The eight most common causes of stomach upsets in dogs

The eight most common causes of stomach upsets in dogs

Health & Safety

“I ate a thing and now I’m borked” might be the phrase most commonly used by dogs if dogs could speak; and eating things that they were not offered, that are bad for them, or that in some cases, aren’t even food is a special talent for most dogs.

However, while eating something they should not have eaten may be the most common reason your dog throws up or has an upset stomach, it is not the only potential culprit.

This article will tell you the eight most common causes of stomach upsets in dogs. Read on to learn more.

Dietary indiscretions

A.K.A. “the dog ate something they shouldn’t have had!”

Stomach upsets in dogs caused by what we refer to as dietary indiscretions means everything from eating too much of something that would otherwise be fine, eating something that disagrees with the canine digestive system but that isn’t outright toxic (like dairy products), and eating things that are too rich, or even going off; like if your dog ate roadkill or something decaying that they found in the bin!

Dietary indiscretions in dogs are probably the most common cause of stomach upsets in dogs, which may come on quickly and resolve just as fast.

A sudden change in diet

If you want to change your dog’s food for something else (like another brand or even another format, like from wet to dry, vice versa, or to a veterinary diet or special diet) you should make the change gradually, introducing the new food over the course of a couple of weeks while phasing out the old one.

If you suddenly switch a dog from one food or type of food to another, their bodies can undergo a bit of a digestive shock and they may undergo a short-term stomach upset in the meantime. The one exception to the gradual change rule is if there’s an acute medical need for the switch; such as identifying a food based allergen or the need to feed a diet to support a certain medical condition.

General illness

If your dog is unwell in any way that doesn’t relate to something they ate, this can upset their whole digestive system and other parts of their bodies too. A systemic illness or even an injury can give your dog an upset stomach (if you’ve ever hurt yourself badly this may have made you feel sick in general or suppressed your own appetite too) and so this is something to bear in mind as well.

Poisons and toxins

Ingestion of poisons or exposure to toxins can all cause your dog to develop a stomach upset, and this might be mild and simply allow your dog’s body to expel the source of the problem, or acute enough to be life threatening.

This could be anything ranging from a household chemical to something like chocolate, but something that is outright toxic or poisonous to dogs will almost universally cause a stomach upset if ingested.


Allergies in dogs, particularly food allergies, are apt to cause a number of symptoms and one of these is commonly diarrhoea and general signs of digestive upset. Food allergies in dogs can come in many forms and aren’t always obvious, but even mild allergies to something in your dog’s diet can upset their stomachs.

Foreign object ingestion

If your dog chews up their toys, the chances are they will swallow bits of them even if they don’t mean to; and there are a whole host of weird ways in which dogs can come to ingest things that aren’t food, ranging from small bones in scraps they’ve stolen to whole toys.

If your dog eats something that is not edible, it can cause an internal blockage, irritate the stomach, or cause any one of a number of problems that can cause discomfort and upset your dog’s stomach, and which may be quite dangerous if it is not passed from the body.

Medication side effects

Side effects from medications can upset your dog’s stomach, and more or less any medicine can do this although it is far more common with some canine meds than others.

Medications for chemotherapy commonly make dogs sick, and your vet will warn you in advance if there’s a high likelihood of a medication upsetting your dog’s stomach before you find out the hard way.

Always follow the instructions for giving your dog a medication, as in some cases, things like giving it with (or without) food if directed can help to reduce the chances of stomach upsets occurring. Report any side effects of this type back to your vet too.

Stomach bugs or infections

Finally, infections by all manner of things from bacteria and viruses to fungi and parasites like worms can cause stomach upsets in dogs too, and often these will come on acutely in the case of stomach bugs caused by bacterial or viral infections, make your dog quite sick for a couple of days, and then go as quickly as they came.

It is important to speak to your vet if a stomach upset goes on for more than 24 hours, or sooner if there are other symptoms or your dog cannot keep water down or becomes dehydrated.



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