Diarrhea in dogs

Dog with diarrhoea

Diarrhoea in dogs: symptoms, causes and treatments

Diarrhoea in dogs is when the dog has more frequent than usual soft or liquid stools. Treatment can be simple or complex, depending on the cause.

Diarrhoea can be caused by problems in your dog’s small intestine, large intestine or other organs. To help your vet make a diagnosis, you should be able to answer questions about your dog’s diet, habits and environment, as well as specific details of the diarrhoea.

Diarrhoea in the small intestine and large intestine has different causes, requires different diagnostic tests and different treatment methods. Once your vet has narrowed down the possible causes, they can perform specific tests to determine the exact cause and appropriate treatment.

Here’s what you need to know about the symptoms, causes and treatment options for diarrhoea in dogs.

Small intestinal diarrhoea in dogs


With small intestinal diarrhoea, a dog excretes large amounts of stool, with the frequency increasing moderately – about three to five times a day. The animal has no difficulty or discomfort when defecating.

Dogs with small intestinal disease may also vomit and lose weight. Sometimes the disease leads to excessive gas production and the rumbling of gas in the abdomen is audible. Blood in the stool indicates digested blood, which colours the stool black.


  • Viruses: Diseases such as distemper, canine parvovirus and canine coronavirus often affect young, inadequately vaccinated dogs.
  • Bacteria: Infections caused by salmonella, clostridia or campylobacter – however, these bacteria can also be found in the faeces of healthy dogs and cats.
  • Parasites: Worms and giardia mainly affect young animals.
  • Foreign bodies: Ingested objects such as bones and sticks can get stuck in the intestines, cause diarrhoea and vomiting or pass through the intestinal tract and damage its lining.
  • Dietary problems: Dietary intolerance or a sudden change in diet can cause diarrhoea, possibly accompanied by vomiting.
  • Food allergies: Other symptoms may include vomiting and itchy skin.
  • Toxins: Toxins such as lead and insecticides usually cause both diarrhoea and vomiting.
  • Inflammatory bowel disease (IBD): The exact cause of IBD is unknown, but an allergic reaction to food components, bacteria or parasites is suspected. Some dog breeds, such as the Basenji, may be genetically predisposed.
  • Tumours: Intestinal tumours usually occur in older dogs.
  • Fungal infections: Infections such as histoplasmosis are common in certain regions.

Diagnosis of small intestinal diarrhoea in dogs

Veterinarians can determine the cause of small intestinal diarrhoea through various diagnostic methods, including blood tests, stool tests, X-rays, ultrasound examinations of the abdomen and endoscopies.

The vet can use endoscopy to take small biopsies of the intestinal mucosa for microscopic examination. A general anaesthetic is required for this procedure.

An endoscopy may sometimes not be sufficient to diagnose intestinal lymphosarcoma, as the biopsies only cover the top layer of the intestinal wall and the cancer cells may lie deeper. In such cases, the vet will need to perform surgery to take a larger biopsy covering the entire thickness of the intestinal wall in order to make an accurate diagnosis.

Treatment of small intestinal diarrhoea in dogs

Treatment of acute (short-term) small intestinal diarrhoea usually begins with 24 to 48 hours of food deprivation, during which time water should continue to be available. When the diarrhoea stops, dogs can be given small amounts of a mild, low-fat diet in three to six meals a day for several days. The amount of food is then gradually increased and the transition to a normal diet is made slowly.

Special diets for dogs with small intestinal diarrhoea often contain rice, as this is more digestible than other cereals.

Do not give your dog any over-the-counter diarrhoea medication without first consulting a vet. If your dog is active, not dehydrated and otherwise healthy, acute diarrhoea can often be treated at home.

If the diarrhoea is accompanied by other symptoms such as depression or lasts longer than a few days, a visit to the vet is urgently required.

Large intestine diarrhoea in dogs


Diseases of the colon cause frequent but small and soft faeces in pets, typically more than five times a day. The animal has to strain to have a bowel movement and if there is blood in the stool, it will be red and possibly mucousy.

