Dog Diarrhea: How To Identify, Diagnose, and Treat It

If your dog has diarrhea, you’re not alone—digestive upset is one of the most common health issues pet parents face. While an occasional loose stool isn’t usually a cause for concern, persistent or severe diarrhea can signal an underlying problem that requires attention.

Diarrhea in dogs can result from various causes, including diet changes, infections, parasites, stress, or underlying medical conditions. It’s essential to understand what’s normal, what’s not, and when to seek veterinary care.

A dog’s digestive health is closely linked to their diet. Low-quality dog foods often contain fillers, artificial additives, and hard-to-digest ingredients that can lead to chronic digestive problems. On the other hand, feeding a high-quality, fresh diet like Ollie can support gut health, improve nutrient absorption, and help prevent recurring diarrhea.

In this guide, we’ll cover everything you need to know about dog diarrhea—from identifying the different types and causes to treatment options and prevention strategies. Whether your dog has a one-time upset stomach or frequent digestive issues, this article will help you understand how to keep their gut healthy and their stools solid.

Key Takeaways

• Dog diarrhea is common and can be caused by diet changes, infections, parasites, or stress.
• Mild cases may resolve at home, but persistent or severe diarrhea requires a vet visit.
• A high-quality diet like Ollie supports digestive health, while low-quality foods with fillers can contribute to stomach issues.

What Is Diarrhea in Dogs?

Diarrhea in dogs refers to loose, watery, or frequent stools and is a symptom of an underlying issue rather than a disease itself. It can range from a single episode of soft stool to ongoing, chronic digestive distress.

Acute vs. Chronic Diarrhea

• Acute diarrhea comes on suddenly and usually lasts a day or two. It’s often caused by dietary indiscretion (eating something they shouldn’t), a sudden food change, mild infections, or stress. Most cases resolve on their own with proper care.
• Chronic diarrhea lasts for weeks or recurs frequently. It may signal food intolerances, inflammatory bowel disease (IBD), or a more serious health issue that requires veterinary attention.

Why Diarrhea Matters

While occasional soft stools aren’t uncommon, frequent or severe diarrhea can cause dehydration, nutrient loss, and digestive imbalance. Small dogs and puppies are especially vulnerable, as they can dehydrate quickly.

Because diarrhea is often linked to diet and gut health, feeding high-quality, fresh dog food can promote healthy digestion and reduce the risk of chronic stomach issues.

Common Causes of Diarrhea in Dogs

There are many potential reasons why your dog has diarrhea, ranging from minor digestive upset to more serious medical conditions. Identifying the cause can help determine whether your dog’s diarrhea will pass on its own or if veterinary care is needed.

1. Dietary Indiscretion (“Garbage Gut”)

Dogs are curious eaters and often consume things they shouldn’t—table scraps, spoiled food, or even non-food objects. This can irritate the digestive system and cause sudden, watery diarrhea.

• Signs to watch for: Vomiting, bloating, discomfort, or signs of poisoning if toxic foods were consumed.

2. Sudden Diet Changes

Switching your dog’s food too quickly can disrupt their gut microbiome, leading to diarrhea. A proper transition over 7-10 days helps prevent digestive upset.

• Tip: When transitioning to a fresh, high-quality diet, mix small amounts with their old food and gradually increase over time.

3. Food Intolerances or Allergies

Some dogs react poorly to common allergens like chicken, beef, dairy, wheat, or soy. These sensitivities can lead to chronic diarrhea, itching, and ear infections.

• Solution: A limited-ingredient, highly digestible diet can help pinpoint and eliminate food triggers.

4. Parasites (Worms, Giardia, Coccidia)

Internal parasites, especially in puppies and dogs that spend time outdoors, can cause persistent, foul-smelling diarrhea. Common culprits include:

• Roundworms & Hookworms (often seen in puppies)
• Giardia & Coccidia (common in shelter or rescue dogs)
• Warning signs: Mucus in stool, weight loss, bloating, or lethargy. A vet can confirm parasites through a fecal test.

5. Bacterial & Viral Infections

Bacteria like Salmonella and E. coli or viruses like parvovirus can cause severe diarrhea, especially in young or unvaccinated dogs.

• Emergency signs: Bloody diarrhea, fever, vomiting, and extreme lethargy. Seek immediate veterinary care.

6. Toxins & Poisonous Substances

Dogs may ingest toxic plants, human medications, or chemicals, leading to vomiting, diarrhea, and life-threatening symptoms.

If you suspect poisoning: Call your vet or the ASPCA Poison Control Hotline (888-426-4435) immediately.

7. Stress or Anxiety

Just like humans, dogs can experience stress-related diarrhea due to anxiety, changes in routine, travel, or boarding.

