Vomiting and Diarrhea in Dogs and Cats: An Expert Guide

Pets commonly suffer from upset digestive systems. But sometimes vomiting and diarrhea in dogs and cats can indicate a serious illness.

Cat looking sick
Vomiting and diarrhea are no fun for anyone. Photo: Samuel Cockman

Vomiting and diarrhea in dogs and cats are common issues that many pet owners face. While these symptoms can often result from minor digestive upsets, they can also indicate a more serious health problem. Understanding the causes and knowing when to seek veterinary care is crucial for your pet’s well-being.

Understanding Your Pet’s Digestive System

To better understand the causes of vomiting and diarrhea in dogs and cats, it’s useful to have a general idea of your pet’s digestive system and how it works.


The digestion process begins when your dog or cat chews food. Saliva mixes with the food, and an enzyme in the saliva begins to break down the starches. Saliva also lubricates the chewed food, making it easier to pass through the digestive system.


The chewed food then travels to the stomach via the esophagus. Peristalsis, a process of muscle contractions, pushes the chewed food down the esophagus and into the stomach.


In the stomach, the chewed food’s proteins are broken down by pepsin, a secretion from the stomach lining. Hydrochloric acid further breaks down the food for easier digestion. The food remains in the stomach for one to two hours, where muscles keep it moving among the acid and pepsin before it passes into the small intestine.

Small Intestine

The small intestine, a long muscular tube, consists of the duodenum, jejunum, and ileum. The gallbladder releases bile, and the pancreas releases digestive enzymes to further break down fats, sugars, starches, and proteins. Nutrients are absorbed through the lining of the small intestine, and the leftover waste passes to the large intestine.

Large Intestine

The large intestine, or colon, pushes waste through to the rectum, absorbing excess moisture. The feces are then expelled from the body.

Causes and Symptoms of Vomiting in Dogs and Cats

Common Causes of Vomiting

Vomiting in pets is typically caused by an irritant in the stomach or the duodenum. Common causes include:

  • Human Foods: Greasy foods can cause irritation, leading to vomiting.
  • Foreign Objects: Items such as bones, sticks, or plastic can cause irritation or obstruction.
  • Viral or Bacterial Infection: Pets can get infections that require medication.
  • Parasites: Roundworms or hookworms can cause vomiting as the body tries to expel them.
  • Serious Illness: Cancer, liver disease, or kidney disease can lead to vomiting.
  • In the following video, you’ll learn much more about the reasons cats throw up:
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What to Look For in Vomit:

An examination of the vomit can provide clues as to the cause.

  • Red blood in your pet’s vomit indicates bleeding of the digestive tract relatively close to the esophagus.
  • Darker blood that has the appearance of coffee grounds indicates blood farther down the digestive tract.
  • Vomit tinged with yellow bile may indicate an irritation in the first section of the small intestine; it can also indicate that the animal’s stomach is empty.
  • White substances, particularly those with a spaghetti-like appearance, indicate parasites.

Next, we’ll take a much closer look at this condition — first in cats specifically, and then in dogs.

Vomiting in a cat may be either directly related to the gut or a secondary symptom of another issue. Photo: kiandthemags

Why Is My Cat Vomiting?

Is your cat a “happy vomiter,” or is it something more serious?

Some cats are “happy vomiters,” meaning they’re just doing what cats do and there’s nothing pathological about it.

But vomiting can be a sign of significant illness, so how do you recognize when a problem is minor or quite major?

Identifying Why Your Cat is Vomiting

It can be tricky to spot the difference between vomiting, retching and regurgitation.
But knowing the difference helps your vet target the most appropriate tests.

Partially digested food is ejected from the stomach. Signs include:

  • Salivation and drooling
  • Lip licking
  • Restlessness
  • Abdominal heaving
  • Vomited bile or a large volume of partially digested food

This is food that doesn’t get as far as the stomach and sits for a while in the gullet. Signs include:

  • Little effort is involved — sometimes the cat just lowers his head
  • A sausage-shaped offering
  • No signs such as restlessness, lip licking or drooling

Also known as “dry heaving,” this involves reverse stomach contractions. Signs include:

  • Little abdominal effort
  • No excess salivation
  • Only a small volume of vomit is produced

Common Causes of Vomiting in Cats

There are many reasons cats vomit, but for starters, it’s helpful to know if the problem is “primary” (directly related to the gut) or “secondary” (vomiting is a symptom of a problem elsewhere in the body).

