What Causes Diarrhoea in Dogs? Common Causes & Care Tips

Diarrhoea in dogs is a common issue that can range from a minor inconvenience to a serious health concern. Understanding the causes of diarrhoea in dogs, recognising symptoms, and knowing when to seek veterinary advice is essential for every responsible pet owner. This article explains the most common reasons why dogs develop diarrhoea, the associated signs, treatment options, and prevention tips, all tailored to the latest UK veterinary standards in 2025.

What Is Diarrhoea in Dogs?

Diarrhoea is characterised by frequent, loose, or watery stools. It is a symptom rather than a specific disease, indicating that something is affecting your dog’s digestive system. Causes can vary widely, from mild dietary issues to serious infections or chronic conditions.

Common Causes of Diarrhoea in Dogs

1. Eating Something That Didn’t Agree With Them

One of the most frequent causes is dietary indiscretion—dogs eating rubbish, roadkill, discarded food like kebabs, or simply eating food too rich, fatty, or salty. Canine digestive systems are sensitive, so even normal human food can upset their stomach.

2. Poisoning or Toxicity

Ingestion of toxic substances such as chocolate, certain plants, or chemicals can cause diarrhoea as the body tries to purge the poison. Chocolate contains theobromine, which is harmful to dogs even in small amounts. If you suspect poisoning, contact your vet immediately.

3. Allergies and Food Sensitivities

Food allergies or sensitivities, including intolerance to lactose from cow’s milk, can provoke diarrhoea. Some dogs develop digestive upset due to certain proteins, grains, or additives in their diet.

4. Stress and Anxiety

Changes in routine, environment, or emotional stress can trigger diarrhoea. Dogs experiencing anxiety may develop digestive symptoms due to the gut-brain connection impacting their gastrointestinal system.

5. Infections

Bacterial infections (like Salmonella), viral infections (such as parvovirus, especially concerning in unvaccinated puppies), and other infections can result in diarrhoea. Vaccination and hygiene are important preventative measures.

6. High Worm Count

Parasite infestations from roundworms, hookworms, or protozoa like giardia are common causes. Regular worming according to vet advice is vital to prevent parasites causing digestive upset and malnutrition.

7. Heatstroke or Dehydration

Heat stress can cause systemic illness including diarrhoea. Certain breeds like the French Bulldog puppies are particularly prone to heatstroke due to their brachycephalic (short-nosed) build.

8. Internal Blockages

Dogs eating foreign objects such as parts of toys or other indigestible materials risk internal blockages, which can cause diarrhoea along with severe distress. Immediate vet attention is necessary if blockage is suspected.

9. Bowel Diseases

Chronic or recurrent diarrhoea may be due to bowel conditions like inflammatory bowel disease requiring veterinary diagnosis and management.

Can You Give Dogs Calpol?

Important: Never give dogs Calpol or any medication containing paracetamol. It is toxic and potentially fatal. Always consult your vet before giving any medication to your dog.

Is Chocolate Bad for Dogs?

Chocolate is toxic to dogs because of theobromine, which dogs cannot metabolise effectively. Even small amounts can lead to vomiting, diarrhoea, seizures, or death. Contact a vet immediately if your dog has eaten chocolate.

Symptoms to Watch For

• Loose or watery stools
• Blood or mucus in faeces
• Vomiting or loss of appetite
• Lethargy or discomfort
• Signs of dehydration like dry gums and sunken eyes

Treatment and When to See a Vet

For mild diarrhoea, withhold food for 12-24 hours (but not water to prevent dehydration), then offer a bland diet like boiled chicken and rice gradually. Persistent, severe, or bloody diarrhoea, especially in puppies or elderly dogs, requires veterinary attention. Vets may recommend diagnostic tests, fluid therapy, medications, and special diet plans based on the diagnosis.

Prevention Tips

• Keep a consistent, high-quality diet and avoid abrupt changes
• Prevent access to rubbish, toxic substances, and harmful human foods
• Keep up-to-date with worming and vaccinations
• Reduce stress and maintain routine for your dog’s wellbeing
• Choose reputable breeders or adoption sources for new dogs

Being vigilant about your dog’s diet, environment, and health can prevent many episodes of diarrhoea. Responsible ownership and early veterinary involvement ensure your dog remains happy and healthy.