Sheet
Diarrhea
Loose or watery stools, more often than usual. It's a symptom with many causes: a sudden food change, eating something they shouldn't, stress, parasites or viruses.
Go to the vet now if…
- There's blood in the stool, or it's black and tarry.
- Vomiting as well, especially repeated vomiting or blood in the vomit.
- Very tired or weak, or not eating.
- Not drinking.
- Your puppy is very young or very small, or not fully vaccinated (it could be parvovirus).
- A painful or swollen belly.
- It lasts more than 24 hours, or it's severe or frequent (several times in a few hours).
How you notice it
- Soft, mushy or watery stools.
- Pooping more often or more urgently; there may be accidents indoors.
- Mucus or blood in the stool.
- Vomiting, less appetite or less energy.
What to do
- Call your vet and describe how many times it's happened, what the stools look like, any vomiting, whether your puppy eats and drinks, vaccines, and any food change.
- Keep fresh water within reach at all times and encourage drinking.
- Don't withhold food unless your vet says so: fasting can be dangerous for puppies. Ask what to feed.
- Bring a fresh stool sample.
- Don't give human medicines, anti-diarrheals included, unless your vet tells you to.
- Clean up right away, wash your hands, and keep your puppy away from other dogs until you know the cause.
Does it spread?
- To other dogs: it depends
- To people: it depends
It depends on the cause. Parasites or viruses can spread to other dogs, and some parasites (like giardia or roundworms) can pass to people. Until you know, keep things clean and keep your puppy apart from other dogs.
How to prevent it
- Switch foods gradually, over a week or two.
- No fatty or salty people food.
- Keep vaccines and deworming up to date.
Sources
- Diarrhea (canine health topics; edited and updated 3/2024 by Riney Canine Health Center veterinarians)
- Why does my puppy have diarrhoea?
- Diarrhoea in dogs (PDSA Pet Health Hub; written by vets and vet nurses, May 2023)
- Disorders of the Stomach and Intestines in Dogs - Dog Owner Version (Defarges A et al.; updated Jun 2026)
- 13 Animal emergencies that require immediate veterinary consultation and/or care
- Canine parvovirus (pet owners)
- Medication Errors Happen to Pets, Too (Consumer Update, content current as of 13 May 2021)
- Never Give Medications for People to Pets (Bryan L, Pet Health Columns, 19 Sept 2025)
- Disorders Caused by Protozoa in the Digestive System of Dogs - Dog Owner Version (Patton S, Constable PD; updated Sept 2024)
- ESCCAP Modular Guide 1: Worm control in dogs and cats (2026 update) - clinical signs and preventing zoonotic infection
- CAPC Guidelines: Ascarid (Dogs) - clinical signs, zoonosis and control (updated 28 Feb 2025)
- ESCCAP Guideline 06: Control of Intestinal Protozoa in Dogs and Cats (3rd edition, March 2025)
- Nobivac DHPPi lyophilisate for suspension for injection for dogs - Summary of Product Characteristics (last revised Aug 2025, approved Dec 2025)
- Versican Plus DHPPi lyophilisate and solvent for suspension for injection for dogs - Summary of Product Characteristics (revised Mar 2024)
- VANGUARD CPV suspensión inyectable para perros - Ficha técnica (RCP rev. 02/2025)
- Vaccine Failure and Other Adverse Events in Animals - Professional Version (Tizard IR; full review Oct 2023, updated Sep 2024)
- Directrices de 2024 para la vacunación de perros y gatos (traducción al español de Squires RA et al., J Small Anim Pract 2024): refugios y preguntas sobre glucocorticoides
This is general information, not a diagnosis. Your vet is the one who can tell what's wrong and what to do.