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Diarrhoea in Dogs: What Can I Do About It?

Just like us, dogs can get upset stomachs from time to time too. Learn how you can help manage your dog's diarrhoea and when you...

Diarrhoea is extremely common in dogs and deciding when to take your dog to the vets can be challenging. Keep on reading to learn about the causes of your dog's upset stomach, for some guidance on when to visit the vets, and advice on what you can do for your canine companion at home.

In this article, we will cover:

  • What causes diarrhoea in dogs?
  • Puppy diarrhoea
  • What can dog diarrhoea look like?
  • When should you contact your vet? 
  • How can you help your dog at home?
  • How can you prevent your dog from getting diarrhoea?


What can cause diarrhoea?

Diarrhoea happens because of damage and inflammation to the intestinal lining. Intestinal inflammation leads to an inability for the intestine to absorb water, meaning there is more water lost in the faeces causing diarrhoea.

As so many things can cause intestinal inflammation, diarrhoea can present in a number of different ways.

Causes of Acute Diarrhoea

Acute diarrhoea lasts less than one week and is self-limiting - meaning it usually resolves with time.


1. Dietary Indiscretion

Lots of dogs love to scavenge, it is their way of exploring the world through smell and taste. Sometimes however, they may eat something other than their usual food that doesn't agree with them and this can cause acute, self-limiting diarrhoea.

Dietary indiscretion is like food poisoning in people and is the most common cause of diarrhoea in dogs.


2. Obstruction

Any cause of obstruction in the guts can lead to diarrhoea. Most commonly, the culprit is a foreign body. If your dog likes to chew things or scavenge, a foreign body can be an annoyingly common occurrence.

Foreign bodies may pass on their own with normal bowel movements or can be more of a hassle to get out and require veterinary care. If you are worried about a foreign body be sure to contact your vet.


 3. Toxins 

Toxins are substances that are poisonous to your dog. Many different toxins can cause diarrhoea. Toxin ingestion is more common in younger dogs and scavengers. An example of a well-known toxic cause of diarrhoea in dogs is chocolate.

If you suspect toxin ingestion (for example an entire chocolate cake is suddenly missing), contact your vets immediately. Many of theses toxins have effects other than diarrhoea which could pose more of a risk to your dog.


4. Parasitic 

Parasitic infections are common causes of diarrhoea in young dogs and occur less frequently in adult dogs - as most receive preventative wormers.

Raw diets can increase the risk of a parasitic infection as raw meat can have a high parasite burden. If raw feeding, a frozen commercial diet and safe handling is the best bet to avoid unwanted guests in your dog's digestive system. 


5. Viral

Viral infections such as Canine Parvovirus and Canine Distemper Virus can cause diarrhoea in dogs. This is most commonly seen in puppies as most adult dogs are vaccinated against these diseases. Both can be life threatening and if suspected we recommend you seek veterinary advice immediately.

Canine parvovirus is often seen as large amounts of profuse, watery and sometimes bloody diarrhoea as well as vomiting and decreased appetite. Canine distemper virus is seen as a cough, diarrhoea, tremors and nasal discharge. 


6. Bacterial 

Diarrhoea can also be caused by bacterial infection of the gut. This can happen because of an overgrowth of an existing bacteria or a new, pathogenic bacteria setting up camp in your dog’s gut. Raw diets can increase the risk of bacterial enteritis as raw meat has a higher amount of bacteria such as E. coli and Salmonella. 

Contrary to popular belief, this is not a very common cause of diarrhoea as bacteria make up the normal environment of the gut. Therefore, in a majority of cases of diarrhoea your dog will not need antibiotic treatment. If anything, giving your dog antibiotics may worsen their condition as antibiotics will kill off the beneficial resident bacteria that keep the gut happy.


 7. Acute Haemorrhagic Diarrhoea Syndrome 

Acute Haemorrhagic Diarrhoea Syndrome (AHDS) is characterised as a sudden and severe bloody diarrhoea. The cause is currently unknown and it can cause life threatening dehydration. Early treatment is needed for AHDS with fluid therapy being the most effective treatment, so seeking veterinary advice is imperative.


8. Drug Reactions 

Another cause of acute diarrhoea is adverse effects to certain drugs. Most commonly diarrhoea is seen as a side effect of non-steroidal anti-inflammatory drugs (NSAIDs) or antibiotics and will stop when the treatment ends. If severe and prolonged, contact your vet for advice before stopping any treatment your dog is on.


9. Acute Inflammation/Infection outside of the Digestive Tract 

Inflammation within the abdomen but outside the intestinal tract can cause diarrhoea. Commonly there are other clinical signs associated with these conditions. Causes of diarrhoea outside of the gastrointestinal tract include:

  • Liver disease
  • Womb infections
  • Kidney infections
  • Pancreatic disease
  • Peritonitis

Diagnosis can be done by blood tests and diagnostic imaging conducted by your vets and the conditions can be treated accordingly.


10. Diarrhoea in Puppies 

Diarrhoea in puppies can happen for a few reasons. Bringing a new puppy home is an exciting time for everyone and your new family member will be going through an a lot of changes to their care and environment. 

