Article • Designer Mixes

Dog Has the Runs: What to Do at Any Age

Shari Shidate Designer Mixes contributor

Few things worry dog parents faster than sudden diarrhea. One minute your pup is fine, and the next you are rushing outside at 2 a.m., wondering if this is a simple stomach upset or something more serious. The good news is that many cases are mild. The important part is knowing what to watch, what you can safely do at home, and when it is time to call your vet.

As a veterinary assistant in Frisco, Texas, I have seen the whole range: from a dog who ate a greasy burger wrapper to puppies with parasites, to seniors who needed urgent care. This guide walks you through practical, conservative steps for dogs of every age.

First: is it diarrhea, or an emergency?

Diarrhea means stools are looser than normal, more frequent, or urgent. It can range from soft-serve to watery. Many mild, uncomplicated cases often improve within 24 to 48 hours. “Uncomplicated” usually means your dog is bright and alert, still drinking, has no blood in the stool, and has little to no vomiting.

Call your veterinarian urgently or go to an emergency clinic if you see:

Blood in the stool (bright red) or black, tarry stool
Repeated vomiting, or your dog cannot keep water down
Severe lethargy, collapse, weakness, or pale gums
Bloated belly, repeated unproductive retching, or obvious abdominal pain
Possible dehydration (tacky gums, very low energy, reduced urination). At-home checks like skin tenting can be less reliable in older or overweight dogs, so treat these as rough clues, not a diagnosis.
Suspected toxin exposure (xylitol, grapes and raisins, rodent bait, medications, THC products, antifreeze)
Possible foreign body (toy, sock, corn cob, bone fragments), especially if there is vomiting, pain, or no stool passing
Profuse watery diarrhea (especially if it is frequent or your dog seems weak). Sudden bloody, watery diarrhea can be a sign of acute hemorrhagic diarrhea syndrome (AHDS) and needs prompt care.
Multiple pets sick in the home (possible toxin or contagious cause)
Puppies, very small dogs, or seniors with watery diarrhea for more than a few hours
Known chronic illness (kidney disease, diabetes, Addison’s disease, cancer) and new diarrhea

If you are unsure, it is always okay to call your vet. A quick phone triage can save you a lot of worry.

Common causes (and why age matters)

Diarrhea is a symptom, not a diagnosis. Here are the most common reasons I see in clinics and shelters, with age-related clues.

Puppies

Parasites (roundworms, hookworms, whipworms, Giardia, coccidia)
Diet changes and new treats during training
Viral illness (parvo is a major concern for unvaccinated puppies)
Stress from a new home, crate training, or new environments

Adult dogs

Dietary indiscretion (trash, fatty foods, table scraps)
Food sensitivity or intolerance
Stress colitis (often mucus, urgent frequent trips, sometimes a little bright red blood)
Parasites or Giardia
Gut imbalance (dysbiosis) after stress, a diet change, or antibiotics
Medication side effects, especially antibiotics or NSAIDs

Senior dogs

Underlying disease (pancreatitis, liver disease, kidney disease, endocrine disorders)
Tumors or inflammatory bowel disease
Less resilience to dehydration and electrolyte changes

What to do in the first 12 to 24 hours

If your dog is bright, alert, drinking, and the diarrhea is mild with no blood, you can often start with supportive care at home. Your goal is simple: support hydration, rest the gut, and reintroduce gentle food.

1) Check hydration

Gums should feel slick, not tacky.
Water intake should be normal or only slightly reduced.
Urination should still happen.

If your dog is not drinking, seems very tired, or you are worried about dehydration, call your vet.

2) Pause the extras

Stop treats, chews, table scraps, rich toppers, and new supplements. Many cases improve just by removing the “extra credit” foods.

3) Food: rest or small meals?

For healthy adult dogs, some vets may recommend a short rest from food (often 8 to 12 hours) for uncomplicated diarrhea. Other vets prefer skipping the fast and offering small bland meals right away. Either approach can be reasonable in mild cases, but follow your veterinarian’s guidance, especially if your dog has any medical history.

Fasting is not appropriate for:

Puppies
Toy breeds prone to low blood sugar
Diabetic dogs
Dogs with other medical conditions

When in doubt, skip fasting and move straight to small, bland meals.

4) Offer water strategically

Let your dog drink, but if they are gulping and then vomiting, offer smaller amounts more often. For example, you might offer a few tablespoons every 10 to 15 minutes for a small dog, or a quarter cup at a time for a medium to large dog. If vomiting continues, do not force fluids and call your vet.

Bland diet basics

Bland diets work because they are easy to digest and low in fat. Fatty meals can worsen diarrhea, especially if pancreatitis is involved.

Simple bland meal options

Boiled chicken breast (no skin, no seasoning) plus white rice
Lean ground turkey (well cooked and drained) plus rice
Plain scrambled egg (small portion) plus rice

Portion guide: Start small. A common starting point is about 25% to 50% of your dog’s usual daily amount split into 4 to 6 small meals for the first day, then adjust based on stool quality and your vet’s advice. If stools improve after 24 hours, gradually increase meal size and reduce frequency.

