Why Is My Dog Having Diarrhoea?

Diarrhoea in dogs is a symptom rather than a disease. It can be caused by something relatively minor, such as eating unfamiliar food or a sudden diet change, or by more serious conditions including infections, intestinal parasites, pancreatitis, poisoning, or underlying organ disease. While mild diarrhoea may resolve on its own, persistent diarrhoea or diarrhoea accompanied by other symptoms should be assessed by a veterinarian.

Mild diarrhoea is often caused by temporary digestive upset.

Many dogs develop diarrhoea after eating spoiled food, table scraps, or switching to a new diet too quickly. These cases are often short-lived, but your dog should still be monitored closely.

Persistent diarrhoea may indicate an underlying medical condition.

Diarrhoea lasting longer than 24 hours or occurring repeatedly can be a sign of infection, parasites, inflammatory bowel disease, pancreatitis, or problems affecting other organs.

Puppies and senior dogs are at greater risk.

Young puppies and older dogs can become dehydrated more quickly than healthy adult dogs. They should be examined sooner if diarrhoea develops.

What causes diarrhoea in dogs?

Diarrhoea occurs when the digestive system is unable to properly absorb water or when inflammation causes food to move too quickly through the intestines. The underlying cause can range from a simple dietary indiscretion to a serious illness requiring urgent treatment.

Common causes include:

• Eating spoiled food or garbage

• Sudden changes in diet

• Food intolerance or food allergies

• Rich or fatty foods

• Intestinal parasites

• Bacterial infections

• Viral infections (such as parvovirus)

• Stress or anxiety

• Certain medications

• Pancreatitis

• Liver disease

• Kidney disease

• Inflammatory bowel disease

• Foreign body ingestion

• Poisoning

What does my dog's diarrhoea look like, and what could it mean?

The appearance of your dog's stool can provide useful clues about the possible cause of diarrhoea, but it cannot diagnose the problem on its own. Your veterinarian will also consider your dog's medical history, physical examination, and any diagnostic tests before determining the underlying cause.

When should I be concerned about the appearance of my dog's stool?

Bloody diarrhoea, black tarry stools, or diarrhoea that continues for more than 24 hours should always be assessed by a veterinarian. Even mild diarrhoea may require medical attention if your dog is vomiting, appears lethargic, refuses food or water, or shows signs of dehydration.

Why is my dog having diarrhoea but acting normally?

Not all cases of diarrhoea indicate a serious illness.

Dogs may continue to behave normally if the diarrhoea is caused by:

• Eating something unusual

• A sudden diet change

• Mild stress

• Temporary stomach irritation

• A minor digestive upset

Close monitoring at home for the next 24 hours is generally appropriate if your dog has mild diarrhoea and continues to:

• Be bright and alert

• Eat normally

• Drink water

• Remain active and energetic

If the diarrhoea persists or your dog's condition changes, arrange a veterinary examination.

Can food cause diarrhoea in dogs?

Yes. Food is one of the most common causes of diarrhoea.

Examples include:

• Sudden changes in diet

• Rich table scraps

• Fatty foods

• Dairy products

• Spoiled food

• Food allergies

• Food intolerance

To reduce the risk of diarrhoea, introduce any new diet gradually over 7 to 10 days, mixing increasing amounts of the new food with the current diet.

Can parasites cause diarrhoea?

Yes. Intestinal parasites are a common cause of diarrhoea, especially in puppies and dogs that regularly visit parks or outdoor areas.

Common parasites include:

• Roundworms

• Hookworms

• Whipworms

• Giardia

• Coccidia

A faecal examination helps identify parasites so that targeted treatment can be prescribed.

Could my dog have eaten something it shouldn't?

Dogs frequently develop diarrhoea after ingesting inappropriate or toxic items.

Common examples include:

• Garbage

• Bones

• Toys

• Plastic

• Chocolate

• Grapes

• Raisins

• Xylitol-containing products

• Household chemicals

• Toxic plants

If you suspect your dog has eaten a toxic substance or foreign object, seek veterinary care immediately.

How will a veterinarian determine the cause?

Your veterinarian will begin with a thorough history and physical examination.

Depending on your dog's symptoms, additional tests may include:

• Faecal examination

• Blood tests

• Urinalysis

• X-rays

• Ultrasound

• Parvovirus testing

• Gastrointestinal function tests

These investigations help identify the underlying cause and guide the most appropriate treatment.

How is diarrhoea treated?

Treatment for diarrhoea depends on the underlying cause rather than the symptom itself. Some dogs recover with dietary management and supportive care, while others require medication, intravenous fluids, hospitalisation, or surgery. Your veterinarian will first determine why your dog has diarrhoea before recommending the most appropriate treatment.

The table below outlines some common causes of diarrhoea and the treatments that may be recommended.

Why is it important to identify the cause before starting treatment?

Diarrhoea is a symptom, not a diagnosis. Treating the symptom without identifying the underlying cause may delay appropriate care and allow serious conditions such as intestinal obstruction, pancreatitis, poisoning, or infectious diseases to worsen.

Should I monitor my dog’s diarrhoea or visit the veterinarian?

A mild episode of diarrhoea may resolve without treatment, but some situations require prompt veterinary attention. Use the guide below as a general reference. If you are unsure, it is always safest to contact your veterinarian.

Contact a veterinarian if your dog's diarrhoea lasts longer than 24 hours, contains blood, is accompanied by vomiting, lethargy, fever, abdominal pain, or loss of appetite, or if your dog is a puppy, senior, or has an existing medical condition. Prompt veterinary care can help prevent dehydration, identify the underlying cause, and ensure your dog receives the most appropriate treatment.

Frequently Asked Questions

Can stress cause diarrhoea in dogs?

Yes. Stress from travel, boarding, thunderstorms, moving house, or changes in routine can sometimes cause temporary diarrhoea. However, ongoing or severe diarrhoea should always be investigated to rule out medical conditions.

Is diarrhoea contagious to other dogs?

Some causes of diarrhoea, including certain viruses, bacteria, and parasites, can spread to other dogs. Until the cause is known, avoid dog parks, daycare facilities, and close contact with other pets.

Can I give my dog human anti-diarrhoea medication?

No. Some human medications can be harmful to dogs or mask serious disease. Always consult a veterinarian before giving your dog any medication.