Diarrhoea can occur as your puppy settles in to their new diet. Wanting to change diet from what your puppy was receiving in their old home is common. We all want our dogs to have the best and food makes up a big part of their day. However, sudden changes in diet are likely to trigger diarrhoea.

The risk of this can be reduced by gradually introducing new food and mixing it with the current diet - adding more and more until they've completely changed over. This allows your puppy's body to get used to the change, making a reaction to the food less likely. 

Puppies are notorious for eating things they shouldn't, making dietary intolerance and toxin ingestion - along with the resultant diarrhoea - an unfortunately common occurrence. As detailed above, if you suspect toxin ingestion in your puppy be sure to contact your vet. 

Another reason diarrhoea can occur in puppies is as a side effect of vaccinations. This can last a couple of days. This is because your dog's immune system is being challenged by the vaccines. All the focus is on building up immunity, making them more prone to diarrhoea due to this stress on the body. This shouldn't be anything to worry about and will resolve itself as your dog recovers from the vaccine.


Causes of Chronic Diarrhoea

Diarrhoea lasting for more than three weeks is called chronic diarrhoea. It may happen on and off or be continuous, and can present as mild diarrhoea or more severe.


1. Food Allergies

A food allergy is a common cause of chronic diarrhoea in dogs. It may occur with a change in diet or may develop over time without any change. It is usually in response to the type of protein. 

An exclusion diet or food trial is a relatively cheap and effective way of diagnosing food allergy. They are done by starting your dog on a control diet with a new protein source and slowly reintroducing their regular food. There are commercial diets which are pre-prepared for use in food trials to take the stress out of the process. Once you have identified the culprit causing your dog’s allergies, dietary management can be used to avoid the allergen and ensure your dog receives a more digestible diet.

Your vet will be able to advise you best on how to conduct an exclusion diet.


2. Inflammatory Bowel Disease 

Inflammatory bowel disease is a disease of unknown cause in dogs. It is different to inflammatory bowel syndrome which can cause diarrhoea in humans. IBD in dogs is related to a dysregulation of the dog's own immune system. 

Diagnosis is by blood tests and sampling of the gut by biopsy. This is done by the vet and treatment is with immune regulatory drugs.


3. Chronic Inflammation/Infection outside of the Digestive Tract

Long term inflammation in the abdomen but outside of the digestive tract can cause diarrhoea in dogs. Examples of causes of chronic diarrhoea outside of the digestive tract include: 

  • Pancreatic disease
  • Endocrine (Hormonal) disorders 
  • Kidney disease
  • Liver disease

These conditions can be diagnosed by blood tests done at your vets and treatment can be started accordingly. 


4. Cancer 

This can be a scary one to include on the list, but neoplasia (cancer) can cause diarrhoea in your dog. Please don't panic as diarrhoea does not instantly equal cancer and there is a long list of more common causes!

Cancers of the gut are uncommon in dogs. They are more frequently seen in older dogs; however, they can occur at any age. In addition to diarrhoea it usually presents with lethargy, inappetence, gradual weight loss and vomiting. 

Cancer can be diagnosed by your vets using imaging devices, running some blood tests and taking samples from the gut for analysis. Treatment and care for your dog can then be discussed according to what they have found.


What can Diarrhoea Look Like?

Now you know the long list of causes of diarrhoea we can talk about how to spot it. It might seem obvious, but diarrhoea has a number of different features that can give us more information. Colour, consistency, amount and frequency are the key ways of describing diarrhoea.

Although determining many of the causes will require further diagnostic tests, these features may guide us to the potential causes, severity and the best approach to helping our dog.

So, apologies if you are reading this on your lunch break because we are going to get descriptive!


A Quick Note on Normal

Identifying normal and abnormal poo can be quite challenging if you are a newer dog owner or if your dog has had chronic diarrhoea. The normal consistency of faeces is firm but not hard. The shape should be like a log with minimal segments. The expected colour is chocolate brown.

There are a number of poo charts/scales out there for dogs and if you are worried about your dog, you can always use the Felcana Symptom Checker to determine if your dog needs emergency veterinary advice. 


Red Streaks 

Red streaks in poo are fresh blood passing with faeces. This signifies bleeding in the lower digestive tract (the colon or rectum). The amount and frequency of fresh blood in the faeces gives us information on the severity of the bleeding.

Consistent and/or large amounts of bloody diarrhoea can show a greater haemorrhage that may be of more concern and we would recommend seeing your vet as soon as possible.


Black and Sticky 

Tar-like poo is called melena. It happens when there is bleeding in the upper part of the digestive tract. The blood gets digested and turns a dark colour and comes out with the faeces.

If you suspect your dog has melena you should contact your vets straight away as bleeding (haemorrhage) of the upper digestive tract needs investigating.


Fatty Stools 

A fatty, pale, yellow/grey appearance to your dog's poo may be indicative of pancreatic disease.

The pancreas produces enzymes to break down fat. When there is pancreatic disease, the fat doesn't get digested and passes through with the faeces - causing the change in colour and consistency.


