Dealing with diarrhea

Diarrhoea occurs when food travels too quickly through the intestine, and water and nutrients are not properly extracted from the stool. The following all come under the same broad category of diarrhoea:

  • Stools passed more frequently than normal. As a general guideline, dogs will usually pass faeces as many times per day as they are fed +/-.

  • Stools that are normal first thing in the day but become progressively looser as the day goes on.

  • Stools that are perhaps not loose as such, but softer than they should be / more voluminous than normal.

  • Stools which are sporadically loose (there are several nasty bugs that typically manifest in on / off periods of diarrhoea, and food sensitivities may also result in periods of normal stools or even constipation, alternating with looseness).

  • Unusually coloured stools.

  • Stools which are smellier than normal (the waste products of bacteria are particularly malodorous; hence this is common in cases of gut infection).
Why does the problem need addressing?

Loose stools are unpleasant, difficult to clean up and unhygienic. Although your dog may appear to be outwardly healthy, the longer-term consequences can be serious. Untreated diarrhoea can result in:

  • An imbalance of electrolytes and dehydration (puppies and senior dogs are especially vulnerable).

  • Depleted levels of the friendly gut bacteria needed for efficient digestion. 

  • Loss of weight, condition and energy due to nutrients not being digested, absorbed and metabolised to their full potential. Over time, this may result in nutrient deficiencies.

  • A dog that is more vulnerable to other illnesses due to immune stress. 

  •  Impacted anal glands. If the stools are not well-formed, then the natural emptying mechanism may fail.
When to call the vet

If your dog suffers from mild symptoms, remains outwardly well, is energetic and has a good appetite; careful dietary management may be the solution.

Many bouts of diarrhoea will clear up after a few days. However, there are times when a veterinary examination is warranted. These include:

  • Puppies and very elderly dogs - due to their greatly increased susceptibility to dehydration.  

  • An acute and dramatic onset of diarrhoea.  

  • Prolonged diarrhoea where dietary management has failed to help.

  • Cases where other symptoms are present, particularly vomiting.

  • Your dog appears unwell and is lethargic, inappetent, and / or showing signs of pain (e.g. vocalising more than usual, breathing more quickly). A “praying” position which looks a little like a play-bow is typical of pancreatic problem which warrant immediate treatment.

  • Yellow, grey or pale stools. Sometimes this is because the stool is travelling too quickly through the gastrointestinal tract to pick up bile (which gives it a normal brown colour), but it may also be indicative of a pancreatic or liver problem, so it is best to err on the side of caution.

  • Greenish stools. This may be due to ingesting chlorophyll (from eating grass or other plants) but other possible causes are toxins, intestinal parasites (especially Giardia) or any condition affecting the gut where bile isn’t being recycled.

  • Bright red blood in the stool, which is a typical symptom of a dog with colitis (inflammation of the large bowel). Mucous may also be visible. Copious amounts of red blood could indicate an obstruction in the lower part of the digestive tract, and therefore all bleeding should be investigated.

  • Black, “tarry” looking stools which are caused by dark blood (malaena); this indicates bleeding from higher up within the digestive tract and is a serious problem which requires immediate veterinary intervention.

  • You suspect your dog may have eaten or drunk something he / she shouldn’t have e.g. stools, toxic foods or plants, garbage, pond water.

  • Bacterial / viral infections are known to be doing the rounds.
Diagnosing the problem

The vet will initially palpate your dog’s abdomen and take his / her temperature. In cases of severe or long-term diarrhoea, it’s wise to be prepared with a stool sample. Faecal analysis is a useful way to identify or rule out pathogenic causes. Other diagnostic techniques might include blood tests, endoscopy, sonography or gut biopsies. Faecal and blood samples are relatively easy to obtain, so your vet will often carry out these less-invasive procedures first, and if necessary, undertake more complex investigations later to establish a definitive diagnosis.

Food trials are a useful way to determine dietary sensitivities, and the results are often more accurate than allergy testing (especially when food intolerances – where the immune system isn’t directly involved – are suspected, since these will not show up on an antibody test).

Faecal testing

A 3-day pooled sample, as the name suggests, is faeces collected over 3 days and placed into the same sterile container. This can increase the laboratory’s chance of finding pathogens (which can be difficult to pick up on a single sample if they are being intermittently shed). The stools should ideally be collected on consecutive days, but in cases of sporadic diarrhoea, they can be collected for up to a week enabling more time to select 3 samples of loose stools rather than a mixture of loose and formed ones. If the sample is drying out, you can add a couple of drops of cooled boiled water to keep it moist. It should be kept in a cool place (but not in the fridge).