Primary Causes:

  • Infection: This could be due to causes like feline distemper or campylobacter.
  • Toxins: That “bad” mouse or toxins in spoiled food could be the culprit.
  • Inflammation: A common cause is hair rubbing around inside the stomach.
  • Ulcers: Perhaps a medicine damaged the cat’s stomach lining.
  • Cancer: Though uncommon, gut cancers can cause sickness.
Drooling is a telltale sign of vomiting and not of retching or regurgitation. Photo: gregwalters

Secondary Causes:

  • Pancreatitis
  • Liver diseases, such as cholangiohepatitis
  • Kidney failure
  • Overactive thyroid glands
  • Urinary blockage

The more signs you pick up on, such as excessive thirst, weight loss and poor appetite, the more likely it is the cat has an underlying problem that needs treatment:

  • One example might be irritation of fur in the stomach (hairballs) — this cat would need no intervention other than more regular brushings.
  • However, a cat with a recent history of taking arthritis medication or losing weight needs to be taken more seriously.

What Should You Do?

If your cat seems otherwise well and has vomited, take away food for 24 hours but leave fresh water. Reintroduce a bland diet after 24 hours if no further vomiting occurs.

When Is a Vet Trip Essential?

If you’re unsure what to do, take a look at this list. If you recognize any of these signs in your cat, see the vet:

  • Repeated vomiting: If this goes on for more than 4 hours, contact the vet.
  • Dehydration: If the cat can’t hold down water, there’s a risk of dehydration.
  • Losing fluid in diarrhea: Sickness and diarrhea makes dehydration more likely.
  • Blood in the vomit: This is a sign of internal bleeding and should not be ignored.
  • Dullness or lethargy: A cat who seems unwell or withdrawn could have gut pain.
vomiting and diarrhea in dogs image
If foreign bodies, such as pieces of stick, enter your dog’s gut, this may cause the dog to vomit. Photo: Fake Plastic Alice

Vomiting and Diarrhea in Dogs – Causes and Solutions

One of the biggest differences between cats and dogs is that cats leave their vomit for their human to clear up, while dogs will gobble it up in the length of time it takes to fetch cleaning stuff.

Vomiting vs. Regurgitation in Dogs

Vomiting: Active process with abdominal heaving.
Regurgitation: Passive process with little effort.

Pro tip: If you suspect your dog is regurgitating, record a video of it and show it to your vet.

Factors outside the gut can make a dog nauseated or cause vomiting. Some examples include:

  • Pancreatitis: Digestive juices escape from the pancreas and cause severe inflammation. This can be linked to a recent fatty meal.
  • Liver disease: When the liver fails to thoroughly detox the blood, the dog slowly poisons himself.
  • Pyometra: Pus in the womb causes bacterial toxins to enter the bloodstream.
  • Kidney failure: The kidneys fail to remove naturally occurring toxins from the blood, which build up and inflame the stomach lining.
  • Inner ear problems: When the balance mechanism is inflamed or infected, this results in nausea, similar to motion sickness.
  • Complicated diabetes: Ketone buildup leads to nausea and vomiting.
  • Addison’s disease: Severe electrolyte imbalances in the bloodstream cause vomiting.
  • Bladder obstruction: Retention of toxic metabolites cause nausea and vomiting.

