Puppy Diarrhea: Causes, Treatment & When to Call the Vet

Key takeaways:

• Puppy diarrhea is common, but puppies dehydrate faster than adults, so the bar for calling the vet is lower.
• More than 30% of US dogs under 6 months old shed roundworm eggs, per the Companion Animal Parasite Council.
• Puppies 6 to 20 weeks old are among the groups at highest risk of parvovirus, according to the AVMA.
• Don't fast a puppy. Small, frequent bland meals keep blood sugar up, which matters most in toy breeds.
• Call the same day if diarrhea lasts past 24 hours, if your puppy is under 12 weeks, or if there's vomiting, blood or lethargy.

Puppy diarrhea needs faster attention than adult dog diarrhea. The causes are usually ordinary (a diet switch, rehoming stress, worms or a scavenged snack), but puppies have small fluid reserves and are among the dogs most at risk from parvovirus. A rule of thumb: what you'd watch for two days in an adult dog, give a puppy one day at most.

Is it normal for puppies to have diarrhea?

A soft stool or two is common, especially in the first week home, but it isn't something to ignore. Puppies pick up parasites easily, and a minor upset can tip into dehydration within a day. Normal puppy poop is formed, brown and frequent (young puppies poop a lot). Our dog poop color chart decodes yellow, slimy mucus-coated stool and other changes.

Puppy diarrhea by age: likely causes and how urgent it is

Causes shift as your puppy grows. Use this as a guide, and call your vet whenever you're unsure:

Parasites run through every row. The Companion Animal Parasite Council reports that more than 30% of US dogs under 6 months old shed roundworm eggs, and that some studies suggest virtually all puppies are born infected, which is why CAPC recommends deworming at 2, 4, 6 and 8 weeks. Older puppies keep picking them up: in the DOGPARCS study, about 42% of dog-park visitors under a year old tested positive for worms or Giardia. See what worms in dog poop look like.

Why does my puppy have diarrhea?

Most cases come down to one of these:

• A sudden food change, often made overnight in a new home. Our guide on how to transition your dog to fresh food shows a gradual mix.
• Stress. CAPC notes that the stress of relocation to a new owner can make coccidiosis worse.
• Parasites, from roundworms to Giardia; here's how to tell if your dog has worms.
• Eating things they shouldn't, which peaks during puppy teething. Swallowed objects can cause an intestinal blockage.
• Overfeeding or too many treats. Check portions against our puppy feeding guide.
• Parvovirus and other infections in puppies who aren't fully vaccinated.

"77.1% of puppies aged 5 to 14 weeks were shedding at least one intestinal virus or parasite, and 24.8% had abnormal stool, in a 2014 study of 266 puppies from 29 breeding kennels." - Preventive Veterinary Medicine

Puppy has diarrhea but is still playful, eating and drinking: what to do

Home care suits only a puppy over 12 weeks who's playful, eating and drinking, with no vomiting or blood.

• Keep feeding, smaller and blander. Offer small portions every few hours instead of fasting. Toy and miniature puppies, such as Chihuahuas, are at increased risk of low blood sugar, and a 2018 review in the Canadian Veterinary Journal lists too little food among the causes. Our guide on what to feed a dog with diarrhea covers bland options and portions.
• Keep fresh water in reach. If your puppy isn't drinking, call your vet.
• Watch closely for 24 hours. Track energy, appetite, stool count and gum color (pink and moist is good).
• Ask before adding anything. Plain pumpkin for dogs or probiotics for dogs may be fine, but check with your vet first.
• Bag a fresh sample. If you end up at the vet, a fecal test turns guesswork into a diagnosis.

Improvement should show within a day; if things get worse, call. Cornell's Riney Canine Health Center mentions withholding food for 12 to 24 hours as a tip for mild dog diarrhea, but that general advice doesn't fit young puppies, especially toy breeds.

When is puppy diarrhea an emergency?

Go to a vet right away for:

• Bloody diarrhea, or black, tarry stool; see bloody diarrhea in dogs for what the colors mean
• Vomiting plus diarrhea, which drains fluids fast; foamy white vomit in puppies counts
• Lethargy, weakness or a puppy that won't play
• Refusing water, or signs of dehydration: tacky gums, sunken eyes, skin that stays tented
• Any diarrhea in an unvaccinated or partly vaccinated puppy
• A swallowed toxin or object. Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435

The American Veterinary Medical Association adds belly pain and bloating, fever or low body temperature, and drooling to parvo's warning signs, and advises calling your veterinarian immediately.

