Why Does My Dog Have Diarrhea? Common Causes and What to Do

When your dog has diarrhea, it's certainly an unpleasant experience. It is also one of the most common reasons dogs end up at the vet, but most cases are mild and generally improve after a day or two. But if your dog's diarrhea worsens, it could indicate a more critical health issue.

Your dog's upset stomach becomes a very serious concern when they refuse food and water, are lethargic, and drop body weight. In puppies, non-stop diarrhea can quickly lead to dehydration and requires immediate veterinary attention.

Once you are aware of the warning signs, you can implement the right treatment plan to help your pup feel like themselves again. We look at acute and chronic diarrhea, causes of a runny tummy, homecare tips for mild diarrhea, and when your pet's condition is an emergency.

Key Takeaways

• Acute diarrhea usually occurs when dogs eat something they shouldn't and resolves in a day or two.
• Should you notice blood in the stool, constant vomiting, fever, and a lack of energy, it is time to call the vet.
• Older dogs and young puppies suffering from diarrhea are at higher risk of dehydration and must have access to fresh water at all times.
• Dogs with mild diarrhea can benefit from a bland diet and gut support by applying a probiotic to their food.

What are the Most Common Causes of Diarrhea in Dogs?

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Diarrhea in dogs is a symptom of an underlying cause, whether that be a food intolerance or a viral infection. For example, most dogs will experience acute diarrhea after eating garbage, while other dogs with food sensitivities suffer from chronic or recurring diarrhea.

Understanding the most common causes of diarrhea in dogs can help you differentiate between mild stomach irritation and medical emergencies.

Food Intolerance

A food intolerance is described as an unusual physiological reaction to a specific food or additive (Craig, 2018). This means that dogs suffering from food allergies experience symptoms such as diarrhea, itchy skin, vomiting, and gastrointestinal discomfort after consuming the food.

Ingesting table scraps and spoiled food irritates the gut, resulting in loose stools. Fatty treats and large amounts of dairy make diarrhea worse and should be avoided (Grandi et al., 2018). 

If you suspect that your dog has a food allergy, you can place them on a food trial or an elimination diet. According to Lam et al. (2019), food trials are considered the gold standard for identifying adverse food reactions (AFR) in dogs.

The elimination diet requires replacing common allergens, such as chicken and beef, with novel proteins, like venison or duck. It can take several weeks, but your dog's symptoms should subside once the allergy-causing food is removed. Slowly reintroduce your dog's regular food. If the diarrhea and itchy skin return, the original food allergen is responsible for the irritation.

Sudden Dietary Changes

Sudden food changes will upset your dog's stomach. Research shows that your dog's microbiome takes up to 10 days to adjust to a different food brand (Lin et al., 2022). Change to a new recipe over a week or so to reduce the risk of your dog developing diarrhea.

Ongoing Stress and Anxiety

Dogs suffer from acute diarrhea when they become anxious or stressed. This is known as stress colitis. Events such as a thunderstorm, a move, or staying at a boarding kennel can lead to loose stools with streaks of mucus. It is a temporary condition that clears after a few days.

Inflammatory Bowel Disease (IBD) is often confused with stress colitis; however, IBD in dogs is a chronic condition that causes constant diarrhea, vomiting, and weight loss (Cerquetella, 2010).

Parasites and Infections

Internal parasites such as Giardia, hookworm, and whipworm will cause watery diarrhea in dogs and puppies. In cases of severe infestations, your dog may develop diarrhea with blood in it accompanied by increased hunger, weight loss, vomiting, and a pot-belly appearance. Veterinarians perform fecal exams, including microscopic smears, to test for Giardia and worms.

Bacterial or viral infections can also result in diarrhea, including fever and throwing up. Dogs and puppies that have not been fully vaccinated are at risk of contracting canine parvovirus (parvo). It is a life-threatening disease that leads to bloody diarrhea and vomiting.

If your unvaccinated pup's diarrhea worsens and includes other symptoms like vomiting and severe lethargy, seek veterinary care immediately. Puppies diagnosed with parvo require fluid therapy to prevent dehydration.

Eating Something They Shouldn't Have

Many dogs end up at the vet with a runny tummy because they've eaten food such as grapes, chocolates, peanuts, and garlic. These foods, along with xylitol, will cause digestive distress because they are toxic to dogs. You can read our guide on the foods dogs should never eat to avoid unexpected health complications.

Underlying Health Problems

Recurring diarrhea is a cause for concern because it may be a sign of chronic illnesses, including pancreatitis, liver or kidney disease, and low blood sugar (hypoglycemia). In such instances, gastrointestinal upset shows up with other symptoms. Kidney disease presents with common symptoms like constant thirst and frequent urination, whereas low blood sugar is associated with shaking and weakness. 

When is Diarrhea in Dogs a Medical Emergency?

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When your dog has mild diarrhea, it usually resolves on its own over a day or two. But when it is persistent, contains blood, and is coupled with symptoms such as vomiting and lethargy, it is a medical emergency.

If you notice any of the following symptoms, call your vet immediately:

Blood in the Stool

Black and tarry stool, known as melena, is a sign of internal bleeding in dogs (Boysen, 2015). Bloody diarrhea may be caused by ingesting poisons, viral infections, or parasitic infestations.

Vomiting and Weakness

Dogs that experience a single bout of vomiting with diarrhea should be monitored. Some dogs will return to a normal appetite and drinking after a day of illness, but if symptoms progress and include lethargy, it is best to speak to your vet. 

Constant diarrhea accompanied by vomiting and weakness is a medical emergency. Severe vomiting and stomach upset increase your pup’s risk of dehydration. If your dog is refusing to drink water, has extremely low energy, dry gums, and belly aches, they must receive immediate veterinary care. 

