Why do dogs develop digestive problems?

Digestive problems are one of the most common health concerns in dogs. Signs such as diarrhoea, vomiting, gas, poor appetite, or what owners often describe as a “sensitive stomach” can all indicate that something isn’t working properly in the digestive system.

To understand why these problems occur, it helps to first understand how digestion normally works in dogs.

How your dog’s digestive system works

Your dog’s digestive system is made up of several organs working together, including the mouth, teeth, salivary glands, oesophagus, stomach, intestines, pancreas, liver and gall bladder.

While digestion technically starts in the mouth, in practice much of the work begins in the stomach. Here, food is mixed with stomach acid and digestive enzymes, and broken down into a semi-liquid mixture called chyme.

From the stomach, chyme moves into the small intestine. This is where the majority of digestion and nutrient absorption take place. The pancreas releases enzymes that help break down protein, fat and carbohydrates, while the liver produces bile that helps digest fats. Nutrients are then absorbed through the intestinal wall into the bloodstream so they can be used by the body.

After this stage, the remaining material moves into the large intestine (colon), where water and electrolytes are absorbed and gut bacteria ferment some undigested material. The final waste is then formed and passed as stool

Why is digestive health so important?

A healthy digestive system is essential for overall health. Even the highest-quality food cannot support your dog properly if nutrients are not digested and absorbed efficiently.

Digestive problems can develop for many different reasons. Infections, inflammation, food sensitivities, pancreatic disorders and other medical conditions can all interfere with normal digestion. Identifying the exact cause can sometimes be challenging, which is why careful work-up by a veterinarian is important.

The encouraging news is that nutritional management often plays a major role in improving digestive health, regardless of the underlying cause

How diet can influence digestive health

The most appropriate diet will depend on where the problem originates in the digestive system and your dog’s dietary history.

The small intestine

Problems affecting the small intestine often interfere with digestion and nutrient absorption. These dogs may struggle more with nutrients that are harder to digest, particularly fat, and may need a diet that is highly digestible and carefully controlled.

The large intestine

Problems affecting the large intestine often affect stool consistency, urgency, mucus, and gut bacteria. In these cases, fibre can be especially important, as it helps regulate stool quality and supports the bacteria living in the colon.

Protein

Protein can be a problem when the immune system reacts to certain dietary proteins. This may happen in dogs with food-responsive enteropathy or suspected food sensitivity.

In these cases, an elimination diet may be recommended. This usually involves feeding either a novel protein that the dog has not eaten before, or a hydrolysed protein – where the protein has been broken down into smaller pieces that are less likely to be recognised by the immune system – although they do not work in every dog.

Fat

Fat is more complex to digest than protein or carbohydrate. It requires bile from the liver and gallbladder, as well as pancreatic enzymes, before it can be properly broken down and absorbed.

Because of this, some dogs with digestive disease, especially small intestinal disease, pancreatitis, or fat malabsorption, may benefit from a lower-fat diet.

The type of fat may also matter. Adjusting the balance of omega-6 and omega-3 fatty acids may help support a healthier inflammatory response. In some situations, medium-chain triglycerides, or MCTs, may be useful because they are absorbed differently from long-chain fats and are generally easier to digest.

Carbohydrates

Carbohydrates in the diet include both digestible starch and non-digestible fibre. While they are often grouped together, they can have very different effects on a dog’s digestive health.

Starch

Starch tolerance varies between dogs. In small intestinal disease, highly digestible starch sources such as well-cooked white rice or peeled potato are often better tolerated, as they are absorbed earlier in the digestive tract.

In some dogs, poorly digested starch may reach the large intestine, where it can be fermented by bacteria and contribute to gas, loose stools, or discomfort. In these cases, adjusting the type or amount of starch may help.

Fibre

Fibre can play an important role in digestive health, but its effect is very much an individual response.

In large intestinal problems, a mixture of soluble and insoluble fibre may help regulate stool consistency, reduce urgency, and support beneficial gut bacteria.

However, in some small intestinal conditions, too much fibre can make symptoms worse by reducing digestibility, increasing stool volume, or contributing to gas and discomfort. This is why fibre needs to be adjusted carefully rather than simply increased.

Supplements that may support digestive health

Some supplements may help support dogs with digestive disorders.

Fish oil for dogs

Fish oils provide omega-3 fatty acids that may help reduce inflammation.

Probiotics for dogs

Some probiotic products may help in certain digestive conditions, but benefits depend on the product and the individual dog

Digestive enzymes for dogs

Digestive enzyme supplements can help break down and absorb nutrients from their food. However, they are mainly used for dogs with exocrine pancreatic insufficiency rather than as a routine supplement for all digestive problems.

Psyllium husk for dogs

Psyllium husk can be useful in some dogs, particularly those with large intestinal issues. It is a soluble fibre that absorbs water and forms a gel-like substance, which can help regulate stool consistency, supporting both loose stools and mild constipation. It may also support beneficial gut bacteria.