• Prevention: Provide a stable routine, calming supplements, and a diet rich in gut-friendly nutrients.

8. Underlying Health Conditions

Chronic diarrhea can be a sign of deeper health issues like:

• Inflammatory Bowel Disease (IBD)
• Pancreatitis (inflammation of the pancreas)
• Liver or Kidney Disease

What to do: If diarrhea persists for more than a few weeks, consult your vet for diagnostic testing.

9. Medication Side Effects

Some antibiotics, NSAIDs, or dewormers can disrupt gut bacteria and cause temporary diarrhea.

• Solution: Pair medications with probiotics or digestive-supporting foods to maintain a healthy gut.

Types of Dog Diarrhea & What They Mean

The appearance of your dog’s diarrhea can provide important clues about the underlying cause. While any persistent or severe diarrhea should be evaluated by a vet, knowing what different types of stool indicate can help you determine the best course of action.

1. Watery Diarrhea (Severe, Liquid Stool)

Often caused by bacterial or viral infections, parasites, food intolerance, or stress. It can also indicate a more serious condition like hemorrhagic gastroenteritis (HGE).

When to worry: If it lasts more than 24 hours, leads to dehydration, or contains blood, seek veterinary care immediately.

2. Mucus in Stool (Slimy, Gel-like Coating)

Mucus in your dog’s poop often signals colitis (inflammation of the colon), which can be triggered by stress, infections, parasites, or dietary changes.

When to worry: If mucus persists for more than a few days or is accompanied by other symptoms like vomiting or lethargy.

3. Bloody Diarrhea (Red or Black Stools)

Bright red blood (hematochezia) may indicate colitis, parasites, or a rectal injury, while black, tarry stool (melena) suggests bleeding in the stomach or intestines. Both require urgent veterinary attention.

Emergency: Blood in stool can be a sign of poisoning, parvovirus, or hemorrhagic gastroenteritis—contact your vet immediately.

4. Soft, Unformed Stools (Mushy but Not Liquid)

This is one of the most common signs of dietary issues, including food intolerances or a sudden diet change. It may also indicate mild stress-related diarrhea.

Prevention: Transition foods gradually and ensure your dog is on a high-quality, digestible diet, which avoids hard-to-digest fillers that can lead to chronic soft stools.

Try Ollie: Ollie dog food has been shown to help dogs improve digestion by providing firmer, more solid stools, which support overall digestive health.

5. Yellow Diarrhea

Yellow stool can result from rapid food passage through the digestive system, bile imbalance, or liver issues. It can also be a sign of Giardia, a common parasite.

When to worry: If yellow diarrhea is frequent or paired with weight loss, weakness, or vomiting, a vet visit is needed.

6. Green Diarrhea

Green stool can be caused by eating a large amount of grass, but it can also indicate a bacterial infection or gallbladder/liver dysfunction.

When to worry: If your dog hasn’t eaten grass and the stool remains green for more than a day.

7. Chronic, Recurring Diarrhea

If diarrhea comes and goes over several weeks, it may be linked to food allergies, inflammatory bowel disease (IBD), or another chronic health issue.

Prevention: A limited-ingredient, high-quality diet can help manage food sensitivities and improve long-term gut health.

The color and texture of your dog’s diarrhea can provide valuable clues about their health. While mild cases can often be managed with dietary adjustments and hydration, prolonged or severe diarrhea requires veterinary attention.

Symptoms That Require Veterinary Attention

While mild cases of diarrhea often resolve on their own, some symptoms indicate a more serious issue requiring immediate veterinary care. If your dog has diarrhea along with any of the following symptoms, it’s best to contact your vet.

1. Diarrhea Lasting More Than 24-48 Hours

If diarrhea persists for more than a day or two, it may lead to dehydration and indicate an underlying health problem. Chronic diarrhea (lasting more than two weeks) often signals food sensitivities, parasites, or a medical condition like IBD or pancreatitis.

Next steps: Ensure your dog stays hydrated and schedule a vet visit if diarrhea continues or worsens.

2. Blood in Stool (Red or Black Diarrhea)

Bright red blood (hematochezia) suggests issues like colitis, parasites, or an anal gland problem, while black, tarry stool (melena) indicates bleeding in the upper digestive tract—both require urgent veterinary care.

Emergency: Contact your vet immediately if you see significant blood, especially if paired with vomiting or lethargy.

3. Lethargy, Weakness, or Collapse

If your dog is extremely tired, weak, or unresponsive, this could be a sign of dehydration, infection, toxin exposure, or a more serious illness.

Emergency: Severe lethargy combined with diarrhea may indicate a life-threatening condition like parvovirus or hemorrhagic gastroenteritis (HGE)—seek immediate vet care.