Potential causes of diarrhoea


Weigh your dog and weigh the food to ensure the correct daily volume is being fed. A small reduction may resolve the problem if you are feeding a little too much. Don’t forget to factor in any other foods given in addition to the main diet as these supply calories too. Dogs may be supplementing their menu by scavenging on walks, so keep them on the lead if this is something that is suspected and their recall needs work. Whilst free feeding suits some dogs who like to graze, measured portions 2-3 times per day may be more appropriate if your dog is prone to eating too much in any one sitting and / or has no daily limit on the quantity of food available. 

Sudden change of diet

Changing over to a new diet too quickly, without giving the dog’s digestion sufficient opportunity to adapt to the new ingredients or nutrient balance can cause diarrhoea. Revert to a food that is known to agree with your dog. Once things have settled down, try reintroducing the new diet gradually over the course of 7-10 days. New treats or additions to the main diet can also be provocative, so offer them in tiny quantities until you know how well-tolerated they are. Only offer one new food at a time so that it is easier to identify the culprit if there is a problem. Monitor your dog to check whether he or she is helping him or herself to items which could be causing an upset, and keep an eye on what other members of the household are feeding too if applicable. 

Stress, anxiety & over-excitement

When a dog’s fight or flight mechanism kicks in, extra stomach acid and digestive juices are produced and stomach muscle tension increases in order to quickly digest and eliminate food in the digestive system. This helps to prepare the body for immediate action, but can result in loose stools. Our tips for anxious dogs fact sheet may be of help if you suspect this is causing or contributing to diarrhoea. 

Change of water source

This is a more common problem in puppies, but can affect adult dogs too. It’s certainly worth considering if you have just acquired your dog or puppy or moved recently. Change to filtered water and gradually start introducing tap water once the symptoms have completely abated. If the symptoms come back back when tap water is reintroduced, you may need to give filtered water indefinitely. Ingestion of seawater and contaminated pond / puddle water can cause more serious problems and it is recommended that you seek veterinary advice if this is suspected.

Infectious causes may include:

  • Bacterial infection such as Campylobacter and Salmonella.

  • Viral infection such as Parvovirus.

Parasitic causes may include:

  • Worm infestation such as roundworm and tapeworm.

  • Protozoal parasites such as Giardia and Isospora.  

Other causes may include:

  • Intoxication.

  • Conditions of the pancreas - exocrine pancreatic insufficiency (EPI) or pancreatitis. 

  • Intestinal foreign body causing an obstruction. 

  • Neoplasia (cancer). 

  • Intussusception (where one segment of intestine "telescopes" inside another, causing an obstruction).

  • Secondary to liver or kidney disease. 

  • Adverse food reactions (allergies and intolerances to various foods / ingredients).
Managing the problem - general tips
  1. Restrict exercise to the garden so that you can monitor faecal output during recovery (as well as minimise the risk of passing on a contagious disease to other dogs or even people if the cause is infectious). Severe diarrhoea is also very difficult to clean up, so it's best to only allow your dog access to outdoor areas you can hose down and disinfect easily. You may want to limit access indoors to areas with hard flooring rather than carpets. 

  2. Try to identify and treat / address the cause of diarrhoea rather than simply manage the symptoms. This may help prevent recurrences. Be aware that conditions such as colitis and inflammatory bowel disease are syndromes rather than diseases (despite the name of the latter), and successful management may vary depending on what triggered the chronic intestinal inflammation. Food allergies can cause IBD for example. If your dog’s diarrhoea is symptomatic of a medical condition such as pancreatitis or renal disease, these conditions require special nutritional management under veterinary supervision.

  3. Osmotic diarrhoea (where water is drawn into the gut as a result of too many solutes remaining in the intestine) is common in simple conditions such as over-feeding or ingestion of any poorly absorbed substrate. It usually resolves without treatment in one to two days if food is withheld for a short time. Omitting one meal is usually sufficient, providing the volume is suitable when food is reintroduced, and indigestible foods are off the menu in future. Indigestible chews such as rawhide can cause or exacerbate diarrhoea (and they can also trigger allergic responses as a result of residual antigenic proteins and large polypeptide molecules that take a long time to excrete).  Don’t withhold food for longer than 12 hours unless your vet has advised otherwise. Although the traditional approach of starving for 24 hours gives the digestive tract some resting time, studies indicate that recovery is generally quicker if you continue to offer food (providing it is highly digestible and fed in small quantities – please see Recovery Diets below) [Case, 2011].

  4.  Increasing the frequency of feeds means smaller meals (which are often more acceptable to dogs with a low appetite) and less work for the gut to do at any one time. 3-4 Small meals are usually suitable during recovery (taking care not to exercise too near to a feed).

  5. Fresh water must always be available. Try to encourage drinking because dogs with diarrhoea are at risk of dehydration. Your vet may recommend an electrolyte solution to add to the water. Filtered water may be more appealing than water straight from the tap, and make sure it is not too cold.
Recovery diets

Options may include:

  • A veterinary diet formulated specifically for gastrointestinal conditions.