Even this isn’t straightforward, as this list of possible causes shows:

  • Garbage gut: Scavenging spoiled food that the body then “rejects.”
  • Stomach infections: Food poisoning by any other name.
  • Systemic infections: Bugs such as distemper, parvovirus, coronavirus and leptospira cause the entire dog to become ill, of which gut signs are a part.
  • Stomach ulcers: Due to stress or caused by drugs eroding the lining of the stomach.
  • Inflammatory bowel disease: The causes of inflammatory bowel disease are a whole topic to itself. In a nutshell, this can be food allergy or intolerance, lack of fiber in the diet or stress.
  • Drug or toxin reaction: Anything that has contact with the gut wall has the potential to cause inflammation and vomiting.
  • Cancer: From localized tumors to general inflammation of the intestine, cancer is a rare cause of vomiting — but not one to be overlooked.
  • Foreign body: This one causes most vets the biggest headache. It is the nature of dogs to investigate with their mouths and to chew. This can lead to swallowed toys, yogurt pots, stones — you name it. If these get stuck in the gut, then the consequences can be very serious.

What to Do When Your Dog Vomits

If your dog seems otherwise well but has vomited, then withhold food for 12–24 hours, but allow access to water. Reintroduce bland food after the fasting period.
See a vet if there is blood in the vomit and if vomiting lasts longer than 4 hours, or if the dog shows other symptoms like lethargy or diarrhea.

Indeed, take the dog to a vet if you see the following:

  • Blood in the vomit
  • Vomiting for longer than 4 hours
  • Unable to keep water down
  • Listless or lethargic
  • Also has diarrhea
  • Trying to be sick but bringing nothing up
  • Has other symptoms apart from vomiting

As you see, the reasons for a dog throwing up are many and varied, so for safety’s sake, hand the problem over to your vet.

When your dog experiences symptoms beyond vomiting, like lethargy and diarrhea, it’s time to see the vet. Photo: Kate Brady

Diarrhea in Dogs and Cats: Causes and Treatments

Diarrhea in pets usually results from an irritant occurring at the end sections of the small intestine or in the large intestine.

Because the digestive process hasn’t been completed, the moisture has not been removed from the feces, which is why it is expelled in a very liquid state.

Common Causes of Diarrhea

  • Parasites
  • Foreign objects
  • Food irritants

Fat and skin from human scraps are often a cause of diarrhea in dogs, and shouldn’t be fed to pets, according to Dr. Carol Osborne, DVM.

She states, “If you’re not going to eat it, neither should your dog. You’re not going to eat the fat and many of you aren’t going to eat the skin or the scraps.”

Fat is harder for cats and dogs to digest, which can cause irritation in the colon resulting in diarrhea.

An obstruction in the lower end of the small intestine or in the colon can also cause diarrhea; an obstruction in this area of the digestive tract often causes small amounts of blood to be expelled rather than feces.

A puncture of the bowel caused by an obstructed object can cause the toxic contents of the intestines to spill into the abdominal cavity, causing a serious and sometimes fatal condition known as peritonitis.

In the following video, a veterinarian discusses the causes, symptoms and treatment of diarrhea in pets:

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Identifying Diarrhea in Pets

If your cat or dog has diarrhea, examining the feces may give clues as to the cause.

  • Expelled foreign objects: Such as fabric or plastic.
  • Parasites: Appear as white, noodlish objects.
  • Red blood and mucus: Indicates injury to the colon.
  • Black, sticky feces: Suggests injury in the duodenum.

If your cat or dog’s vomiting or diarrhea lasts for several days, you should bring your pet to the vet to have a thorough examination to determine the exact cause.

Next, we take an even deeper look at this common condition in dogs specifically.

Diarrhea may be a symptom of intestinal parasites. Photo: alecale35

Recognizing the Warning Signs of Dog Diarrhea

  • Blood in diarrhea: Seek urgent veterinary attention.
  • Vomiting and diarrhea: Risk of dehydration.
  • Restlessness or pain: Indicates severe illness.
  • Diarrhea lasting more than 48 hours: Needs treatment to restore gut balance.

Managing Uncomplicated Diarrhea at Home

OK, so your dog has a history of scavenging, and they raided the garbage yesterday.

Now, are they bright and well, not vomiting, and asking for food? Good. If you aren’t unduly concerned for their overall health, here’s what you should do.

