Vet Panel: Dogs and puppies with diarrhoea


Digestive upsets are a really common condition in dogs and puppies. So we’ve gathered a vet panel of our regular writers to talk about it for you! They are vets David Harris (DLH), Laura Waring (LW) and  Rachel Kenvyn (RK) and final year vet student Joe Dunne (JD).

JD Oh, and please finish your lunch before reading this article, as today we are talking about the unpleasant topic of dog diarrhoea. 

So, to start us off – 

What is diarrhoea?

LW Diarrhoea is the frequent passing of soft faeces, which can be troublesome.

JD Diarrhoea is actually more complex than you may think – if your dog passes larger poos or does them more often than normal, he has diarrhoea. Diarrhoea is not necessarily watery (though it definitely can be), so you can be forgiven for not noticing if your dog has mild diarrhoea that appears normal! It is a good idea to know roughly how often and how much your dog normally goes to the toilet, so you can spot a problem even if the stools themselves look normal. 

DH Exactly. The signs can be really obvious, or pretty subtle. But it all boils down to an increase in either faecal frequency or volume (or, of course, both).

Are there different types of diarrhoea?

JD We generally class diarrhoea as being small intestinal or large intestinal, based on where we think the problem originates. Small intestinal diarrhoea is more commonly watery and of increased volume than large intestinal, can vary in colour from normal to black, and can cause increased gassiness, stomach discomfort and vomiting. Large intestinal diarrhoea can look normal too, or can have fresh blood in it, causes straining when defecating, is passed more frequently and can look mucousy. However there is a lot of overlap between these two categories, and both can even occur at the same time. 

We also like to know how long the problem has been going on for – diarrhoea that lasts for less than 24-48 hours is considered acute, while diarrhoea that lasts longer than this is chronic, often causing weight loss.

DH The classification into “large bowel” and “small bowel” can be really useful for us to help diagnose the problem. But often, the timing is even more important. Most diarrhoea that we see in practice is acute (short duration), and that’s usually fairly easily managed. But chronic or ongoing diarrhoea doesn’t respond to the same approaches, and so may need different management and more diagnostic tools.

What is the most common cause of diarrhoea in dogs and puppies?

JD By far the most common cause of acute diarrhoea in both dogs (and humans) is a dietary indiscretion. Sometimes, something doesn’t agree with your dog’s stomach and it causes diarrhoea. 

DH This is sometimes called “garbage gut”! Dogs are scavengers and eat all sorts of nasty things. This can of course be the case in any dog, but seems most common in young adults and puppies.

LW Puppies by nature are inquisitive and playful, this can sometimes lead them to trouble. Eating food they wouldn’t normally or consuming something they find out in the garden or on a walk may lead to diarrhoea. Some plants or bulbs are toxic to dogs, so if you are concerned that your pet may have eaten something dangerous please consult your vet. Occasionally puppies will chew or even swallow non food items such as material or plastic. If you find evidence this has happened or see your puppy swallow something it shouldn’t have again seek urgent veterinary attention from your practice. 

DH That’s a good point about toxins and non-food items.

JD Some substances or foods can be toxic or covered in bacteria, and cause diarrhoea. Some dogs may be allergic to something that does the same. Try and prevent your dog scavenging, change their diets gradually, and prevent them getting close to substances you know are toxic.

DH This would also include rapid changes in diet.

JD It takes time for your dog’s gut bacteria to adjust to changes in diet, so if they eat something they are not used to or you change their diet suddenly, it can cause diarrhoea. They will generally not be unwell and have no other signs. These bouts of diarrhoea usually pass once the unusual food has also ‘passed’. 

LW Sudden changes in diet are common when puppies go to their new homes. This change in food can sometimes lead to digestive upsets. When you bring your new puppy home it is best to slowly transition them onto the food you intend to feed them over a period of at least a week. Ask the breeder for a supply of change over food so that you can gradually mix in more of the puppy’s new food. Slowly changing over the diet should lessen the chances of the change in diet causing a bout of diarrhoea.

