Introduction
Few things worry a dog owner more than finding loose, watery stools where firm ones used to be. Diarrhea is one of the most common problems dogs face, and in many cases it passes quickly with a little care and patience. Most short episodes have a simple explanation, such as a sudden change of food, a stolen snack, a stressful day, or a mild tummy upset. This guide explains the most common possible causes, what you can do at home, the warning signs that mean a vet visit is needed, and how to help prevent it. It is general information only — not a diagnosis — and it does not replace advice from your own vet.
What Is Diarrhea in Dogs?
Diarrhea means stools that are loose, watery, or much more frequent than usual. A healthy dog usually passes firm, well-formed stools once or twice a day. When the digestive system is upset, food and water move through the gut too quickly, or the gut cannot absorb water properly, and the result is soft or liquid stool. A single loose stool after an unusual meal is not always a cause for panic, but diarrhea becomes more of a concern when it happens several times a day, lasts more than a day or two, or comes with vomiting, tiredness, or a loss of appetite.
Common Possible Causes of Diarrhea in Dogs
Diarrhea is a symptom, not a disease on its own. Many things can cause it, and the most likely cause often depends on what has changed in your dog’s life recently.
1. A Sudden Diet Change
This is one of the most common causes. A dog’s gut needs time to adjust to a new food, so switching brands or types overnight — even to a better-quality food — can lead to loose stools for a day or two.
2. Eating Something They Should Not Have
Dogs explore the world with their mouths, and many will eat almost anything they find. Table scraps, fatty leftovers, and rich human food can all trigger diarrhea. Scavenging is another classic cause: a dog that raids the bin or eats food found on a walk may swallow something spoiled or indigestible. If your dog has been sick as well, the two problems often go together — see our guide on why your dog may be throwing up yellow bile.
3. Too Many Treats or a New Treat
Treats are a lovely way to reward your dog, but too many of them — or a brand-new type of treat — can cause trouble. Rich chews and high-fat snacks are common culprits, especially in large amounts.
4. Stress and Excitement
Just like people, dogs can get an upset stomach when they are stressed or over-excited. Moving house, a new baby or pet, fireworks, a thunderstorm, a long car journey, or a stay in kennels can all affect the gut.
5. Parasites
Intestinal parasites, such as worms, are a possible cause, especially in puppies and in dogs that have not had regular worming treatment. Parasites can irritate the gut lining and interfere with digestion. Possible signs include diarrhea that keeps coming back, weight loss despite a normal appetite, or a dull coat.
6. Infections
Bacterial and viral infections can also cause diarrhea. Dogs can pick up infections from contaminated food or water, from other dogs, or from something they eat outdoors. Puppies and older dogs may be more vulnerable. Infections often come with other signs, such as vomiting, fever, tiredness, or a loss of appetite.
7. Food Sensitivities
Some dogs have a sensitive stomach or a food sensitivity that makes certain ingredients hard to digest, such as a particular protein or a sudden increase in fat. Unlike a simple upset stomach, sensitivity-related diarrhea may keep returning whenever the trigger food is eaten.
8. Other Health Problems
Less commonly, ongoing diarrhea can be linked to other health problems, such as inflammation of the gut or problems with the pancreas or liver. These are less likely when the diarrhea is a one-off event, but more likely when the problem keeps returning or does not settle.
How to Help Your Dog at Home
For a mild, short episode in an otherwise healthy adult dog, simple home care is often enough while the gut settles. The aim is to keep your dog hydrated, comfortable, and rested.
Keep Fresh Water Available at All Times
Diarrhea causes your dog to lose water, so fresh, clean water should always be available. Keep the bowl full and easy to reach, and check it more often than usual.
Let the Stomach Rest, Then Offer Bland Food
Once any vomiting has settled, a short period of plain, bland food often helps. A simple mix of plain boiled chicken (no skin, bones, or seasoning) and plain boiled white rice is gentle and easy to digest. Offer small, frequent meals — three or four small portions spread through the day are easier for an upset stomach than one large meal.
Keep Your Dog Comfortable and Rested
A dog with diarrhea may feel tired or a little anxious, so give them a warm, quiet place to rest and keep their routine calm. Avoid long walks and rough play until the stools are back to normal.
Watch Closely for Changes
Keep an eye on your dog over the next 24 to 48 hours. Are the stools slowly getting firmer? Is your dog drinking, eating a little, and still interested in what is going on? Gradual improvement is a good sign. If things are getting worse — more frequent watery stools, vomiting, or your dog becoming quiet and withdrawn — it is time to call the vet.
What NOT to Do
When your dog has diarrhea, it is natural to want to fix it fast. But some well-meaning actions can make things worse.
Do Not Give Human Medicine
Never give your dog medicine meant for people, including anti-diarrhea tablets or painkillers, unless your vet has specifically told you to. Many human medicines are unsafe for dogs, even in small amounts. If you think your dog needs medicine, call your vet first.