Monitor your dog for signs of lethargy. Photo: Free-Photos

Yep, that’s right. Withhold food for 18–24 hours.

This allows the gut to purge itself without adding “ammunition.” It also rests the bowel, allowing it to heal itself. Of course, during this time, allow free access to water so the dog doesn’t become dehydrated.

The purpose of starvation is twofold:

  1. Food causes muscular contractions of the bowel, with the effect that it “feeds” the diarrhea. When you withhold food, those muscular contractions ease and allow things to calm down.
  2. There’s evidence that feeding when the gut is inflamed is linked to the development of food allergies. Thus, if you offer Riffraff his regular food when his tummy is upset, there’s a small risk at a later date he’ll develop an allergy to one of the ingredients.

All being well, the dog “empties” and then doesn’t “go” for a while (their system is empty).

Reintroducing Food
The 2 rules for reintroducing food are:

  1. Little and often
  2. Bland food

Bland foods, such as white meats (chicken, white fish, turkey and rabbit), with an easy-to-digest carbohydrate (boiled potato, white rice or white pasta) are gentle on the gut, aiding its recovery.

Giving small meals regularly, such as 4–6 portions spread over the day, helps keep things low-key. Remember: The more the stomach is stretched (with a big meal), the greater the muscular contractions with the potential to rekindle diarrhea.

As a rule of thumb, feed the bland diet for 4–5 days. Once the dog has passed a couple of formed poops (albeit small ones because the food is highly digestible), take several days to slowly reintroduce the regular food.

Home Remedies
So far, we haven’t mentioned pumpkin.

This is wonderful stuff that can ease constipation and firm up soft stools. This is down to the soluble fiber content, which helps regulate the gut and reset it to normal.

If you feel inclined, it’s fine to add a little pumpkin to the pet’s food and give nature a helping hand.

The other “goodies” that can help reset the bowel are probiotics.

When dogs have diarrhea, they lose some of the helpful bacteria that are necessary for digestion. Indeed, prolonged diarrhea results in a swing the other way, where harmful bacteria get the upper hand and keep the diarrhea going.

Feeding a good dog probiotic (and yes, it does have to be a dog formulation — your human probiotic yogurt drink isn’t going to help because we have different gut bacteria) once a day for 3–5 days can speed up recovery.

Avoiding Diarrhea

You can also help your dog by cutting down on some of the risk factors for diarrhea, such as intestinal worms or infections against which there is a vaccine.

Regularly deworm your dog according to their individual risk:

  • For example, if you have a hunting dog who regularly eats carcasses, then weekly or monthly deworming would not go amiss.
  • However, a lapdog who lives mostly indoors should be fine with 3–4 times a year.

Keep up to date with your dog’s vaccinations, and if you are going on a vacation out of your usual area, speak with your vet about whether non-core vaccinations are advisable.

A sudden change of diet can also upset stomachs. If you want to change foods, take a few days to make the swap, gradually mixing in more of the new food and using less of the old.

Hopefully, you now feel more confident about how to handle those tummy upsets. Whether your pet needs to see the vet or can be managed at home, here’s a big “Get well soon” from us.

The cause of dogs suffering from bloody stools often remains unknown. Photo: smerikal

Blood in the Diarrhea — And What It Means

The color red. Red lights. Red alert!

Red means bad things. When your dog poops red, that’s a scary thing.

Many dogs will show an occasional speck or a drop of blood while defecating. This should always be checked out.

But some dogs, often without a history of being sick, have very bloody diarrhea that can set people into panic mode.

Causes of Bloody Diarrhea

Seeing bloody stools in a dog is a horrible topic to discuss. You wake up stepping in something awful or you suddenly see your dog has very bloody diarrhea while you’re on your morning walk.

  • Infections: Such as parvovirus or bacterial infections.
  • Foreign Objects: Causing injury to the digestive tract.
  • Severe Illness: Such as cancer or severe liver disease.

Questions Your Vet Will Ask

  • Has your dog been having diarrhea?
  • How long has the diarrhea been going on?
  • Is there any vomiting?
  • How long has there been blood in the poop?
  • Has he still been eating?
  • Is he lethargic?
  • Has this ever happened before?
  • Does your dog roam free?