What most puppy diarrhea guides don't tell you

A positive stool test isn't always the whole story. In the Grellet kennel study, three in four puppies carried a gut virus or parasite, but only one in four had abnormal stool. Normal-looking poop doesn't prove a puppy is parasite-free either, which is why routine deworming happens regardless.

Even dogs sick with parvo do better fed. In a trial of 30 dogs hospitalized with severe parvo, those fed by tube from 12 hours after admission had their appetite, vomiting and diarrhea return to normal a day sooner than dogs kept off food, and they gained weight. That was hospital care with a feeding tube, but it's one more reason not to starve a sick puppy at home.

Vaccinated doesn't mean protected yet. The AVMA explains that maternal antibodies can fade before a puppy's own immunity kicks in, so even vaccinated puppies occasionally get parvo. The series runs from 6 to 8 weeks until 16 weeks or older. Our take: until then, skip dog parks and pet-store floors, and treat diarrhea with vomiting as parvo until your vet says otherwise.

Once the gut settles, a consistent growth diet helps you avoid a frequent trigger, the abrupt food switch. Spot & Tango recipes are formulated with pet nutritionists to meet AAFCO standards for all life stages, including growth of large-size dogs; see can puppies have fresh dog food for how to start.

Frequently asked questions

How long does puppy diarrhea last?

Mild, diet-related diarrhea should improve within 24 hours of small bland meals and clear within a couple of days. Anything longer, anything getting worse, or any diarrhea with vomiting or low energy needs a vet and probably a fecal test.

Can I give my puppy Imodium or Pepto-Bismol?

Not without your vet's direction. Doses are hard to get right for a small body, and masking diarrhea can hide parvo or parasites. Washington State University's vet hospital lists loperamide (Imodium) among the drugs that can cause serious reactions in dogs with the MDR1 gene mutation, common in herding breeds.

My puppy has diarrhea but is acting fine. Should I worry?

Pay attention, but don't panic. A bright, eating puppy over 12 weeks with one or two soft stools can be watched for 24 hours on small bland diet meals. Call your vet if it continues past a day or vomiting or blood appears.

What does parvo diarrhea look like?

The AVMA describes it as severe and often bloody, usually with vomiting, lethargy and appetite loss. Appearance alone can't confirm parvo; a fecal test can. Those signs need a vet immediately, vaccinated or not.

What can I give my puppy for diarrhea?

For a bright puppy over 12 weeks: small, frequent bland meals and fresh water, and nothing from your own medicine cabinet. Your vet may add a veterinary probiotic, a dewormer or a GI diet once a fecal test shows the cause. After that, one consistent diet and our tips on how to firm up dog poop help.

The bottom line: Puppy diarrhea deserves quick attention and a low bar for calling the vet: small bland meals and close watching for mild cases, same-day care for anything more. Build your puppy's plan with our recipe quiz when you're ready for a steady growth diet.

Questions about puppy feeding? Our customer care team is happy to help.

About this article

Written by the Spot & Tango editorial team, which covers canine nutrition and health for dog owners. Reviewed by a licensed veterinarian; facts and figures checked.

References & Sources:

• American Veterinary Medical Association, Canine parvovirus (accessed 2026). https://www.avma.org/resources-tools/pet-owners/petcare/canine-parvovirus
• Companion Animal Parasite Council, Ascarid guidelines (updated Feb 2025). https://capcvet.org/guidelines/ascarid/
• Companion Animal Parasite Council, Coccidia guidelines (updated Feb 2025). https://capcvet.org/guidelines/coccidia/
• Grellet A. et al., Risk factors of weaning diarrhea in puppies housed in breeding kennels, Preventive Veterinary Medicine (2014). https://pubmed.ncbi.nlm.nih.gov/25175676/
• Stafford K. et al., Detection of gastrointestinal parasitism at recreational canine sites in the USA: the DOGPARCS study, Parasites & Vectors (2020). https://pmc.ncbi.nlm.nih.gov/articles/PMC7268625/
• Idowu O., Heading K., Hypoglycemia in dogs: causes, management, and diagnosis, Canadian Veterinary Journal (2018). https://pmc.ncbi.nlm.nih.gov/articles/PMC5949948/
• Mohr A.J. et al., Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis, Journal of Veterinary Internal Medicine (2003). https://pubmed.ncbi.nlm.nih.gov/14658714/
• Cornell Riney Canine Health Center, Diarrhea (accessed 2026). https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-topics/diarrhea
• Washington State University Veterinary Teaching Hospital, Is your pet at risk of an adverse reaction to common drugs? (2021). https://hospital.vetmed.wsu.edu/2021/08/05/is-your-pet-at-risk/
• ASPCA Animal Poison Control Center. https://www.aspca.org/pet-care/aspca-poison-control