Do parasites often cause diarrhoea?

JD Intestinal parasites are a common cause of acute diarrhoea, particularly in young puppies… 

LW Especially roundworms. These can be transmitted to the pup before it is even born if the mother is carrying the parasite. Unclean or unhygienic conditions can harbour parasites, so it is important to check out the environment where your puppy is being reared. Careful selection of a reputable breeder will reduce the chance of acquiring a puppy with a large parasite burden. 

JD Worming appropriately should prevent worms, so will only be a potential cause in dogs that are not wormed. There are far too many kinds of worms to discuss here, so instead be on the lookout for signs such as poor weight gain and a pot-bellied appearance in puppies, some vomiting, scooting on the floor or licking around the anus, seeing visible worms or eggs in faeces and being generally unwell. Some more serious worms can cause severe weight loss, anaemia, respiratory issues and other problems. Please keep your puppies in a clean environment until they are old enough to be wormed and then regularly worm them from that point onwards.

DH Yes, and this is an easy thing to control. In older dogs, though, I think worms are less likely to be the underlying cause of a sudden-onset – acute – diarrhoea. It definitely can happen, but I wouldn’t say it’s at the top of the list.

What infections can cause dogs to get diarrhoea?

JD There are a number of bacteria and viruses that can cause acute diarrhoea, particularly in young puppies or dogs that are immunocompromised (such as pregnant dogs or those on chemotherapy). Infectious diarrhoea is more common in large groups of dogs, in kennels or at breeders. Raw dieting, or food that is unclean can also cause infections. 

DH Yes, there have been a number of cases reported of Salmonella and Campylobacter infections associated with a raw diet. Although it can happen in cooked diets, the risk seems to be higher in raw food. Although most dogs tolerate these bacteria better than humans do.

JD Many of these infections are not too serious, and pass with time and symptomatic treatment, but it is important to note that some of these pathogens can infect humans too – always practise strict hygiene around a dog with diarrhoea.

LW Infectious diarrhoea is often more serious and may cause other symptoms other than the diarrhoea. Potentially infectious causes of diarrhoea range from bacterial infections to viral causes such as parvovirus. 

JD This nasty virus causes severe smelly and bloody diarrhoea, vomiting, dehydration, blood disorders and even death if not treated. It is mostly seen in puppies, as older dogs are vaccinated for this. Dogs with parvovirus usually need extensive treatment at your vets. A less severe disease called haemorrhagic gastroenteritis also causes bloody diarrhoea – it can be hard to differentiate between this and parvovirus, so please take any puppy with bloody diarrhoea to your vet.

DH We tend to think of Parvo as being an issue for puppies, of course, but any dog can become infected. It’s just that puppies are usually much more severely affected.

LW Puppies are more susceptible to infections because their immune systems are still developing. Some infections (like parvovirus) can be prevented by vaccinating the mother and the puppies. It remains the case that taking care to buy your puppy from a legitimate and reputable source will lessen the chances of your new friend coming to you with a problem. 

DH The better the mother’s immunity to Parvo, the longer the window you’ve got, as she’ll pass on those antibodies to her pups. But sooner or later, they “wane”, or wear off. This is the danger moment – and that’s why we like to begin vaccination relatively early, to try and get protection on board as soon as possible.

JD All patients should also ensure they keep on top of their vaccination and worming protocols, to prevent secondary issues.

What else can cause diarrhoea?

JD There are many other less common causes of acute diarrhoea including: foreign bodies; intestinal twisting or telescoping; liver disease; pancreatitis; Addison’s disease; drugs like antibiotics or NSAIDs; peritonitis; pyometra; or even some cancers. Sometimes we may never find out the cause, and the diarrhoea passes without an issue. 

DH A good point about medicines – diarrhoea is a really common “non-specific” side effect to a wide range of medications. With drugs like anti-inflammatories it can be pretty serious too.