Do Not Starve Your Dog for a Long Time
A very short pause in feeding may be appropriate in some cases, but a long fast can do more harm than good, especially for puppies, small dogs, and older dogs.
Do Not Switch Foods Again
It can be tempting to try a different food straight away, hoping it will fix the problem. But another sudden change is likely to upset the stomach even more. Stick with bland food for a short while, then return slowly to the food your dog was eating before, unless your vet advises otherwise.
Do Not Ignore Blood in the Stool
If you see blood in your dog’s stool, do not wait and hope it goes away. Blood can be a sign of something that needs prompt veterinary attention. Our guide on what blood in your dog’s stool could mean and what to do next explains the possible signs to look for and why a vet visit matters.
Do Not Wait Too Long With a Puppy or an Older Dog
Puppies, very old dogs, and dogs that are already unwell can become dehydrated much faster than a healthy adult dog. If any of these dogs develop diarrhea, contact your vet early, even if the diarrhea seems mild.
When to See a Vet
Most mild cases settle within a day or two. But some signs mean your dog needs veterinary care, sometimes urgently. Contact your vet if you notice any of the following:
- Blood in the stool, or black, tarry stools
- Vomiting at the same time as diarrhea
- Diarrhea lasting more than 24 to 48 hours
- Lethargy, weakness, or unusual quietness
- Loss of appetite, or refusing food and water
- Signs of dehydration, such as dry gums or sunken eyes
- A swollen or painful belly, fever, shaking, or signs of pain
- Your dog is very young, very old, or already has a health condition
- You suspect poisoning or a swallowed object
If your dog has swallowed something they should not have, do not wait to see if it passes — call your vet or an emergency vet straight away. When you call, have a few details ready: when the diarrhea started, how often it is happening, what your dog has eaten, whether there is vomiting, and whether your dog is still drinking. If you need a new vet, our guide on how to choose a vet for your pet may help.
How to Help Prevent Diarrhea in the Future
You cannot prevent every episode — dogs will always find something interesting on a walk — but a few simple habits can greatly reduce the risk.
Change Foods Slowly
Change your dog’s food gradually over about a week. Start by mixing a small amount of the new food into the old food, then slowly increase the new food day by day. A slow transition gives the gut time to adjust and is one of the easiest ways to avoid an upset stomach.
Keep Bins and Food Secure
Use bins with secure lids, keep food out of reach on counters, and do not leave bags of dog food or treats where your dog can tear into them.
Go Easy on Table Scraps and Treats
Avoid table scraps, especially fatty or rich foods, spicy foods, and anything with bones. Keep treats to a small part of the daily diet, and introduce any new treat in a small amount first to see how your dog’s stomach handles it.
Keep Worming and Vaccinations Up to Date
Follow your vet’s advice on worming and vaccinations. Regular preventive care helps protect your dog against parasites and infections that can cause diarrhea. If you are not sure when your dog is next due, your vet’s practice can check the records for you.
Keep a Routine
Dogs feel safest with a regular routine. Regular meal times, regular walks, and a calm home help reduce stress-related stomach upsets.
Frequently Asked Questions
How long does dog diarrhea usually last?
Mild diarrhea often settles within 24 to 48 hours with simple home care, such as fresh water, rest, and a short period of bland food.
What should I feed my dog with diarrhea?
Once any vomiting has settled, plain boiled chicken and plain boiled white rice in small, frequent meals is a gentle option for a short period. Keep everything plain, with no seasoning, oil, or butter. After a day or two, slowly mix your dog’s normal food back in.
Is it normal for my dog to have diarrhea after changing food?
Yes, it can be very common, especially if the food was changed suddenly. A dog’s gut needs time to adjust to new food. Change foods slowly over about a week, mixing the new food into the old food a little more each day.
Should I worry if my dog has diarrhea but seems fine otherwise?
If your dog is still bright, drinking, eating a little, and acting like themselves, a short episode may settle on its own.
When is diarrhea an emergency?
Seek veterinary help urgently if there is blood in the stool, if the stool is black and tarry, if your dog is vomiting as well, if they are very lethargic or weak, if they show signs of dehydration, or if you suspect poisoning or a swallowed object. Puppies, very old dogs, and dogs with existing health problems should also be seen sooner rather than later.
Conclusion
Diarrhea is messy, worrying, and very common — but in most cases it is also short-lived. A sudden change of food, a stolen snack, a stressful day, or a mild stomach upset can all cause loose stools that settle within a day or two with fresh water, rest, and a little bland food. The key is to watch your dog closely and know the warning signs: blood in the stool, vomiting at the same time, diarrhea lasting more than a couple of days, tiredness, or a loss of appetite all mean it is time to call the vet. Trust your instincts — you know your dog better than anyone.