Understanding Why Dogs Get Diarrhoea
Diarrhoea is one of the most common reasons dog owners contact their vet, and for good reason — loose, watery, or unusually frequent stools can signal anything from a minor dietary indiscretion to a serious underlying condition. Knowing the difference is the key to handling it correctly.
The digestive tract in dogs is sensitive to change. A sudden switch in food, scavenging something questionable on a walk, or even emotional stress can disrupt the delicate balance of gut bacteria and fluid absorption in the large intestine, resulting in diarrhoea. Most single episodes resolve within 24 to 48 hours without intervention.
Common Causes of Diarrhoea in Dogs
Before reaching for any remedy, it helps to identify what might have triggered the episode. The most frequent causes fall into several broad categories.
Dietary Causes
- Eating rubbish, spoiled food, or foreign material
- A sudden change in diet without a gradual transition
- Food intolerance or sensitivity to a specific ingredient
- Eating too much fat, particularly rich or greasy human food
- Lactose intolerance triggered by dairy products
Infectious Causes
- Bacterial infections such as Salmonella or Campylobacter
- Viral infections including parvovirus and coronavirus
- Intestinal parasites such as Giardia, roundworms, or hookworms
- Fungal infections, though these are less common
Medical and Systemic Causes
- Inflammatory bowel disease
- Pancreatitis
- Liver or kidney disease
- Addison's disease (hypoadrenocorticism)
- Certain medications, including antibiotics and NSAIDs
Acute Versus Chronic Diarrhoea
Acute diarrhoea comes on suddenly and typically lasts fewer than three to five days. It is usually self-limiting and responds well to supportive care at home. Chronic diarrhoea, on the other hand, persists for three weeks or longer, or recurs repeatedly over time. Chronic cases almost always require veterinary investigation to identify the root cause.
The location of the problem also matters. Small intestinal diarrhoea tends to produce large volumes of loose stool without urgency. Large intestinal diarrhoea (colitis) typically produces smaller amounts of mucus-coated or bloody stool with obvious straining and increased frequency. Identifying which pattern your dog is showing helps your vet narrow down the cause quickly.
Safe Home Treatment for Mild Cases
For a healthy adult dog with a single episode of soft stool and no other symptoms, a period of watchful management at home is entirely reasonable.
Fasting
Withholding food for 12 to 24 hours gives the gut lining time to recover and reduces the workload on the digestive system. Water must always remain available. Do not fast puppies, elderly dogs, or dogs with known medical conditions without veterinary guidance, as these animals are more vulnerable to hypoglycaemia and dehydration.
A Bland Diet
Once your dog is ready to eat again, introduce a bland, easily digestible diet for two to three days before gradually transitioning back to their regular food. Plain boiled white rice with plain boiled chicken breast (no skin, no seasoning) is the classic approach. Plain boiled potato or scrambled egg with no butter or salt are also reasonable options. Keep portions small and offer meals three to four times per day rather than one large serving.
Probiotics
Canine-specific probiotic supplements can help restore a healthy microbial balance in the gut. Research published in the Journal of Veterinary Internal Medicine has demonstrated that Enterococcus faecium strain SF68 reduces the duration of acute diarrhoea in dogs. Look for products formulated specifically for dogs rather than human probiotics, which may not contain appropriate bacterial strains at useful concentrations.
Pumpkin
Plain canned pumpkin (not pumpkin pie filling) contains soluble fibre that absorbs excess water in the gut and can firm up loose stools. One to four tablespoons added to a bland meal, depending on your dog's size, is a practical and evidence-supported home remedy.
When to Call the Vet
Home management is appropriate only for mild, isolated episodes in otherwise healthy adult dogs. There are clear situations where veterinary attention is needed promptly.
- Blood in the stool — either bright red or dark and tarry (melaena)
- Diarrhoea lasting more than 48 to 72 hours despite home care
- Vomiting alongside diarrhoea, particularly if your dog cannot keep water down
- Signs of lethargy, weakness, or collapse
- Suspected ingestion of a toxin or foreign body
- A known health condition such as diabetes, Addison's disease, or liver disease
- Puppies under six months of age — they dehydrate rapidly
- Elderly dogs who may lack the physiological reserves to cope
Dehydration is the most immediate risk with diarrhoea. You can perform a rough assessment by gently pinching the skin at the back of the neck — in a well-hydrated dog it snaps back immediately. If the skin remains tented or returns slowly, or if your dog's gums are pale, dry, or tacky rather than moist and pink, seek veterinary care without delay.
Preventing Recurring Diarrhoea
Prevention is considerably easier than treatment. The single most effective step you can take is to transition between foods gradually over seven to ten days, mixing increasing proportions of the new food with the old. This allows the gut microbiome time to adapt.
Keeping your dog's parasite prevention up to date is equally important. Regular faecal screening, particularly for dogs with outdoor access or those who scavenge, can catch parasitic infections before they cause chronic problems. A consistent, species-appropriate diet without frequent changes or rich treats will also reduce the frequency of dietary-triggered episodes.
Stress is an underappreciated trigger. Dogs experiencing changes in routine, new environments, or separation anxiety frequently develop stress colitis. Addressing the underlying behavioural cause and supporting gut health with a daily probiotic during periods of change can make a meaningful difference.