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Why do dogs have diarrhoea?

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Dogs with diarrhoea

By Dr. Stephanie Holmes BVetMed BSAVA PGCertSAECC MRCVS Veterinarian

Updated on the

Diarrhoea is very common in dogs and most cases are not serious. But if you think it might be something worse, a trip to the vets could be necessary. 

Diarrhoea is the increased frequency or quantity of poop (faeces) production. Diarrhoea has an increased water content that is caused by increased secretion of fluid into the intestine, reduced absorption of fluid in the large intestine or rapid transit of stool through the intestines. It can also contain mucus or blood.  

It is very common in dogs and is one of the main reasons a dog might visit the veterinary surgeon. Most cases of diarrhoea are not serious and will self resolve or be easily treated. Occasionally diarrhoea can be a symptom or something more serious.

Bloody diarrhoea in dogs

Bloody diarrhoea is not uncommon and not always a cause for concern. However we would always recommend a check up at the vets if any blood is seen in the faeces. It could occur with irritation of the gut lining, infections, problems with the blood clotting or some tumours. Fresh blood in the faeces is seen if there is a problem with the large intestine (the latter part of the gut), but if there is blood coming from the small intestine, stomach or potentially swallowed this will look black or tar-like.

Diarrhoea in dogs

Diarrhoea is common in dogs, especially due to their scavenging nature. It is often linked with or follows vomiting. There are many reasons that a dog will develop diarrhoea. Commonly, diarrhoea occurs when a dog eats something it shouldn’t or a sudden change in diet. Sometimes dogs may eat foreign (non-food) objects that could cause diarrhoea or an inability to go to the toilet. Infections e.g. bacterial/viral/parasites, including worms, can also be common causal agents of diarrhoea. Less commonly food allergies, diseases of the liver or pancreas and some cancers may cause diarrhoea as a symptom. Stress and heatstroke can also cause diarrhoea. Some dogs also can produce more sloppy poop if they are very active on long walks.

Most of the time diarrhoea will not trouble your dog and will clear up within two to three days. If the diarrhoea is bothering the dog, if he is unwell – not eating or lethargic, in pain, or if the diarrhoea isn’t clearing up within a couple of days – it’s strongly recommended you take your dog to the vet for a check up.

Puppy diarrhoea

Diarrhoea in puppies is also fairly common. Veterinary intervention and treatment may be required earlier in the illness as puppies are at a higher risk of having diarrhoea due to an infection, whether it be bacterial, viral or parasitic. These are contagious to other dogs and may also be contagious to people (which is known as being zoonotic). Puppies also dehydrate from loss of fluid due to diarrhoea more quickly than healthy, adult dogs, so they may need to be hospitalised for a drip.

Puppy diarrhoea may also occur when you first bring the puppy home due to the change in water, diet and also the stress of leaving their mother. It is recommended to keep the puppy on the same complete puppy food that the breeder was feeding them and change slowly over at least a week, if you do want to change the food.

My dog has diarrhoea

If your dog has diarrhoea and you are worried, then a trip to the vet is recommended. Along with taking a history of diet, any recent diet changes, scavenging, access to poisons, vaccine status and worming history, a vet will do a full physical examination of your pet. Treatment may then be prescribed or further tests be recommended. These might include faecal samples, blood tests and, later on, imaging tests (x-rays or ultrasound) for the intestines.

Sickness and diarrhoea in dogs

Sickness and diarrhoea in dogs are often linked together as they are symptoms of disease processes within the gastrointestinal tract (the stomach and intestines). Vomiting often occurs as a protective mechanism to rid the stomach of something that could be toxic, harmful or irritant. Diarrhoea occurs if the intestines are affected to expel noxious waste products. Disease conditions that affect the working of the digestive tract will often have vomiting and diarrhoea as symptoms. In cases of gastrointestinal infections or eating something harmful, the stomach will be affected before the intestines and so vomiting usually occurs first, followed by diarrhoea 12-24 hours later.

When should I be concerned about my dog's diarrhoea?

You should be concerned about the diarrhoea if it is uncontrolled, the dog is not well, lethargic, in pain and not eating or drinking as he usually would. If there is any blood or black colour to the diarrhoea you should also seek prompt veterinary attention.

How long does dog diarrhoea last?

Diarrhoea can last anywhere from one day to many months. Simple cases of diarrhoea will clear up within two to three days. Some ongoing conditions such as food allergies and intolerances, problems digesting or absorbing food and irritable bowel will often be lifelong. These should, once diagnosed, be well controlled with the correct treatment, but your dog may be prone to flare ups and bouts of diarrhoea.

What stops diarrhoea fast?

Treating the underlying cause is generally the best way to clear diarrhoea up. Occasionally a vet will prescribe drugs to help if your dog is unwell or the diarrhoea isn’t clearing within a couple of days.

Easily digestible food, such as chicken, rice, pasta, boiled potato, egg, given little and often, will help. It is no longer recommended to starve your dog if he has diarrhoea, as the lining of the gut needs the nutrients directly from the diet in order to heal.

Can I give my dog Imodium for diarrhoea?

Imodium (a human medication used to decrease the frequency of diarrhoea) can be given in some cases of diarrhoea. As it is a human drug, before it can be safely administered, it must be prescribed by a veterinary surgeon. Imodium usually works very quickly to stop diarrhoea. Some dogs do not tolerate Imodium or it can interfere with other drugs your pet may already be taking. Always seek veterinary advice before giving any drugs to your pet.

How can I stop my dog's diarrhoea fast?

Diarrhoea is a protective mechanism to rid the body of harmful waste products, or as a symptom of disease processes. There are some products that include natural clay and probiotics that may help to bind the diarrhoea and form the faeces. Treatment of the underlying disease process will also stop the diarrhoea.

Should you let diarrhoea run its course?

Generally speaking, yes, diarrhoea is best left to run its course. There are some instances where it may be preferable to give treatment to help bind the diarrhoea or for underlying diseases. Especially if diarrhoea is lasting more than a few days, or if the dog is losing a lot of fluid and unwell.

How long is too long for diarrhoea?

Given most simple cases of diarrhoea usually clear up in two to three days, it is recommended that if the diarrhoea is continuing after this point then treatment from a vet may be needed. In some cases diarrhoea may last for weeks or months – for example if a dog had an underlying allergy or intolerance, or other long-term medical conditions.

What can help a dog with diarrhoea?

Making sure a dog is getting enough calories in easily digestible form e.g a bland diet of chicken and rice. Also ensure they have enough fluid to drink for their normal requirements plus covering the loss of fluid in the diarrhoea (you might notice your dog is more thirsty when he has diarrhoea). Probiotics might help to rebalance the guts' “good bacteria” (known as microbiome), although research is currently underway in this area.

Allow your dog free access to the outside if possible and keep him warm and comfortable. He might want to rest and it is advisable to avoid walking him where other dogs poop walk – if it's possible the diarrhoea is due to an infection, to minimise the spread of the disease. If your dog is unwell at all or diarrhoea lasts more than two to three days, please seek veterinary advice.

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