Visible Worms

There are different types of parasites and not all of them are visible to the naked eye. Often, a stool sample needs to be taken and looked at by the vet under the microscope to determine what parasite is there. So, it is important to remember that just because you can't see any worms doesn't mean your dog hasn't got any!

Common squatters in your dog's poo and their appearances:

  • Hookworms - Very small and thin worms which are wider at one end than the other
  • Whipworms - Thread like white worms
  • Roundworms – Looks like spaghetti and can be several inches
  • Tapeworms - The egg sacs are seen instead of the actual worm. They look like grains of sand and may be seen stuck to your dog's bottom 
  • Protozoa such as Giardia and Coccidia are not visible to the naked eye 



Jelly-like diarrhoea containing mucous can be caused by many different things. Mucous is normally produced by the large intestine as a protective mechanism and intestinal disease can cause overproduction or loss of mucous in the faeces. 

When should you contact your vet?

Deciding when to take your dog to the vets about diarrhoea can be difficult. As discussed, acute cases of diarrhoea self-resolve and don't require any specific treatment. However, depending on the cause and how your dog presents they may require supportive care. A major part of supportive care is intravenous fluid therapy to overcome dehydration.

An easy way to determine if your dog requires emergency veterinary attention is by using our Felcana Symptom Checker. As some general guidelines, we recommend a visit to the vets as soon as possible if your dog has any of the following signs:

  • Lethargy
  • Dehydration 
    • Your dog may have a 'skin tent' which is where you pull the skin up to make a tent and it keeps its shape for longer than normal as it is less elastic
    • Your dog's eyes may look sunken 
  • Weight loss
  • Continuous vomiting 
  • Signs of severe abdominal pain 
    • This can be seen as changes to posture, vocalisation, difficulty getting up, a tense or swollen abdomen and an increased breathing rate because of the pain
  • Severe chronic diarrhoea 
  • Worsening diarrhoea 
  • Black, sticky poo 
  • Large amounts of fresh blood 
  • Continuous fresh blood 
  • You suspect toxin ingestion (a phone call to the vets should be sufficient to decide if your dog needs to go in for veterinary care)


Chronic diarrhoea in your dog should be investigated by the vets (but this is not likely to be an emergency unless severe.) This is so your dog can receive necessary treatments to make them more comfortable and manage any underlying conditions.

When you go to the vets it would be very helpful to let them know about the colour, consistency, frequency and amount - and nothing is more informative than a picture. If the diarrhoea is chronic, keeping a diary of how your dog’s poos have changed and any key events/meals that day can be invaluable!

Your vet is likely going to want to run some diagnostic tests such as analysing a stool sample, doing some blood tests and undertaking some imaging to allow them to determine the best treatment for your dog.


What can you do to help your dog at home? 

1. Feed your dog

The most important aspect of care for your dog with diarrhoea is continued feeding. There is an assumption that you should starve your dog, however food is imperative to getting the cells of the gut to heal.

We would recommend switching to a bland diet that is more easily digestible such as boiled chicken breast or white fish and rice.


2. Provide plenty of water

As diarrhoea is caused by a loss of water in the intestines, your dog can become dehydrated quite quickly. This is especially the case in older dogs and puppies due to their decreased ability to retain water. If your dog seems reluctant to drink (which might be because they are feeling poorly), you can add water to their food to increase their intake.


3. Kaolin

Kaolin is a clay that acts to absorb some of the water in your dog's poo allowing them to pass firmer faeces.


4. Probiotics

Probiotics have varying amounts of supportive evidence. Many owners report a good response and the general consensus is that there is no harm in giving it a go, as probiotic bacteria is extremely unlikely to cause any adverse effects to your dog.


5. Exercise your dog if they want to 

Your dog can still go for walks if they want to, especially if the diarrhoea is mild and they don't seem lethargic or dehydrated. Just make sure you take some poo bags and a bottle of water to clean up after them and stay on the good side of your neighbours!


How can you prevent your dog getting diarrhoea? 

It is almost inevitable that your dog will experience diarrhoea at some point in their lives and many of the causes are unavoidable. However, there are things you can do to reduce the occurrence.

Maintaining a healthy lifestyle for your dog and keeping up to date with preventative veterinary care is your best bet for reducing diarrhoea.

Routine worming with a prescription product can prevent parasitic infections and keeping up to date with your dog's vaccination can prevent diarrhoea due to viral infection.

If possible, discouraging scavenging (we know this is not always easy) and keeping your dog away from toxins can also reduce the chances of dietary indiscretion. Ways to do this can include walking your dog on a tighter lead and keeping foods that are toxic to dogs out of their reach.


Remember Diarrhoea isn't always Something to Worry About!

As discussed not all diarrhoea is the same and it is a very common thing to happen in dogs. Remember not to panic if you think your dog has diarrhoea. Follow the steps above to help them out as much as possible from home and seek veterinary advice as indicated. Finally, make sure your dog doesn't need emergency care by using our Felcana Symptom Checker.


Has your dog had a case of the tummy upsets before? Let us know in the comments below! 


This article was written by Sumuduni Theminimulle. Sumuduni is a final year vet student at the University of Bristol. She is set to graduate in 2022 and start her first role as a small animal vet in Essex.