Diagnostics and Supportive Care

Your vet may want to do some blood work, a fecal exam and radiographs if indicated.
Diagnostics and treatment depend on how debilitated your dog is and the level of dehydration. Many of these dogs are looking great even though their stool looks like a horror movie.

We often don’t find the reason behind an acute outburst of bloody diarrhea in a dog. If the bloody diarrhea occurred acutely and the dog has been otherwise in good shape and is not acting sick, we usually treat it with supportive care.

The good news is that these dogs usually get better as fast as they have become sick.

No one really wants to talk about bloody stool, but your dog should get to the vet immediately if you see it. Photo: abbynormy

Treatment may mean a short stay in the hospital for fluids and medications by injection, but many of these dogs can be sent home under your careful watch.

Treatment usually includes a short fast followed by small amounts of a bland diet for several days, medications to control GI signs, and monitoring of the dog’s demeanor and symptoms.

Hemorrhagic Gastroenteritis (HGE)

Some dogs exhibiting bloody diarrhea are also extremely sick and are suffering from a more serious form of bloody diarrhea called HGE. These pups usually exhibit:

  • Profuse, foul-smelling, bloody diarrhea
  • Poop that people describe as “raspberry jam” (culinary pathology is always gross but informative)
  • Anorexia and vomiting
  • Depression and abdominal pain
  • Dehydration

Diagnosing HGE
The physical exam, history and a quick blood test in the office — called a packed cell volume, or PCV — can differentiate HGE from a less serious attack of bloody diarrhea. Dogs with HGE require hospitalization, IV fluid therapy and more supportive care. They are very sick pups indeed.

Reduce Stress

  • Stress may play a part in diarrhea cases.
  • Boarding your dog can also lead to diarrhea, bloody or otherwise.
  • Rich foods or trash eating can certainly be a factor.
Diarrhea is just one symptom of cobalamin deficiency in dogs. Photo: colliefreund

How Cobalamin Injections May Help with Diarrhea

Roy’s Struggle with Persistent Diarrhea

Roy, a Rough-Coat Collie, was having a decidedly rough time with persistent diarrhea.

His caretaker had invested in blood tests and followed advice to date, and yet Roy was still sloppy in the stools department — and his person was getting impatient.

It wasn’t that we didn’t know what was wrong with Roy. He had inflammatory bowel disease.

His treatment involved:

  • A hypoallergenic diet: This drastically reduces the risk of food intolerance or allergy as a trigger for the lining of the bowel to become inflamed.
  • Pre- and probiotics: The nature of Roy’s diarrhea meant he had lost most of the bacteria helpful to digestion, and these needed replacing.
  • Antibiotics: Where the normal gut flora and fauna had been lost, other bacteria had invaded and flourished. The trouble was that these bacteria don’t help digestion and had to be gotten rid of so that healthy gut bacteria could flourish.
  • Steroids: The severity of Roy’s inflammation meant that he passed blood. This severe soreness needed settling down with anti-inflammatories, of which steroids were the first choice.

With Roy still in the doldrums despite the diagnostics and treatment, it looked like we’d have to add in an even stronger anti-inflammatory medication. But Roy’s human was unhappy and didn’t like the idea.

It has long been recognized that cobalamin is essential for good bowel health.

Decades ago, for a dog with an upset stomach, vets often gave a shot of cobalamin to speed recovery. However, in the push for evidence-based medicine (EBM), this practice was stopped as “old school,” as it was anecdotal at best rather than based on hard evidence.

In a spirit of what goes around comes around, Roy was given an injection of cobalamin and asked to return the following week.

Only 3 days later, Roy’s human called, ecstatic on the end of the line. After weeks of horrid poop, that very morning Roy had passed a minor miracle of a perfectly formed poop. Whoop-whoop!

Reassessing our plans, we elected to give Roy 6 weekly cobalamin injections and then review his therapy after that.