However, psyllium is not suitable for every dog. In some small intestinal conditions, or if used in excessive amounts, it may worsen symptoms such as bloating or discomfort. As with all fibre sources, it should be introduced gradually and adjusted based on the individual dog’s response.

Why does my do have a sensitive stomach?

A “sensitive stomach” in dogs usually reflects how their digestive system reacts to food, diet changes, or underlying health issues.

Occasional digestive upset

Many dogs experience mild digestive upset from time to time. This is often triggered by things like sudden diet changes, rich foods, or ingredients that are harder to digest. These cases are usually short-lived and improve once the diet is stabilised.

Ongoing or more severe issues

In some dogs, a “sensitive stomach” may be linked to a more persistent problem. This can include food intolerances, inflammation in the digestive tract, pancreatitis, or chronic gastrointestinal disease. These cases often require more targeted dietary management and, in some cases, veterinary investigation.

Why does my dog get diarrhoea after eating?

Diarrhoea after eating can happen when food is poorly digested, poorly absorbed, irritates the gut, or moves too quickly through the intestines

This can be triggered by food intolerances, sudden diet changes, infections, or conditions affecting the pancreas or small intestine. In some dogs, poorly digestible ingredients or diets that are too high in fat may overwhelm the digestive system and lead to lose stools shortly after eating.

How long does food stay in a dog’s digestive system?

Food does not pass through every dog at the same speed. Stomach emptying and intestinal transit can vary widely depending on the diet, meal size, the individual dog and whether digestive disease is present.

When digestive problems may indicate a medical condition

Digestive problems may indicate an underlying medical condition when they are persistent, severe, or accompanied by other symptoms such as weight loss, lethargy, or changes in appetite.

While many dogs experience occasional digestive upset, ongoing or recurring symptoms are more likely to be linked to conditions such as pancreatitis, inflammatory bowel disease, food allergies, or certain metabolic diseases.

If your dog has been diagnosed with a specific condition, diet often plays an important role in management. You can read more in these guides:

• Diet for dogs with pancreatitis
• Diet for dogs with inflammatory bowel disease (IBD)
• Diet for dogs with liver disease

What foods are more likely to cause digestive problems in dogs?

Many dogs occasionally experience digestive upset such as diarrhoea, vomiting and gas. When this happens, one of the first questions owners ask is whether something in the dog’s diet might be responsible.

While dogs can tolerate a wide variety of foods, certain ingredients and feeding habits are more likely to upset the digestive system.

Understanding which foods commonly trigger digestive problems can help reduce the risk of stomach upset and support better digestive health.

Very fatty foods

Fat is an important nutrient in a dog’s diet, but it is also the most difficult nutrient to digest.

Foods that are very high in fat can overwhelm the digestive system, particularly if a dog is not used to them. Fatty meats, rich table scraps, and large quantities of treats can all trigger digestive upset.

In some dogs, especially those prone to pancreatitis, high-fat meals can lead to more serious gastrointestinal problems.

Sudden diet changes

One of the most common causes of digestive upset in dogs is switching food too quickly.

The digestive system adapts to a particular diet over time. When a new food is introduced suddenly, the gut and the intestinal bacteria may struggle to adjust.

This is why new diets should always be introduced gradually over several days.

Rich table scraps

When we feed leftovers, it’s often the fatty trimmings, rich sauces, or fried foods that end up in the bowl.
These foods can be difficult for dogs to digest. Even small amounts may trigger diarrhoea or vomiting, particularly in dogs with more sensitive digestive systems.

Large amounts of treats

Treats can quickly disrupt a dog’s normal diet if fed in large amounts.

Too many treats may introduce excessive fat, unfamiliar ingredients, or simply too much food at once, all of which can upset the digestive system.

For dogs with digestive sensitivity, treats are best kept simple and consistent with the main diet.

When digestive problems are not just about food

Although diet can trigger digestive upset, ongoing digestive problems are not always caused by food alone. They often reflect how the digestive system is functioning.

Digestion relies on a coordinated process involving stomach acid, digestive enzymes from the pancreas, bile from the liver, and a balanced gut microbiome. If any part of this process is disrupted, symptoms such as diarrhoea, vomiting, or gas can develop.

For example, some dogs may not produce enough digestive enzymes, making it harder to break down and absorb nutrients. Others may have an imbalance in gut bacteria, inflammation in the intestinal lining, or increased gut sensitivity.

Factors such as stress, infections, parasites, or underlying health conditions can also interfere with normal digestion.

If digestive symptoms occur frequently or do not resolve, veterinary investigation is important to identify the underlying cause.

Key takeaway

Digestive problems in dogs are common and can be influenced by many factors, including diet, gut function, and overall health.
While nutrition often plays a central role in managing digestive issues, there is no one-size-fits-all solution. The most effective approach depends on where the problem originates and how your dog responds to different foods.

If symptoms are ongoing or severe, it’s important to look beyond diet alone and consider veterinary investigation to identify the underlying cause.