Pumpkin: helpful for some dogs

Plain canned pumpkin (not pumpkin pie filling) can add gentle fiber that helps some dogs firm up. A common starting point is about 1 teaspoon per 10 pounds of body weight mixed into food, up to a few tablespoons for very large dogs. Too much fiber can worsen gas or diarrhea, so start low and stop if it does not help.

When can I go back to normal food?

Once stools are normal for 24 to 48 hours, transition slowly over 3 to 5 days. Mix increasing amounts of regular food into the bland diet.

Action tip: Take a quick photo of each stool on day one and day two. It sounds silly, but it helps you compare improvement clearly and gives your vet useful information if you end up calling.

Do probiotics help?

Often, yes. Some studies suggest certain veterinary probiotics can help shorten the duration of acute diarrhea and support gut microbiome balance, especially after stress, antibiotics, or diet changes. Results can be product and strain specific.

Choose a product formulated for pets, ideally with clear strain identification and quality control. If your dog is immunocompromised, talk with your vet first.

Mild vs serious

It may be mild if:

Your dog is acting normal and wants to eat
There is no vomiting
No blood is present
Diarrhea is improving within 24 to 48 hours

It may be more serious if:

Diarrhea is large-volume watery and frequent
Your dog is not interested in food for more than a day
You see mucus plus straining that continues
It keeps returning every few weeks
Weight loss, increased thirst, or poor coat quality shows up

If an adult dog is not clearly improving within 24 to 48 hours, or if symptoms are worsening at any point, call your vet. Recurring diarrhea deserves a veterinary workup. It can be as simple as a parasite that needs the right medication, or it can signal a chronic condition that needs a longer-term plan.

Age-based tips

Puppies: act fast

Puppies get dehydrated quickly, and parasites are extremely common. If a puppy has watery diarrhea, diarrhea with vomiting, or diarrhea lasting more than 12 to 24 hours, call your vet. Bring a fresh stool sample if possible. If your puppy is not fully vaccinated, ask about parvo risk and isolation precautions.

Adults: look for triggers

For adult dogs, think through the last 72 hours:

New treats, chews, bones, or bully sticks?
Trash raid or greasy people food?
New bag of food, new protein, or new topper?
Boarding, grooming, visitors, travel, storms, fireworks?
Antibiotics or pain medication?

Removing the trigger plus a bland diet and, if your vet agrees, a probiotic often resolves the issue.

Seniors: call sooner

Seniors have less margin for dehydration and are more likely to have underlying disease. If your senior dog has diarrhea plus any change in drinking, appetite, energy, or weight, I recommend calling the vet sooner rather than later.

What your vet may do

If diarrhea is persistent, severe, or accompanied by other symptoms, your veterinarian may suggest:

Fecal testing (including Giardia and parasite screening)
Parvovirus test for at-risk puppies
De-worming even with a negative test in some cases, depending on history
Bloodwork to check hydration, electrolytes, organ function, inflammation
Pancreatitis testing if vomiting, abdominal pain, or fatty-food exposure is suspected
X-rays or ultrasound if a foreign body is possible
Diet trial for food sensitivity or inflammatory bowel disease
Medication for nausea, gut inflammation, or infection when appropriate

What not to do

Do not give human anti-diarrheal meds unless your veterinarian directs you. Some are unsafe for dogs, and others can mask symptoms of a more serious problem.
Avoid Pepto-Bismol, ibuprofen, and other human medications unless your vet specifically approves them.
Do not “treat” diarrhea with high-fat foods or seasoned broth. Keep the bland diet truly bland and low fat.
Avoid abrupt food switches once your dog is improving. Transition slowly.

Contagious risk

Some causes of diarrhea (like parasites, certain infections, and parvo) can spread to other dogs. Until stools are normal:

Pick up stool promptly and wash hands after cleanup.
Limit contact with dog parks, daycare, and shared water bowls.
Keep unvaccinated puppies away from areas with heavy dog traffic.

Prevention

You cannot prevent every upset stomach, but you can reduce the odds.

Transition food slowly over 7 to 10 days when changing diets.
Keep treats predictable and avoid high-fat people food.
Use parasite prevention as recommended by your vet, and do routine fecal checks.
Secure trash and keep food scraps out of reach.
Support a calmer gut during stress with routine, slow introductions, and a vet-approved probiotic if your dog is prone to stress diarrhea.

Quick checklist

If your dog has the runs, write down:

When it started
How often your dog is going
Watery vs soft, small vs large volume
Any blood or black stool
Vomiting or not
Diet changes, new treats, possible trash access
Energy level and appetite
Any medications or supplements
Any chance of foreign body exposure (toys, socks, bones)
Whether any other pets are sick

That information helps your vet give faster, more accurate guidance.

Bottom line

Most mild diarrhea improves with hydration support and a gentle diet, and you should see clear improvement within 24 to 48 hours. But when diarrhea is watery and frequent, includes blood, comes with vomiting or lethargy, or affects a puppy or senior, do not try to tough it out at home.

If you need to call your veterinarian, use the checklist above and bring a fresh stool sample if you can. It makes the visit and the answers much faster.

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