LW Stress. When a puppy leaves its mother and siblings to join a new household there is inevitably some degree of stress involved. As new owners we can try to lessen this by not overwhelming the puppy with visitors, allowing it to settle in and providing it a safe quiet corner to retreat to and rest. However, it is possible that stress can impact upon the digestive system and cause diarrhoea. 

What about chronic diarrhoea?

JD Chronic diarrhoea is diarrhoea that lasts longer than 2 days. Almost all causes of acute diarrhoea can progress to chronic, so these are usually ruled in or out first.

DH Although in my experience there’s often some underlying issue that has meant that they haven’t bounced back the way we’d expect. Of course, there are a range of conditions that almost always cause chronic rather than acute problems.

JD Food intolerance and allergies can cause chronic diarrhoea.

DH Yes – food allergies in dogs normally cause itchy skin, but they can cause diarrhoea sometimes. Intolerances – like lactose intolerance – can do the same. 

JD After ruling out acute diarrhoea that has progressed to chronic, vets may recommend switching to a novel food (one your dog has never had before). Diet trials can be tricky and time-consuming to get right, and you have to be very strict when feeding your dog, as well as being prepared that it may not work. Sometimes multiple different diets are needed before you find one suitable for your dog. During or after diet trials, your vet may also give antibiotics, as certain ones can treat chronic diarrhoea.

DH This is often due to a condition called “”SIBO”, or small intestinal bacterial overgrowth. This is often linked to EPI (Exocrine pancreatic insufficiency), where the dog isn’t able to digest fats normally. It’s most common in German Shepherds, but can occur in any dog, as can the inflammatory bowel diseases.

JD Sometimes your dog’s body is its own worst enemy, and their immune system is causing chronic diarrhoea – irritable/inflammatory bowel disease is an example where this is the case. Most of these dogs will be middle aged. Cases like these can be hard to diagnose, and are often caught by accident. If food trials and antibiotics fail, steroids are often given for chronic diarrhoea, and some dogs improve on them. Long-term steroid use carries its own problems, so your vet will need to weigh up the positive and negative effects of this.

DH I think we published a blog on this a while back…

JD Other uncommon causes of chronic diarrhoea include protein-losing diarrhoeas, pancreatic insufficiency, or cancer. Unfortunately, we sometimes cannot identify an obvious cause, so must treat chronic diarrhoea symptomatically, as described above. Regular check-ups are essential in determining if treatment needs to change, and to check you and your dog are happy. Further advanced testing via blood results, imaging, endoscopy or biopsies can lead to a diagnosis, but this is not guaranteed.

When do I need to call the vet?

LW Firstly, check that your puppy is otherwise well. If the puppy is bright, continuing to eat and drink and be playful there is no immediate cause for concern.

RK There are many things that you can do at home to support your dog’s gastrointestinal system and speed up their recovery when they are suffering from diarrhoea. Diarrhoea is often short-lasting however it is important to contact your veterinarian if your dog has had diarrhoea for more than 24 hours or if they are poorly, not eating or displaying other symptoms such as vomiting or retching.

LW If they are showing any of the following signs or symptoms it is best to get them checked by the vet:

  • Vomiting
  • Lethargy
  • Not eating or drinking
  • Blood in the faeces
  • Dark tar like stools
  • Foul smelling diarrhoea 
  • Obvious signs of parasites
  • Diarrhoea which is persisting beyond 48hours

DH I always get a bit concerned about a dog with diarrhoea AND something else, as it suggests there might be something more serious going on. Especially in old or sick dogs and puppies. 

LW Puppies are less resilient than adult dogs and may become seriously unwell quickly. If in any doubt about the condition of your puppy it would always be safest to arrange a check up with your vet. 

How do vets determine what the cause is?

JD Every patient is different, and every vet approaches each case in a different way, so the following is only one way your vet may investigate your dog with acute diarrhoea.

