Common causes of diarrhea in dogs
Dogs can develop diarrhea for many different reasons. Sometimes, the cause is obvious—like getting into the trash or eating something unusual on a walk. Other times, it’s less clear—like a food allergy that developed over time or a reaction to a new treat.
Vets generally think about diarrhea in two broad categories:
- Primary causes, which start in the digestive tract, and
- Secondary causes, which begin elsewhere in the body.
Determining which type your dog may have can help your vet recommend the most effective treatment.
“Primary” GI causes of diarrhea
These types of problems typically start in the stomach or intestines; they tend to happen when something directly irritates your dog’s digestive system, such as:
- Sudden changes in food
- Eating spoiled food
- Too many treats or table scraps
- Eating non-food items
- Intestinal parasites like worms or Giardia
- Bacterial or viral infections
- Inflammatory bowel disease (IBD)
- Food sensitivities
With primary causes, the problem is happening within the gut itself.
“Secondary” GI causes of diarrhea
These types of GI problems typically start somewhere else in the body. Sometimes, diarrhea is a symptom of another health issue, including:
- Stress or anxiety
- Hormone imbalances (like Addison’s disease)
- Organ problems (like liver or pancreas issues)
- Certain medications (like some kinds of antibiotics)
In these cases, the digestive tract is reacting to something happening elsewhere in the body.
Many cases of diarrhea are short-term. But if symptoms return or don’t resolve, your vet may want to take a closer look. What you see at home can offer helpful clues for them, so you’re doing the right thing paying attention to their habits and behavior. Finding the cause, which usually requires diagnostic tests, helps your vet recommend the right treatment for your dog and can help prevent future flare-ups.
Why does my dog’s diarrhea keep coming back?
Recurring or “flare-up” diarrhea is common and often confusing for pet parents. You may see symptoms or vomiting improve, only to have another episode show up days or weeks later. When diarrhea follows this pattern, it usually means something hasn’t fully resolved, or the cause hasn’t gone away. Below are a few patterns your vet pays attention to.
Stress patterns
Dogs don’t always show stress the way we do. Sometimes it shows up in their digestive system. Boarding, visitors, travel, routine changes, or even excitement can trigger diarrhea a day or two later.
If stress-related digestive episodes happen repeatedly, your vet may want to rule out underlying medical conditions. In rare cases, hormone disorders like Addison’s disease can cause intermittent diarrhea and may flare during times of stress. While uncommon, this condition needs specific treatment beyond managing diarrhea alone.
Diet-linked patterns
Some dogs tolerate their main diet but react to extras, such as rotating treats, flavored medications, table food, or weekend indulgences.
Unresolved underlying causes
If diarrhea repeatedly improves and returns, it may point to an underlying issue, such as an infection, worms, or an undiagnosed chronic digestive condition.
Keeping a simple log of episodes—including dates, diet changes, stressors, and stool consistency—can provide valuable clues for your vet.
When is diarrhea serious? 8 red flags to watch for
While many cases of diarrhea are mild and pass quickly, certain symptoms are a signal that your dog may need medical attention sooner rather than later.
If you notice any of the signs below, it’s best to contact your vet right away. Even if you’re unsure, it’s always okay to check. Your vet can help you decide what next steps make sense.
- Blood in the stool
- Black, tarry stool
- Repeated vomiting
- Refusal to eat
- Lethargy, weakness, or collapse
- Signs of dehydration (dry gums, sunken eyes, excessive panting)
- Not acting like themselves
- Diarrhea lasting more than a day or two
Puppies, senior dogs, and dogs with chronic medical conditions should be seen sooner, since they can become dehydrated more quickly.
How to treat dog diarrhea: What can I safely do at home?
If symptoms seem mild, and you aren’t seeing any red flag signs, your veterinarian may recommend some simple steps at home to help:
- Offer small, frequent meals of a bland diet (such as plain boiled chicken and cooked white rice) for 24 hours.
- Provide plenty of fresh water.
- Avoid treats and table scraps until stools return to normal.
- Monitor frequency, color, and consistency closely.
If your dog doesn’t improve within a day or two, or if symptoms worsen, contact your vet. Don’t withhold food unless your vet recommends it.
These at‑home steps can help if your dog just has an upset stomach. But if the diarrhea doesn’t resolve or keeps coming back, it’s time to loop in your vet. They can run tests to find the underlying cause and help your dog feel better in the long term.
When should I call my vet?
It’s common to wonder if you’re overreacting, but when it comes to digestive issues, it’s always okay to check. Reach out to your vet if:
- Diarrhea lasts more than a day or two.
- Symptoms improve but keep returning.
- Your dog is very young, older, or managing another health condition.
- You notice any red flag symptoms.
- You’re unsure whether the situation is urgent.
You know your dog best. If something feels off, a quick call can help put your mind at ease—and, if necessary, figure out what to do next.
What to expect at the vet
If diarrhea lasts more than a day or two, or keeps coming back, your vet may recommend running some tests to help understand what’s going on. These tools help narrow down the cause more quickly and avoid guesswork.
To look into primary causes of diarrhea, your vet may recommend:
- Stool testing to look for parasites, bacteria, or infections
- A diet trial to see if food sensitivity is the trigger
- Imaging (like X-rays or ultrasounds)
These tests help determine whether the problem is happening inside the digestive tract.
If something stands out during the physical exam or in your dog’s history, your vet may recommend testing to look into secondary GI causes of diarrhea. This includes:
- Blood work to check organ function and hydration
- Tests to look at the pancreas, liver, or hormone levels
These tests help find problems that may be affecting the gut from outside the digestive system.
Helping your dog feel better—and stay better
Dealing with diarrhea can be frustrating, especially when it keeps coming back or doesn’t follow a clear pattern. The good news is that many cases are mild and short‑lived. And when they aren’t, paying attention to changes—like how your dog is acting, eating, and feeling overall—can make a real difference. Those observations help you and your vet decide what next steps make sense.
If something doesn’t feel right, trust that instinct. Reaching out to your vet can help you sort through what you’re seeing and take the guesswork out of what to do next. With the right support, your dog can get back to feeling like themselves.
Frequently asked questions
Frequently asked questions about this topic
Some veterinarians may recommend a bland diet—like plain boiled chicken and rice—for certain dogs with mild diarrhea, but feeding changes should be based on your veterinarian’s guidance. Make sure your dog has plenty of water.
Do not give your dog human medications, which can be unsafe. If symptoms persist or worsen, call your vet.
Some dogs do have sensitive stomachs and may react to small changes, like a new treat or a shift in routine. That said, diarrhea that keeps coming back isn’t something to brush off and is worth discussing with your vet.
Not necessarily; changing foods can sometimes make digestive upset worse. If diarrhea keeps happening, your vet can help you decide whether a diet change makes sense.
Keep a simple log of dates, food changes, stressors, medications, and stool consistency. These details are extremely helpful during a veterinary visit.
f you’re considering plain canned pumpkin, ask your veterinarian whether it’s appropriate for your dog. For some dogs, plain canned pumpkin (not pie filling) is generally safe and may help with mild cases.
To be clear, though, it is not a cure or a substitute for veterinary evaluation. If your dog’s symptoms continue, it’s best to play it safe and check in with your vet.
Yes. Changes in routine, travel, boarding, or even excitement can upset some dogs’ digestive systems. If stress-related diarrhea happens often, your vet may want to make sure there isn’t something else going on.
Mild diarrhea may improve within a day or two, but it can vary. If it lasts longer than that or keeps coming back, it’s a good idea to contact your vet.