There is usually no vomiting or weight loss with colonic diarrhoea.


Diagnosis of large intestine diarrhoea in dogs

Vets diagnose colonic diarrhoea using blood tests and faecal examinations. A rectal examination with a gloved finger can indicate the presence of rectal polyps or rectal cancer.

For a detailed examination of the large intestine, the vet will perform an endoscopy. This involves inserting either a rigid or flexible endoscope through the rectum. Due to the frequent irritation of the rectum, colon examinations are usually performed under general anaesthetic.

Treatment of large intestinal diarrhoea in dogs

Treatment depends on the specific diagnosis.

General treatment approaches often include a high-fibre diet and the administration of sulphasalazine, an anti-inflammatory drug.

Diarrhoea in dogs caused by diseases outside the intestines

In addition to diseases of the intestinal tract, diseases outside the gut can also cause diarrhoea in dogs, including kidney failure, liver failure and diseases of the pancreas.

Severe inflammation of the pancreas, known as pancreatitis, can cause damage to the pancreas and affect the production of sufficient enzymes to digest fat. This leads to pancreatic insufficiency and causes diarrhoea with fatty stools. In young animals, pancreatic insufficiency can occur due to a congenital deficiency of pancreatic enzymes.

When should you contact your vet if your dog has diarrhoea?

One or two bouts of diarrhoea in your dog, without any other symptoms, are not usually a cause for concern.

Monitor your dog’s stools to see if the situation improves. However, if your dog has more than two bouts of diarrhoea, this could indicate a serious problem. It is advisable to consult your vet if your dog has diarrhoea more than twice.

If your dog appears to be straining during bowel movements but is only passing small amounts of watery diarrhoea, this could indicate a painful blockage caused by swallowing a foreign object such as a toy. This is a serious situation that requires immediate veterinary attention. Therefore, contact your vet immediately or go to the nearest veterinary clinic for treatment.

Recurrent bouts of diarrhoea over a short period of time can also be a sign of a serious health problem, especially if your dog is very young, old or has a weakened immune system. There is a possibility that your dog is suffering from a life-threatening infection such as parvovirus or salmonella.

If your dog shows other symptoms in addition to diarrhoea, please take him to the vet as soon as possible. These symptoms include:

  • Blood in the faeces
  • Unusual drooling
  • Vomiting
  • Loss of appetite
  • Weakness
  • Signs of dehydration (sunken, dry-looking eyes, dry nose or dry, sticky gums)

Treatment of diarrhoea in dogs

When it comes to treating diarrhoea in dogs, it is important not to administer any human medication without first consulting your vet. Many human medications can be toxic to dogs and cause further complications.

If your dog has mild diarrhoea with no other symptoms, you should first give him 12-24 hours rest by not giving him anything to eat.

You can also try switching him to a bland diet for 24-48 hours. Cooked brown rice with chicken or unsweetened tinned pumpkin are good options to relieve diarrhoea in dogs. Once the bowel movements have normalised, you can slowly switch back to his normal diet.

In addition, natural yoghurt, probiotics, peeled boiled potatoes, cottage cheese or a boiled egg without added oil can help to soothe your dog’s stomach.

The Moro carrot soup (or Moro Soup) has also become an absolute insider tip.

Moro’s carrot soup is an extremely popular and effective household remedy for treating diarrhoea. This soup originally comes from paediatric medicine and was developed by Professor Dr Ernst Moro around 1908. In the meantime, it has also established itself among dog owners as an effective remedy for treating diarrhoea.

Chronic diarrhoea in dogs can indicate a sensitive stomach. If your dog regularly suffers from diarrhoea and no other causes are found, your vet may be able to recommend special medication or a diet.

For your dog’s health, it is always advisable to play it safe and speak to your vet to determine the best treatment plan for your dog’s diarrhoea.

Note: The information provided here is for informational purposes only and does not constitute veterinary advice. For an accurate diagnosis and treatment for your pet, please consult your veterinarian.