First, they will ask the history, to determine if there is an obvious cause, such as food intolerance or parasites – photos of diarrhoea, though unpleasant, can be a great help here. 

DH This is one of the less glamorous parts of the job! But I agree, it can be very helpful. It’s also something we can do over a video link, which is really important right now with periodic lockdowns.

JD Next they perform a clinical exam of your dog, assessing their heart and respiratory rates, weight, hydration status, general health, feeling their abdomen, assessing pain and possibly performing a digital rectal palpation. Sometimes, the vet may feel it is safe to treat the diarrhoea symptomatically and do no further tests.

If they are concerned there is another issue, they may wish to take blood, urine or even faeces from your dog to run tests or identify pathogens. They may also wish to perform an ultrasound or x-ray of your dog’s abdomen. Most cases of acute diarrhoea can be diagnosed or treated in this way, and it is rare to perform further tests.

RK Your vet may recommend performing faecal testing if they are suspicious of infection or parasite or if the dog’s condition has not improved using the above recommendations. A 3-day pooled faecal sample is usually required. A 3-day pooled faecal sample involves collecting a daily sample of faeces for 3 consecutive days to enable detection of pathogens that are intermittently shed. Faecal testing is often required as the treatment for a particular parasite or bacterial infection varies greatly depending on the cause. 

DH With chronic diarrhoea, we’ll start the same way, to rule out acute causes that haven’t resolved yet, but then we’ll normally try to narrow down the determine if there’s an underlying disease process.

JD Vets will often approach chronic diarrhoea step-by-step, ruling out causes as they go, as described above.

What is the best treatment for diarrhoea in dogs?

JD Treatment for acute diarrhoea varies depending on the cause and how well your dog is. Mild cases may simply require rest, time, bland food and anti-motility drugs. Others may need antibiotics, prokinetic drugs, adsorbents or fluids. 

RK In cases where your dog is bright, eating and not vomiting, the following adjustments can be made to help them at home – 24 hour fast, bland diet, feed little and often, keep hydrated, and rest.

DH The 24 hour fast is a bit of a controversial issue!

RK Not feeding your dog for 24 hours allows their gut to rest and recover. This is not suitable for all patients and especially not puppies, patients that are old or poorly. 

DH It can be very effective at stopping diarrhoea, but the gut cells get most of their nutrition directly from the food, so a prolonged starve can be a problem.

RK It is best to speak to your veterinarian to see if this is an appropriate option for your pet. In some cases, your vet may recommend feeding through the diarrhoea with a bland diet.

LW If your puppy is very well otherwise, then changing them onto a very bland diet can often help to settle innocent causes of diarrhoea. Boiled rice and plain boiled chicken are easily digested and often readily accepted. Feed this in place of your puppy’s usual feed. 

DH Yes, the bland diet I think is the key. Although there’s relatively little solid science behind why it works, it definitely does!

RK A bland diet is one that is easily digestible and unlikely to further upset your dog’s gastrointestinal system. Normal dog diets may be too ‘rich’ for them while they are suffering from diarrhoea. Feeding a bland diet will not only help speed up your dog’s recovery from the diarrhoea but will also provide essential nutrition to them during their illness. Your vet may recommend a prescription diet that is formulated specifically for diarrhoea which contains high fibre, electrolytes and vitamins. Alternatively, plain boiled chicken (no bones or skin) and rice may be prepared at home. However, it may be more difficult to estimate your dog’s calorie and nutritional requirements using the home-cooking approach.  

LW This can be done until the faeces are firm and normal, when normal feeding can be resumed. 

RK Once your dog’s diarrhoea has resolved, it is advisable to continue feeding a bland diet for a couple more days. This will hopefully prevent relapse in your dog’s diarrhoea when you start feeding their normal diet again. It is also helpful to gradually reintroduce their normal diet over 3-4 days. This can be done by feeding 25% normal diet, 75% bland diet on day 1, 50% normal diet and 50% bland diet on day 2, 75% normal diet and 25% bland diet on day 3 and then 100% normal diet on day 4. 