A new nutraceutical tablet contains cobalamin in a form the gut can absorb when blood levels are low. Photo: sayuraam

Why Cobalamin Matters

The news gets better and better because cobalamin is actually a vitamin — Vitamin B12, to be precise.

This is a water-soluble vitamin and has several important roles in the body, including:

  • DNA synthesis
  • Fatty acid metabolism
  • Cell metabolism
  • Making new red blood cells

Symptoms that a dog with low cobalamin might show include:

  • Poor appetite
  • Anemia
  • Diarrhea
  • Vomiting
  • Failure to thrive
  • Dull, starry coat

As you can see, this humble vitamin is actually very important.

What Low Blood Levels Mean

When blood levels of cobalamin are low, then gut health dips and the dog is less able to absorb the goodness from food. When the bowel wall is healthy, it can process Vitamin B12 and absorb it.

Happily, there are lots of B12-rich foods out there, but in an ironic twist, it turns out that an unhealthy gut is least able to absorb the cobalamin. Worse than that, cobalamin only lasts half as long when the dog is deficient — talk about adding insult to injury.

In dogs, only 1% of the cobalamin in food is absorbed across the bowel wall by diffusion. Instead, to get cobalamin from the gut lumen into the blood depends on a special transport system in the last part of the small intestine.

At this location are special molecules that bind to cobalamin in the gut lumen and help transport it across the gut wall.

Unfortunately, this mechanism breaks down, like a car with an empty fuel tank, when blood cobalamin levels fall, meaning the body is less efficient at the very thing it needs to do.

This means that feeding a cobalamin-rich diet, while commendable, is unlikely to help very much.

The Answer: Systemic Cobalamin Administration

Giving cobalamin systemically, in the form of weekly injections for 6 weeks can tip the scales and get things going again.

Once the blood levels are raised, then the gut transport system for cobalamin starts working and everything starts to swing again.

The injections can sting, and occasionally patients develop a sterile abscess at the injection site, but these issues aside, there are no major side effects. However, it’s a fair bet the dog would prefer not to visit the vet every week for over a month.

Thankfully, there’s good news on the horizon:

  • For the first time, there’s a nutraceutical tablet available that contains cobalamin in a form the gut can process and absorb when blood levels are low.
  • You can give the supplement (Cobalaplex, made by Protexin) to the dog once a day at home and avoid the dreaded vet trips and needle.

Roy’s Tail Is Still Wagging

The great news is that Roy is still doing so well that we’re weaning down the dose of his steroids.

He’s maintained a solid poop on the hypoallergenic diet alone, now that the allergens have gone, and his bowel health is top-notch.

Of course, if your dog has diarrhea, then see the vet. But it is heartening to know that a simple vitamin may be what’s needed.

So if your dog has a tummy upset or even long-term diarrhea, spare a thought for the B vitamins — they could help turn the corner.

In the next section of this article, we’ll discuss long-term diarrhea.

Parasites and food allergies are just 2 of the many possible culprits behind long-term diarrhea in dogs and cats. Photo: marczero1980

Long-Term Diarrhea in Dogs and Cats

Diarrhea is a symptom rather than a condition in its own right.

So when it comes to treating such cases, getting to the bottom of things to find the underlying cause is crucial.

If we can find the cause and treat it, we can improve both the pet’s and your quality of life.

Common Symptoms of Long-Term Diarrhea

Signs of diarrhea are self-explanatory: loose or liquid motions rather than a nice, firm, sausage-shaped stool.

Put simply: If you can’t pick it up easily, then it’s diarrhea.

If your dog has diarrhea, here’s a quick plea from a veterinarian: Take a look. It really helps to know if blood or mucus is present.

If you are really keen, there is even a Bristol stool chart that ranks feces on a scale from 1 to 7 for consistency (1 is rock-hard nuggets; 7 is completely liquid), which is all valuable information when it comes to deciding on the best course of treatment.

Common Causes of Long-Term Diarrhea

The causes of diarrhea are many and varied.