Dehydration

Sticky gums, low energy, and skin that does not spring back when pinched are signs of dehydration that call for an emergency vet visit.

Ongoing Diarrhea

When your dog's upset stomach lasts longer than 48 hours or keeps coming back, the underlying cause must be determined by a veterinarian.

Foreign Object Consumption

Dogs that consume foreign objects, such as socks, small toys, bedding, and even underwear, can suffer from intestinal blockages. They will have blood in their stool or strain to defecate, but they do not always present with diarrhea. 

An internal obstruction can cause persistent vomiting, and your dog will lose interest in food and water. This situation becomes a medical emergency when your pup's tummy feels hard and is painful to the touch, and they cannot keep food or water down.

Acting quickly can make all the difference when your pup faces an emergency.

How to Treat Your Dog's Mild Diarrhea at Home

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Pets with a mild bout of diarrhea that are otherwise bright, alert, eating, and drinking can benefit from these treatment tips:

• Always provide access to fresh water to prevent dehydration. If your dog refuses to drink water, it is time to see the vet.
• Withhold food for 12 to 24 hours for adult dogs with mild, uncomplicated stomach upset. This gives the digestive system time to rest.
• You can prepare boiled chicken and plain cooked white rice to soothe sensitive stomachs. Most dogs tolerate chicken quite well because it is easy on the digestive system.
• It is a myth that you should feed your dog pumpkin pie filling when they are ill, as it contains high levels of fat, sugar, and spices like cloves, which are harmful to them. Instead, replace the pie filling with pumpkin puree. Pumpkin's high fiber content helps bind loose stool and is an excellent source of nutrients for compromised immune systems.
• Do not use human medications like Imodium or Pepto-Bismol to treat diarrhea in pets, as it can lead to further health complications.
• Monitor your pet's condition and stools. Report changes, such as watery diarrhea and bloody streaks in the stool, to your vet.

These tips do not constitute medical advice, and you should always consult a veterinarian for a tailored treatment plan.

Support Your Dog's Gut With Probiotics

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Moderate diarrhea in dogs disrupts the gut microbiome, affecting nutrient absorption and healthy bowel movements. Yang and Wu (2023) state that probiotics can reduce inflammation, strengthen immunity, and relieve intestinal conditions in dogs.

Pet owners can help their dog's stomach by adding probiotics, such as our K9 Belly Bliss, to their meals. This daily probiotic supports firmer stools and a healthy microbiome.

You can browse through our range of probiotic supplements for dogs to find the right solution for your pet. While probiotics improve digestive health, they are not a treatment for sick pets. Seek veterinary care if your dog's symptoms deteriorate.

FAQs

What Can I Give My Dog for Diarrhea?

Dogs affected by mild bouts of diarrhea but who are healthy overall can benefit from a very bland diet of boiled chicken and white rice. You can give your dog pureed pumpkin to bind loose stool and probiotics to restore good gut bacteria.

How Long Does Diarrhea Last in Dogs?

Diarrhea should not last longer than 48 hours. In the case of puppies and senior dogs, who are more susceptible to dehydration, do not wait more than 24 hours before contacting your vet.

Is It Safe to Give My Dog Human Medication for Diarrhea?

No, it is not safe to give your dog human medication for digestive upset. Medication for people contains ingredients that are generally toxic for dogs. Speak to your veterinarian for safe treatments.

Conclusion

To effectively manage acute or recurring diarrhea in your pet, the underlying cause must be determined. Whether bacterial infections or ingesting spoiled food, most dogs experience mild bouts of diarrhea, but if it worsens, medical care must be sought.

Stomach upset accompanied by lethargy, vomiting, bloody stools, and weight loss requires further investigation to prevent health complications and life-threatening circumstances.

Many human medications cause toxicity in pets, so we recommend contacting your veterinarian for professional advice.

Pet parents can support their pup's health and GI tract by feeding bland and nutritious foods, such as chicken and pure pumpkin. These gentle foods, along with probiotics, facilitate healthy digestion and can make your pup's tummy feel better.

References

• Craig, J. M. (2018). Food intolerance in dogs and cats. Journal of Small Animal Practice, 60(2).
• Lam, A. T. H., Johnson, L. N., & Heinze, C. R. (2019). Assessment of the clinical accuracy of serum and saliva assays for identification of adverse food reaction in dogs without clinical signs of disease. Journal of the American Veterinary Medical Association, 255(7), 812–816.
• Lin, C.-Y., Jha, A. R., Oba, P. M., Yotis, S. M., Shmalberg, J., Honaker, R. W., & Swanson, K. S. (2022). Longitudinal fecal microbiome and metabolite data demonstrate rapid shifts and subsequent stabilization after an abrupt dietary change in healthy adult dogs. Animal Microbiome, 4(1).
• Cerquetella, M. (2010). Inflammatory bowel disease in the dog: Differences and similarities with humans. World Journal of Gastroenterology, 16(9), 1050.
• Boysen, S. R. (2015). Gastrointestinal hemorrhage. Small Animal Critical Care Medicine, 630–634.
• Grandi, M., Pinna, C., Bonaldo, A., Stefanelli, C., Vecchiato, C. G., Zaghini, G., & Biagi, G. (2018). Effects of dietary supplementation with increasing doses of lactose on faecal bacterial populations and metabolites and apparent total tract digestibility in adult dogs. Italian Journal of Animal Science, 17(4), 1021–1029.
• Yang, Q., & Wu, Z. (2023). Gut probiotics and health of dogs and cats: Benefits, applications, and underlying mechanisms. Microorganisms, 11(10), 2452–2452.