DH I quite like using a probiotic mix as well.

RK These are products that contain ‘friendly bacteria’ and binding agents, often as a syringe, to feed to dogs and speed up their recovery from diarrhoea. The addition of probiotics is thought to support the natural balance of bacteria within the gastrointestinal tract which is often disrupted when your dog has diarrhoea. These products are often flavoured to ensure palatability. Binding agents such as kaolin (clay) are also added to probiotic supplements to resolve the diarrhoea quickly. 

DH And many have prebiotics in too – particular ingredients to promote the growth of good bacteria and suppress bad ones.

LW However, if changing to a bland diet has not improved the situation, and diarrhoea is persisting beyond 48hours it would be best to get the puppy checked by your vet. If the puppy is developing other symptoms alongside the diarrhoea it would also be important to seek advice from your vet. 

DH It’s important to not to overload their stomachs, I think, as it often makes it worse.

RK Feeding little and often prevents your dog’s gastrointestinal system from becoming ‘overloaded’. Feeding little amounts, more frequently throughout the day is less likely to contribute to the diarrhoea and more likely to allow your pet to digest and obtain the nutrients from the food that is being fed. Feeding large meals, less frequently is also more likely to make your pet feel nauseous. 

DH The other absolutely key thing is to maintain their hydration levels. The most dangerous thing about diarrhoea is that it can cause dehydration – potentially very fast.

RK While your dog has diarrhoea, they are more likely to become dehydrated and lose electrolytes. It is important to ensure your dog is getting plenty of fluids. Increasing your dog’s fluid intake can easily be achieved by adding water to their food. Feeding a wet gastrointestinal diet will have a higher water content than dry food and is an easy way of increasing your pet’s water intake. Ask your vet about electrolyte solutions that are available and whether this option is appropriate for your pet. If your dog is not eating or drinking, then it is advisable to contact your vet as it may be necessary to administer fluids through a drip if they become dehydrated.

Resting is important too – don’t exercise your dog too hard when they have diarrhoea. Exercising your dog while they have diarrhoea is only likely to worsen the diarrhoea, as exercise increases gut motility and thus food moves more quickly through the gastrointestinal tract. Let your dog rest when they have diarrhoea, as this will allow a quicker recovery process.

DH Sometimes, of course, we need more aggressive treatment, such as steroids or occasionally antibiotics.

RK Antibiotics are rarely required for treating diarrhoea in dogs. Most cases of diarrhoea are self-limiting, meaning it gets better on its own within a couple of days. Certain conditions, such as bacterial infections, parasites, colitis (inflammation of the colon) do require a course of antibiotics. 

JD It will really depend on what the vet diagnoses. Some treatments do not work at first, and require multiple vet visits – do not worry, as acute diarrhoea is rarely life-threatening.

Bottom line?

DH That was an awful pun! But I’d say that the majority of diarrhoea cases are self-limiting, and are due to eating something nasty. With care and appropriate treatment – either at home or from the vet if it doesn’t settle pretty soon on its own – most dogs make a good recovery in a couple of days.

JD Diarrhoea is far from pleasant, so knowing your dog’s normal toileting routine will help you spot when something is amiss; this will give your vet more information to help diagnose the cause and come up with the best treatment plan to get your pup back to normal.RK Diarrhoea is a common condition and your pet will likely suffer from this condition at least once in their lifetime. It is typically self-limiting and recovery from diarrhoea can be hastened by feeding a bland diet and feeding this little and often. It is important to contact your veterinarian if your pet is well but has had diarrhoea for more than 48 hours or if your pet has diarrhoea and is poorly and displaying other symptoms such as vomiting and lethargy.

Remember, if you do suspect your dog may have eaten something it shouldn’t check our Poisons Guide.

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