  • Food allergy or sensitivity
  • Bacterial infections (salmonella, campylobacter, etc.)
  • Parasites (worms, giardia, coccidian)
  • Inflammatory bowel disease (IBD)
  • Small intestinal bacterial overgrowth (SIBO)
  • Low cobalamin (Vitamin B) levels in the bowel wall
  • Lymphoma (bowel cancer, which is more likely in the cat)
  • Protein-losing enteropathy (PLE)
  • Eosinophilic enteritis

Disease outside the bowel:

  • Exocrine pancreatic insufficiency (EPI)
  • Low protein levels in the blood
  • Pancreatitis
  • Liver disease
  • Severe heart failure
  • Stress
If your pet’s loose stool doesn’t improve after a few days, see the vet — the cause may be more serious than you think. Photo: eiriknewth

Diagnosis and Treatment

There are so many causes of diarrhea that investigation requires a logical approach.

Your vet will take a detailed history and an account of the pet’s age and breed, recent changes of diet and contact with infectious agents.

If a puppy has long-term diarrhea, the immediate suspect may be a parasitic infection, and the most useful diagnostic test is fecal analysis. By looking for parasites, eggs and larvae under the microscope, sometimes a diagnosis is made, and appropriate treatment is started swiftly.

Adult animals with diarrhea fall into 2 groups:

  1. Self-limiting cases that get better in a few days
  2. Those with long-term diarrhea

Long-term diarrhea tends not to be straightforward, and a screening blood test may help rule out disease that is causing it.

If the panel and fecal analysis are normal, then next on the list is a blood test looking at bowel function. This checks that the pancreas is producing enough digestive enzymes, the bowel is not deficient in cobalamin (essential for healthy digestion) and there is no overgrowth of bacteria within the bowel lumen.

If these tests draw a blank, then either an ultrasound scan or an endoscopy may be appropriate to reach a diagnosis.

Ultimately, in hard-to-crack cases, a bowel biopsy should give a definitive answer, but this procedure is not without risk and should be discussed thoroughly with your vet first.

The key to treatment is identifying the reason for the diarrhea and addressing that issue.

These common conditions require the following treatments:

  • Food allergy: Hypoallergenic diet
  • Parasite infection: Fenbendazole (depending on the parasite)
  • SIBO: A corrective course of antibiotics
  • EPI: Supplement the pancreatic enzymes
  • IBD: Anti-inflammatory drugs, low-allergen diet
  • Lymphoma: Surgery and possibly chemotherapy


To prevent long-term diarrhea, seeking veterinary advice in the early stages is key. When ignored, a short-term tummy upset can become a long-term problem if the bowel’s natural balance becomes disturbed and its ability to digest food is knocked out of whack.

So if simple diarrhea doesn’t settle after a couple of days of a light diet, take your pet to the vet to get checked out.

My girl had not 1 but 4 types of infections that gave her diarrhea. Photos: Pippa Elliott
This Puggle had not 1 but 4 major problems that gave her diarrhea. Photos: Pippa Elliott/Petful

Common Infections That Can Cause Diarrhea in Puppies

This section of the article was written by Dr. Pippa Elliott, BVMS, MRCVS.

As someone with a Puggle puppy, I’m all too familiar with poop.

My new fur-family addition came with several unwanted extras in the tummy department in the form of campylobacter, roundworms, tapeworms and giardia.

Well, 2 fecal analyses and 3 courses of treatment later, I’m relieved to say she now passes PFPs (perfectly formed poops).

A History of Infections
My puppy didn’t have the best start in life and picked up her infections by contact with feces in the unhygienic conditions she lived in. When dogs come into contact with poop, they can catch all sorts of diseases, especially the very young whose immune system isn’t strong enough to protect them.

My recent experience of anxiously awaiting the next bowel movement to see if there was any improvement helped me view puppy tummy upsets from the other side of the consulting room table.

It has taken nearly 4 weeks to go from bloodstained, mucoid diarrhea to PFPs, so have a little patience if your puppy’s poops aren’t perfect yet despite a course of treatment. It can take a while to get to the bottom of things because your pup might have more than 1 infection (or 4, in my pup’s case).

