will prescribe them if needed.  In addition, there are quite a few other anti-diarrheal meds your vet may recommend, including herbals, homeopathic, and familiar products like kaopectate etc.

Lomotil, Loperamide,  or  opium derivatives:  more expensive, usually more effective, and usually reserved for more troublesome cases of diarrhea.  Definitely given under the supervision of your vet.

Actually treating the problem if a specific diagnosis is made such as treating for any parasites found, liver disease, kidney disease etc. Always remember that diarrhea is often just a symptom of some hard to detect disorder, disease, or organ failure

Diet changes are often the solution, especially for pets with fairly frequent diarrhea problems

Metronidazole is a broad spectrum, inexpensive, and safe antimicrobial used to treat the amoebic parasite Giardia .  Maybe more important, this medicine seems to help correct any imbalance in the normal gut flora.  Flare ups of "over-riding" bacteria, protozoa, and amoebas are often associated with diarrhea either as the cause or as a result, so your vet may want to prescribe this medication to your pet.

Prescription Diets: Quite a few cats and dogs with frequent diarrhea respond well to special diets.  We use both Hill's ID (Intestinal Diet) and Royal Canin HE diet with great success

Supportive Care:  Perhaps the most common treatment and most important in serious cases of diarrhea is what we call supportive care.  This means keeping the patient well hydrated, well nourished, warm and comfortable, as well as minimizing symptoms such as fever, nausea, chills, and the diarrhea itself.  IV Fluids are the backbone of supportive care in serious cases.

Antibiotics:  Antibiotics are often used in severe diarrhea cases even when we don't suspect bacteria as being the cause of the diarrhea!  Why?  For several possible reasons:  To prevent bacterial infections of the gut at a time when we suspect the GI tract to be inflamed and vulnerable.  To prevent respiratory, liver, and other organ system infections at a time when we suspect the immune system to be weakened.  And to prevent bacteremia.  Bacteremia is a big deal and refers to bacterial infection of the blood.  It can occur with diarrhea because if the gut wall is inflamed and damaged, then the bacteria that is inside the gut can get across the gut wall into the blood stream.  Once inside the blood, the bacteria will float around the body looking for a place to thrive, which of course, can cause a lot of problems: liver disease, joint disease, heart valve disease, pneumonia, and on and on.

On This Page:

What To Expect When You Go To The Vet If Your Pet Has Diarrhea

More about specific causes of diarrhea and other intestinal problems On Other Pages:

Introduction to Intestinal Problems in Cats and Dogs: 

Parvo Virus
Problems with the Esophagus    
Liver Disease
Food Allergies

Intestinal Problems ... often diarrhea... Associated with Parasites:

Round Worms
Hook Worms
Whip Worms
Tape Worms

Colitis: Chronic problems with the lower bowel... almost always resulting in diarrhea

Garbagitis: Acute intestinal upset due to overeating, eating treats, rancid food, and eating inappropriate objects, or eating too much hair.

Nutritional Treatment and Management of Intestinal Problems

The following is by Dr. Miki King, New London Veterinary Center

Poop. Stool sample. Fecal matter. Bowel movement. Recycled food. Number 2. #*@^.

Nice topic, yes? Why is it that owners frequently forget to bring one in, even when requested to do so?
We hear comments such as "no one told me" (yes, we did), "he didn't go yet" (not in the last few days since you made the appointment?)
(You can save the sample from the day before provided that you keep it refrigerated ),

"but he's had diarrhea" (even more reason to bring in one of those many frequent samples),

"I have two pets and can't tell whose is whose" (watch them when they go.) Most intestinal parasites are contagious. Most times, if pets share the same toilet, they will share the same intestinal parasites.

Bring in the freshest representative sample.

Why does your veterinarian want one?

To check for intestinal parasites : roundworms, hookworms, whipworms, tapeworms, and protozoa. Other specialized tests may also need to be run, dependent on the suspected disease.

Ringworm is a skin fungus, not an intestinal parasite.

Heartworm does not infect the intestinal tract, therefore it cannot be diagnosed in the stool

For the rest of this well written article, go to the Delaware SPCA site where Dr King has a bunch of fun to read informative articles about pet care: 

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Veterinary Pet Insurance

New Kaopectate
a Danger to Cats:

Pfizer has introduced a new formulation of Kaopectate for humans that contains bismuth subsalicylate instead of bismuth attapulgite.

Subsalicylate is an aspirin derivative and just one tablespoonful of the new kaopectate contains 130mg of aspirin equivalent.  The extra strength version contains 230mg.

The maximum recommended safe dose of aspirin for cats is 25mg per kilo which means that a smallish cat (5lbs) given 1 tbls of the extra strength might suffer toxic effects.  Some cats are quite sensitive to salicylates.

So be careful.  

Note: some dogs are also sensitive.

Other Topics on this web site that you might find interesting:
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History of the Discovery of Antibiotics

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Comments & Stories about this topic close to my heart

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Pet Insurance:
Why I like and recommend Pet Insurance

Zoonotics: Diseases People get from Pets, Worms & other Parasites People get from Pets.


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Don't Expect Your Vet to tell you much over the phone:

Let me say that one of our most frequent phone calls is from people who want to know if they should bring their pet in for an exam when their pet has diarrhea (or vomiting).  Or should they treat it at home?

The trouble with questions like this is that it depends on so many variables and that means spending quite a bit of time asking questions. And what we really need to know (hydration status, mucus membrane color, and pulse quality etc) aren't reliably available without an exam.

These types of questions put vets in an awkward position legally too; as soon as we open our mouths with advice, we're potentially legally responsible for the outcome...no joke in this age of lawsuits.

We simply can't diagnose either legally or with much precision over the phone. 

And even if we could diagnose over the phone, to do even a semi good job, we'd have to spend 10-30 minutes asking questions and getting straightforward answers about the pet...time that any good vet can't afford as most of us are up to our eyeballs in minor crisis's at the clinic.

What I tell people who call with such questions is basically what I'm telling you in the introduction at your right...If your pet is eating, bright, alert, and active...and the diarrhea problem has only been going on for 1 or 2 days...Then PROBABLY... but we never know 100%... it would be fine to treat the pet at home.

HOWEVER, don't wait too long; if not getting better quickly or if additional problems like blood or mucus show up, poor appetite etc, then change mental gears and arrange to get your pet to your vet
Fluid therapy is an important part of treating severe diarrhea