4. Vomiting Along With Diarrhea

Occasional vomiting and diarrhea may result from mild indigestion, but frequent vomiting and watery diarrhea together can quickly lead to dehydration and electrolyte imbalances.

Next steps: If your dog vomits multiple times in a day or cannot keep food/water down, call your vet.

5. Signs of Dehydration

Diarrhea causes fluid loss, which can quickly dehydrate your dog, especially puppies and small breeds.

Warning signs of dehydration:

• Dry, sticky gums
• Sunken eyes
• Loss of skin elasticity (pinch the skin on the back—if it stays tented, your dog is dehydrated)

Next steps: Encourage drinking fresh water or offer an electrolyte solution. If dehydration is severe, IV fluids from a vet may be needed.

6. Straining, Pain, or Unusual Stool Smell

If your dog is straining but only passing small amounts of diarrhea, they may have colitis or an intestinal blockage. A foul, rotten odor could indicate an infection or internal bleeding.

Next steps: If diarrhea is painful, foul-smelling, or your dog struggles to go, see a vet ASAP.

7. Puppy Diarrhea (Higher Risk of Complications)

Puppies dehydrate faster than adult dogs and are more vulnerable to parasites, infections, and parvovirus. Even mild diarrhea in a puppy should be closely monitored.

Next steps: If your puppy has diarrhea for more than 12 hours, call your vet to rule out serious issues.

Diagnosing the Cause of Dog Diarrhea

If your dog has persistent or severe diarrhea, a veterinarian will perform a thorough evaluation to pinpoint the cause. Diagnosis typically involves a combination of history-taking, physical exams, and diagnostic tests.

1. Questions Your Vet Will Ask

To narrow down potential causes, your vet may ask:

• How long has the diarrhea lasted?
• Is there blood, mucus, or an unusual color in the stool?
• Has your dog recently changed diets or eaten something unusual?
• Are there other symptoms (vomiting, lethargy, fever, weight loss)?
• Is your dog on any medications?
• Has your dog been exposed to new environments, other animals, or possible toxins?

Keeping a log of symptoms, stool appearance, and dietary changes can help provide clearer answers.

2. Physical Examination

Your vet will check for signs of dehydration, pain, bloating, fever, or abnormal weight loss, which could indicate a more serious underlying condition.

3. Common Diagnostic Tests

Depending on the symptoms, your vet may recommend:

• Fecal Exam: Checks for parasites, bacteria, or abnormal gut flora.
• Blood Tests: Identifies infections, organ dysfunction, or inflammatory conditions.
• X-rays or Ultrasound: Detects foreign objects, tumors, or structural issues in the digestive tract.
• Dietary Elimination Trials: Rules out food allergies by testing different diets.

4. The Role of Diet in Diagnosis

If no immediate illness is found, poor diet quality is often a contributing factor to chronic diarrhea. Many commercial dog foods contain fillers, artificial additives, and hard-to-digest ingredients that disrupt gut health. Many pet parents find that switching to a fresh dog food diet can help to alleviate digestive issues.

Dog Diarrhea Treatments

The right treatment for dog diarrhea depends on its cause and severity. While mild cases can often be managed at home, more serious diarrhea may require veterinary care. Below are the most effective treatments based on the situation.

1. At-Home Remedies for Mild Diarrhea

If your dog is otherwise healthy and acting normal, you can try these home treatments for mild, short-term diarrhea:

Temporary Fasting (12–24 Hours)

Giving your dog’s digestive system a brief rest can help clear up simple cases of diarrhea. Provide plenty of fresh water to prevent dehydration.

Bland Diet (Boiled Chicken & Rice)

A plain diet of boiled chicken (no seasoning) and white rice can help firm up stools. Feed small portions and gradually reintroduce regular food over 2–3 days.

Pumpkin & Probiotics

• Plain canned pumpkin (not pie filling) is rich in fiber and can help regulate digestion.
• Dog-safe probiotics restore healthy gut bacteria and improve stool consistency.

Hydration & Electrolytes

Encourage drinking by offering fresh, clean water or adding low-sodium bone broth. Dogs losing a lot of fluids may benefit from an electrolyte supplement.

2. When Veterinary Treatment is Needed

If your dog has severe, prolonged, or bloody diarrhea, a vet may recommend:

Prescription Medications

• Anti-diarrheal meds (like metronidazole or tylosin) to reduce intestinal inflammation.
• Antibiotics if a bacterial infection is present.
• Dewormers if parasites are the cause.

IV Fluids for Dehydration

Severe diarrhea can quickly lead to dangerous dehydration, especially in puppies or small breeds. IV fluids restore hydration and electrolyte balance.

Prescription Diets

For dogs with chronic digestive issues, a vet may recommend a prescription gastrointestinal diet—but for long-term digestive health, a high-quality, natural diet can be a better option to support gut health naturally.