Worm Infections

Worms are top of the charts when it comes to puppy poop infections.

  • The granddaddy is roundworms (Toxocara), with the mother passing larvae onto her pups in the womb and via her milk. It’s safe to assume your pup has Toxocara and to worm repeatedly — those larvae hatch out regularly, especially during the first 6 months of life.
  • Tapeworms (Dipylidium) go hand in hand with fleas, so the pup with passengers of the jumping sort is almost guaranteed to have tapeworms. The worms in the gut produce egg packets that migrate out of the pup’s anus and causes extreme itchiness, so be vigilant to the bottom-obsessed youngster constantly scooting or trying to chew under the tail.
  • Whipworms (Trichuris) and hookworms (Ancylostoma and Uncinaria) are also common and easy to catch. The eggs are extremely hardy and can survive for years in the environment, so it’s easy for a puppy to accidentally pick up infection. The signs include watery, bloody diarrhea, with the diagnostic challenge being fecal analysis that often gives false negatives due to lack of egg shedding at the time of sampling.
That belly! She's doing better know after treatment.
That belly! My puppy is feeling much better now after treatment.

Protozoal Infections

Other common gifts passed from mother to pups (usually those kept in unhygienic conditions) are giardia and coccidian infections.

Giardia is a single-celled organism from the family of organisms that causes amebic dysentery in people. Again, the cysts can persist in a moist environment for many months, making infection common. There are at least 6 species of coccidian that affect dogs, of which Cryptosporidium is the biggest problem in puppies.

One problem with protozoal infections is the risk of reinfection in the same pet — the cysts can cling to fur, ready to be ingested when the pup washes himself.

Bacterial Infections

Did you know that, on average, 1 gram of dog feces contain 23 million fecal coliform bacteria? That’s a lot of bugs, all with the potential to cause stomach cramps, diarrhea and kidney disease.

From salmonella to campylobacter, several bugs can affect puppies.

These can cause debilitating diarrhea with the added risk that they can be passed onto people. Diagnosis of the individual bug and targeted treatment depends on fecal analysis.

Viral Infections

The deadliest virus on our list is parvovirus, with signs occurring 2–5 days after infection, including life-threatening bloody diarrhea and vomiting.

Parvovirus is the Schwarzenegger of the virus world and can survive against all the odds in the environment, with vaccination being essential to maintaining good health.

Distemper can also cause diarrhea amid a host of other symptoms such as coughing, sticky eyes, fever and vomiting.

Less dramatic is coronavirus, which causes diarrhea in pups because of their weak immune systems. But — provided they don’t become dehydrated — it in itself isn’t deadly.

Treatment of Puppy Diarrhea

If you see blood in the stool or your puppy is vomiting, contact your vet immediately.

Diarrhea can be deadly if your pet becomes dehydrated, so it’s important to keep his fluid intake up.

Check the gums to make sure they feel moist — dry-feeling oral membranes are an early sign of dehydration. Syringe in electrolyte solutions to keep hydration steady.

If the puppy is bright in himself, offer a bland diet of white meat with boiled rice or pasta, or a prescription diet designed for upset stomachs.

Straightforward diarrhea should settle within 48 hours, so if the problem persists, seek veterinary advice.

Frequently Asked Questions (FAQ)

What causes vomiting and diarrhea in dogs?

Vomiting and diarrhea in dogs are typically caused by dietary indiscretion, infections, parasites, or underlying health conditions such as inflammatory bowel disease.

How to treat vomiting and diarrhea in dogs?

Treatment for vomiting and diarrhea in dogs typically involves withholding food for 12-24 hours, providing small amounts of water, and then gradually reintroducing a bland diet, along with veterinary care if symptoms persist or worsen.

How long should I wait to take my dog to the vet for diarrhea and vomiting?

You should take your dog to the vet if diarrhea and vomiting persist for more than 24 hours, or immediately if there are additional symptoms such as lethargy, blood in vomit or stool, or inability to keep water down.


  • Small Animal Internal Medicine. Nelson & Couto. Publisher: Mosby. 3rd edition.