  • A highly digestible regular wet dog food which is not overly high in fat - ideally 4% max (as fed).

  • Home-prepared food.
Home cooking - preparation

Plain, steamed or baked white fish (which is very digestible and lower in fat than oily fish such as sardines and salmon) and a small quantity of well cooked, boiled, mashed potato (softened with the fish cooking liquor not milk/butter) are usually well-tolerated (unless your dog is known or suspected to be sensitive to either ingredient). Examples of white fish species include haddock, whiting, pollock and cod. If your dog does not like or tolerate fish, alternative protein sources may include skinless minced chicken or turkey, scrambled egg, rabbit or venison. 

Alternative carbohydrate sources may include well-cooked rice or sweet potato. A protein to carbohydrate ratio of approximately 2-3:1 is usually suitable for dogs (in other words, prepare two to three times more of your chosen protein source than your chosen carbohydrate source). Make sure the ingredients are well mixed to prevent clever dogs from selective eating.

Well-cooked and cooled rice and potato are both good sources of resistant starches. These feed the friendly gut flora which then convert the starches into short-chain fatty acids including a type called butyrate - the main fuel for the colonocyte cells that line the gut. Butyrate helps them to function properly and reduces inflammation within the large bowel.

Treats and extras are usually best withheld whilst feeding a recovery diet.

Home cooking - quantities

If your dog normally eats wet food, and you are happy with his or her weight, you can use a similar daily volume of home-cooked food.

For dogs who usually eat dry food, as a very general guide, you will need to feed approximately 3 times more than the volume of dry normally fed, since the home-prepared food supplies about a third of the amount of calories as an average commercial kibble.  The home-prepared fish and potato (at a ratio of 2.5:1) supplies @1.24 kcals/gram. The quantity may need adjustment depending on individual needs, but it should provide a reasonable starting point.

Don’t be tempted to over-feed, even if you have concerns about weight loss. Too much food can exacerbate diarrhoea, and your dog won’t be able to glean the full benefit of the nutrients in his / her food all the time the stools are loose. It may therefore be beneficial in the short-term to provide smaller volumes that the sensitive gut can handle than larger volumes which it may struggle with. Once the stools are firming up, quantities may then slowly be increased. Feeding little and often is usually better accepted and tolerated than trying to incorporate too much into less frequent, larger meals.

Home cooking – time scale

The home-prepared menu outlined above is only designed to be fed in the short-term (maximum 5 days plus up to 7 days transitioning back to regular food) as it is not complete and balanced. A veterinary diet or low residue, complete wet or fresh commercial product such as the Arden Grange Partners Sensitive canned food is recommended for dogs requiring a longer period on a recovery diet.

Getting back to normal

If your dog’s stools are firming up nicely on the home-cooked diet, the usual food can then be gradually phased back in over 3-7 days depending on how severe the symptoms have been (unless an alternative diet is necessary to help manage food sensitivities, for example). Kibble may be better digested initially if it is fed soaked (providing the manufacturer deems it safe to do so). The Arden Grange canine dry products can all be soaked, although as with wet food, it is important to pick up and discard any uneaten food promptly to avoid it attracting flies or drying out into an unpalatable, sticky consistency.

When soaking Arden Grange products, we advise using hot water (from the kettle, but not at boiling point) to cover the kibble. Leave to steep under a clean tea towel for about ½ hr prior to serving. More water can be added if a looser consistency is preferred. Check the food is not too hot nor too cold.

Little digestion happens before the food reaches the stomach because dogs are not designed for chewing, and unlike people do not possess salivary amylase. Softening and moistening the food can ease the initial workload of the digestive fluids and enzymes which may take some time to get back to normal after an upset. This may also help to increase your dog’s fluid intake, which can be especially beneficial if he or she is not drinking very much.

If you like to offer treats, don’t start reintroducing them until the digestion has completely recovered (i.e. not before a period of 7-10 days of normal stools) because if there is a setback soon after reverting to your chosen long-term diet it can be hard to know whether the food or the extras are responsible (or something else). For the same reason, it’s sensible to stick to one type of dog food until you are sure everything has settled down.

Adverse food reactions

There is no one specific course of action for a dog with a food allergy or intolerance because different dogs can be sensitive to different ingredients. A summary of general tips follows, but for a more in depth look at this complex subject, please read our adverse food reactions fact sheet. 

1. Consult your vet (especially if symptoms are acute) to rule out other causes and obtain treatment if necessary.

2. If your dog is eating some of the more common ingredients or foods responsible for adverse food reactions), you may like to try eliminating them first by means of a hypoallergenic diet such as Arden Grange. Arden Grange recipes do not include:

  • Wheat – some sensitive animals cannot tolerate gluten (which is also found in oats, barley, rye and unspecified cereal blends).