3. Transitioning Back to Regular Food

Once diarrhea improves, transition back to regular food gradually over 3–5 days to avoid further stomach upset.

Preventing Dog Diarrhea

While some cases of diarrhea are unavoidable, many can be prevented by maintaining a healthy diet, reducing exposure to harmful substances, and supporting gut health. Here’s how to help keep your dog’s digestion on track:

1. Feed a High-Quality, Consistent Diet

One of the biggest contributors to digestive upset is low-quality food filled with artificial additives, fillers, and hard-to-digest ingredients. Many commercial kibbles contain by-products and cheap grains that can irritate your dog’s stomach.

A human-grade, highly digestible diet like Ollie can help prevent diarrhea by providing natural, nutrient-rich ingredients that support gut health and regular, firm stools.

2. Transition Foods Slowly

If switching your dog’s food, do so gradually over 7–10 days to allow their digestive system to adjust. Sudden diet changes are a common cause of diarrhea.

3. Avoid Table Scraps & Toxic Foods

Many human foods, such as fatty meats, dairy, chocolate, onions, and artificial sweeteners (xylitol), can trigger diarrhea or toxicity. Stick to dog-friendly treats and meals.

4. Keep Your Dog Hydrated

Dehydration worsens digestive issues. Ensure fresh, clean water is always available, especially during hot weather or after exercise.

5. Protect Against Parasites & Infections

• Regular Deworming & Preventatives – Internal parasites like Giardia and roundworms are common causes of diarrhea. Keep up with deworming and flea/tick prevention.
• Vaccinations – Protect against viruses like parvovirus that can cause severe, bloody diarrhea.
• Avoid Stagnant Water & Unfamiliar Feces – Drinking from puddles or eating contaminated material increases infection risks.

6. Reduce Stress & Anxiety

Dogs can develop diarrhea due to stress from travel, new environments, loud noises, or separation anxiety. Help them feel secure with:

• A consistent routine
• Reduction of environmental stress
• Calming supplements (if needed)
• A nutritious diet that supports overall well-being

Frequently Asked Questions About Dog Diarrhea

1. When should I worry about my dog’s diarrhea?

Mild diarrhea that lasts less than 24 hours is usually not a major concern, especially if your dog is otherwise acting normal. However, if diarrhea lasts more than 48 hours, contains blood (either red or black), or is accompanied by vomiting, fever, lethargy, or dehydration, it’s important to seek veterinary care. Prolonged diarrhea can lead to dehydration and nutrient loss, which can be especially dangerous for puppies, senior dogs, and small breeds.

2. What should I feed my dog if they have diarrhea?

For mild diarrhea, feeding a bland diet of boiled chicken and plain white rice in small portions can help soothe the stomach. Plain canned pumpkin is also beneficial because it contains fiber that can firm up stools. Adding a probiotic supplement or feeding a fresh, highly digestible diet can also support gut health. If diarrhea persists beyond a couple of days, or if your dog refuses food, consult a vet for further guidance.

3. Can I give my dog over-the-counter medication for diarrhea?

Some human medications, like Pepto-Bismol or Imodium, are sometimes used for dogs with diarrhea, but they are not safe for all breeds and can cause adverse reactions. It’s always best to check with your veterinarian before giving your dog any over-the-counter medication. Some medications can mask symptoms of a more serious issue, so professional guidance is recommended before administering any treatment.

4. Can stress cause diarrhea in dogs?

Yes, stress and anxiety can contribute to diarrhea in dogs. Major changes, such as moving to a new home, traveling, boarding, or introducing a new pet, can trigger digestive upset. Stress-related diarrhea is often temporary and resolves once the dog adjusts to their environment. Ensuring a stable routine, providing calming supplements, and feeding a gut-friendly diet can help minimize stress-induced stomach issues.

5. How can I prevent my dog from getting diarrhea?

Preventing diarrhea starts with feeding a consistent, high-quality diet that is free from fillers and artificial additives. Sudden food changes should be avoided, as they can disrupt the digestive system. Keeping your dog away from table scraps, garbage, and toxic foods is also essential. Regular vet visits, vaccinations, and deworming treatments can help prevent infections that cause diarrhea. Ensuring your dog stays hydrated and managing stress levels can also contribute to better digestive health.

6. Does my dog’s diet affect their poop consistency?

Yes, a dog’s diet has a significant impact on stool consistency. Low-quality dog foods with artificial additives, fillers, and poor-quality proteins can lead to chronic loose stools or digestive issues. On the other hand, feeding a fresh, nutrient-rich diet like Ollie can improve digestion, support gut health, and promote firmer stools. A well-balanced diet that includes high-quality protein, fiber, and healthy fats is key to maintaining optimal stool consistency.