Dog Watery Diarrhea and Vomiting (Why It Happens)

When your dog suddenly develops watery diarrhea and starts vomiting, it can be distressing and messy for both of you. These symptoms often appear quickly and may indicate anything from mild stomach upset to serious illness requiring immediate veterinary care.

We outline the common causes of watery diarrhea and vomiting in dogs, what you can do at home, and when to seek veterinary help.

Dog Watery Diarrhea and Vomiting — Why It Happens

Watery diarrhea and vomiting in dogs are most often caused by digestive irritation, infections, or dietary issues. When something upsets your dog’s gastrointestinal tract — whether it’s spoiled food, parasites, or a viral infection — the body reacts by flushing out the irritants through diarrhea and vomiting.

Sometimes, this is short-lived. But if your dog becomes lethargic, dehydrated, or the symptoms persist, it could signal something more serious like pancreatitis, parvovirus, or toxin ingestion.

Dog Watery Diarrhea and Vomiting

Dog Watery Diarrhea and Vomiting: Common Causes

1. Dietary Indiscretion 

Dogs are natural scavengers, and their curiosity can get them into trouble. Eating spoiled food, trash, or table scraps can irritate the stomach and intestines, leading to watery diarrhea and vomiting.

Dog owners often see these symptoms a few hours after ingestion. You might also notice abdominal gurgling, gas, or your dog refusing food.

While mild cases resolve in 24–48 hours with rest and hydration, repeated vomiting or ongoing diarrhea can lead to dehydration and requires veterinary evaluation.

Read more: Dog Has Watery Diarrhea With Mucus (What it means)

2. Bacterial or Viral Infections

Infections like parvovirus, coronavirus, and salmonella can cause severe watery diarrhea and vomiting, especially in puppies or unvaccinated dogs.

Parvo, in particular, is life-threatening and often accompanied by foul-smelling bloody diarrhea, lethargy, and rapid dehydration.

If your dog’s diarrhea turns bloody, or if they’re weak and can’t keep water down, it’s a red flag for immediate veterinary care. Early treatment improves the chances of recovery, especially for younger or smaller dogs.

3. Parasites (Intestinal Worms and Protozoa)

Intestinal parasites like Giardia, roundworms, and hookworms can inflame the digestive tract, leading to watery stools and intermittent vomiting.

Infected dogs may also lose weight, have a bloated belly, or pass mucus and small amounts of blood in their stool.

Puppies are particularly at risk because parasites can quickly deplete their nutrients and fluids. Routine deworming and fecal testing are key in prevention.

4. Food Allergies or Sensitivities

Some dogs react poorly to certain ingredients, especially grains, dairy, or specific proteins like chicken or beef. These sensitivities can cause chronic or recurring watery diarrhea and occasional vomiting.

If your dog’s symptoms come and go but never fully resolve, a dietary intolerance may be to blame.

Switching to a limited-ingredient or hypoallergenic diet under veterinary guidance can often help identify and eliminate the culprit.

5. Pancreatitis

Pancreatitis — inflammation of the pancreas — is a painful and serious cause of vomiting and watery diarrhea in dogs. It’s often triggered by eating fatty or greasy food, like table scraps or bacon.

Dogs with pancreatitis may hunch over in pain, refuse food, and vomit repeatedly. The diarrhea may be foul-smelling and greasy.

Because this condition can quickly lead to dehydration and organ strain, dogs with suspected pancreatitis should be seen by a vet right away.

6. Toxin Ingestion

Ingesting toxins such as chocolate, xylitol, cleaning agents, or certain plants can cause immediate vomiting and diarrhea. These substances irritate the stomach lining and can damage the liver or kidneys.

Other signs may include drooling, tremors, and seizures. If you suspect your dog ate something toxic, call your vet or an emergency clinic immediately — prompt treatment can be life-saving.

7. Stress or Sudden Change

Emotional stress, travel, or sudden changes in food can trigger “stress colitis,” a condition where the intestines become inflamed.

This leads to watery diarrhea, sometimes with mucus, and occasional vomiting. It’s more common in anxious or recently boarded dogs.

Ensuring gradual food transitions and maintaining a calm environment can help prevent stress-related digestive upset.

Related: Dog Watery Diarrhea After Beach (Why it happens)

What to Do If Your Dog Has Watery Diarrhea and Vomiting

If your dog is still alert, drinking small sips of water, and showing only mild symptoms, you can manage the situation at home for 12–24 hours.

Start by withholding food (but not water) for about 12 hours to give the digestive system a break. Offer small amounts of water or ice cubes frequently to prevent dehydration.

After the fasting period, feed a bland diet — boiled chicken with plain rice or pumpkin — in small, frequent portions. Avoid fatty or seasoned foods.

If your dog improves, gradually reintroduce their regular food over the next two to three days.

However, if your dog is vomiting continuously, lethargic, or producing watery diarrhea every hour, veterinary attention is needed. Home care is only safe for mild cases.

When to Call or Visit Your Vet

You should contact your vet immediately if your dog:

  • Vomits multiple times in a few hours

  • Has watery or bloody diarrhea lasting more than 24 hours

  • Shows signs of dehydration (dry gums, sunken eyes, weakness)

  • Refuses food or water entirely

  • Is a puppy, senior, or has an existing health condition

Your vet may perform fecal tests, bloodwork, or imaging to identify the cause. Treatment often includes fluids, anti-nausea medication, probiotics, and sometimes antibiotics or special diets.

Prompt care can prevent complications like electrolyte imbalance or severe dehydration.

Read more: Dog Watery Diarrhea No Other Symptoms (When to worry)

Key Takeaway

Watery diarrhea and vomiting in dogs are common but never something to ignore. While mild cases may resolve with rest and bland food, persistent or severe symptoms can quickly become dangerous.

Keep your dog hydrated, monitor their energy levels, and contact your vet if symptoms worsen or fail to improve within a day.

Acting early not only prevents dehydration but can uncover serious underlying conditions before they become life-threatening.

With proper care, most dogs bounce back quickly — and you’ll have peace of mind knowing you acted in time.