  • Beef – there is nothing inherently wrong with feeding beef, but some dogs do not find it as digestible as other meats. High digestibility is important because this avoids large antigenic (potentially reactive) protein molecules lingering in the body.

  • Soya (unless hydrolysed*) – some sensitive animals are reactive to certain tree pollens which are similar in structure to a specific soya protein. Therefore, the immune cells responding to the pollen can sometimes also take a dislike to soya.

  • Dairy products – some sensitive dogs are allergic to casein (milk protein), and many are lactose (milk sugar) intolerant because the ability to digest it is largely diminished when puppies grow up.

  • Unspecified ingredients – it can be difficult, if not impossible, to identify what comprises them, sources may vary depending on availability/price, and they may be of lower quality/digestibility.

  • Hydrolysed: A process which breaks down the protein into tiny fractions of a very low molecular weight that are too small to annoy the immune system, rendering the ingredient non-allergenic. Hydrolysis also “pre-digests” the protein, making it easy for the digestive system to handle.

3. Even if your dog has eaten particular foods in the past without adverse effects, it doesn’t mean they’re not provocative now. Unfortunately, dogs can develop an allergy to any dietary protein (unless hydrolysed), or intolerance to any ingredient over time. If you are already using a hypoallergenic diet without success, the next step is to consider either: -

  • A product with a novel protein (and also ideally a novel carbohydrate) source (i.e. ones that your dog has not eaten as dietary staples in the past). If for example your dog is currently fed on a poultry and rice-based diet, Arden Grange Sensitive (made primarily from white fish and potato) could be a good option.

  • An anallergenic veterinary diet. These products may be particularly useful for dogs who have eaten a wide variety of foods making it difficult to source a regular diet with novel ingredients. Anallergenic products include only hydrolysed proteins, and the better options use carbohydrate ingredients that have had their storage proteins extracted rendering those non-allergenic too. (Please note that Arden Grange do not produce veterinary diets).
A note about chicken oil

The chicken oil used in the Arden Grange dry recipes (including the Sensitive) is not usually problematic for dogs with chicken allergies, since a food allergy is an adverse immune response to a dietary protein rather than a fat. Our oil is a pure source which has been filtered to remove any large, antigenic protein molecules, and its high digestibility and low inclusion level mean it is rarely something dogs are intolerant to. Arden Grange Partners is chicken-free if you need or wish to completely avoid this ingredient.

As a precaution, if your dog is known to be very sensitive to chicken and you do decide to trial a Sensitive dry product, double the introductory period from 7-14 days. This way, if there is an adverse reaction, you should be able to stop feeding the diet before a minor issue becomes a more serious one. 

Nutritional supplements

The Arden Grange products all contain functional ingredients (EPA and DHA from krill, dietary antioxidants, nucleotides and prebiotics FOS & MOS), but there may be occasions when the digestion and immune system will benefit from extra support. Useful supplements may include:

  • Probiotics – Diarrhoea (and antibiotics) can disturb the friendly bowel flora and helping restore the balance by feeding probiotics may help [Honneffer et al, 2014]. Live yogurt is popular, but this is designed for the human gut, and with many dogs being lactose intolerant, and casein (milk protein) being quite a common allergen, it is better to use a commercial supplement formulated for canines such as Lintbell's yuDIGEST. Probiotics may be contraindicated in cases of pancreatitis.

  • Fibre – Fibre supplements should be used with caution because the appropriate amount and type (soluble, insoluble or a combination) depends on the cause of diarrhoea. Some conditions such as IBD may respond better to a lower intake of insoluble fibre.      

  • Multi-functional Digestive Support – Protexin Pro-Kolin Enterogenic is a dietary supplement containing alpha-glucan butyrogenic (a resistant starch), MPS Protect (a mucopolysaccharide to help protect the intestinal wall), pre and probiotics and beta-glucans (a type of soluble fibre).   

  • Natural remedies – Only use natural remedies from reputable sources (e.g. Dorwest Herbs’ Digestive Tablets or Tree Barks Powder which help to protect the gut lining). Check with your vet that these are safe to give in conjunction with conventional medication, if applicable. 
Important notice

As a responsible and ethical company, Arden Grange fully appreciate that caution must be taken when discussing the potential benefits of our diets. Whilst our recipes may be beneficial to some dogs, we must highlight that they are not a substitute for veterinary intervention in the case of a sick animal.

Shop the products mentioned in this fact sheet

Case, L., Hayek, G., Daristotle, L., Raasch, M. (2011). Canine and feline nutrition. Maryland Heights, Mo.: Mosby. P455. Honneffer, J., Minamoto, Y. and Suchodolski, J. (2014). Microbiota alterations in acute and chronic gastrointestinal inflammation of cats and dogs. World Journal of Gastroenterolgy, 20(44).