Puppy Diarrhea and Not Eating: Here’s Why and What to Do

Common Causes of Puppy Diarrhea and Not Eating

Let’s break down some of the most common reasons puppies experience these two symptoms:

1. Dietary Changes or Sensitivities

Puppies’ stomachs are sensitive, and switching food too quickly can cause gastrointestinal upset.

Triggers include:

• Sudden food changes

• Treats or table scraps

• Eating non-food items (grass, dirt, toys)

• Transitioning from mother’s milk to solids

Puppy-Specific Concern:
Puppies are curious chewers and often explore the world with their mouths, making them more likely to ingest inappropriate items that upset their digestive system.

2. Parasites

Intestinal parasites such as roundworms, hookworms, coccidia, and giardia are extremely common in puppies and a top cause of diarrhea and appetite loss.

Signs of parasites include:

• Diarrhea (sometimes with mucus or blood)

• Pot-bellied appearance

• Weight loss

• Poor coat quality

Puppies should be routinely dewormed beginning at 2-3 weeks of age, as parasites can pass from the mother—even before birth.

Related: Puppy won’t eating grass (Here’s why)

3. Infections (Viral or Bacterial)

Distemper, parvovirus, and coronavirus are severe, sometimes deadly diseases that often begin with diarrhea and refusal to eat.

Parvovirus, in particular, is a leading concern. It spreads easily and strikes quickly, especially in unvaccinated puppies.

Symptoms include:

• Bloody, foul-smelling diarrhea

• Vomiting

• Lethargy

• Loss of appetite

• Fever or low body temperature

If you suspect your puppy may have parvo or a similar infection, seek emergency veterinary care immediately.

4. Stress and Environment Changes

Even small environmental changes can stress a puppy, especially if they’ve just been adopted or moved to a new home.

Stress can lead to:

• Digestive upset

• Mild diarrhea

• Picky eating or refusing food

• Increased vocalization, pacing, or hiding

Puppies also experience “stress colitis,” which is inflammation of the colon due to stress, leading to soft or loose stool and loss of appetite.

5. Vaccination Side Effects

Some puppies may develop mild digestive issues, including temporary diarrhea and reduced appetite, after vaccinations.

While this reaction is usually short-lived, contact your vet if symptoms persist for more than 24 hours.

6. Teething and Oral Pain

Teething can reduce appetite in puppies, and discomfort in the mouth might cause them to chew instead of eat.

However, teething alone should not cause diarrhea. If both symptoms are present, look for additional causes such as dietary issues or infection.

7. Toxin or Foreign Object Ingestion

Puppies love to chew and may swallow toxic items like:

• Houseplants

• Human medications

• Chocolate or xylitol-containing treats

• Cleaning products

• Small toys or fabric

These can cause serious gastrointestinal issues including vomiting, diarrhea, pain, and complete refusal to eat.

8. Fading Puppy Syndrome (in Neonates)

In very young puppies (under 6–8 weeks), not eating and diarrhea can be part of Fading Puppy Syndrome, where they fail to thrive and deteriorate rapidly.

Signs include:

• Constant crying

• Weakness

• Diarrhea

• Poor suckling

• Rapid weight loss

Immediate veterinary intervention is critical in such cases.

How Long Can Puppies Go Without Eating When They Have Diarrhea?

Puppies are much more sensitive to fasting than adult dogs. Skipping more than 12–24 hours of food, especially with ongoing diarrhea, can lead to serious complications like hypoglycemia or dehydration.

Avoid extended fasting unless instructed by a veterinarian. Instead, offer small amounts of bland, easily digestible food like:

• Boiled chicken (no skin or seasoning)

• Plain white rice

• Canned pumpkin (not pie filling)

Puppy Has Diarrhea and Not Eating but Drinking Water

It’s a positive sign if your puppy is still drinking water—it helps prevent dehydration. However, if the diarrhea continues and your puppy refuses food for more than 12 hours, consult a vet.

Watch for signs like:

• Lethargy

• Vomiting

• Blood in stool

• Crying or signs of abdominal pain

Can Not Eating Cause Diarrhea in Puppies?

While not eating doesn’t directly cause diarrhea, the two are often linked to the same underlying issue. Prolonged fasting may irritate the stomach due to bile buildup, potentially triggering vomiting or loose stools.

In puppies, skipping meals can quickly snowball into greater problems because of their rapid metabolism and low body reserves.

Related: Dog diarrhea: A guide

Puppy Has Diarrhea and Not Eating or Drinking — When It’s an Emergency

If your puppy is not eating or drinking along with diarrhea, this is a veterinary emergency. Puppies can dehydrate much faster than adults, and dehydration can be life-threatening.

Call a vet immediately if:

• Your puppy is lethargic or unresponsive

• Diarrhea is bloody or persistent

• Vomiting is also present

• Gums are pale or dry

• They haven’t eaten or drunk in 12+ hours

What to Do if Your Puppy Has Diarrhea and Won’t Eat

1. Stop feeding treats or new foods

2. Offer a bland diet (rice and boiled chicken)

3. Ensure fresh water is available at all times

4. Monitor for other symptoms

5. Call your vet if symptoms last more than 12–24 hours

Never give over-the-counter human medications unless prescribed by your vet—some are toxic to puppies.

Key Takeaway

Diarrhea and appetite loss in puppies are concerning and should never be ignored. Because puppies have underdeveloped immune and digestive systems, even a mild case can become serious quickly.

If your puppy is showing these symptoms, early veterinary intervention can prevent dehydration and identify underlying causes before complications arise.

Always err on the side of caution when it comes to young pups—your fast action could save their life.