How long does it take a dog to digest food?

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Written by Dr Andrew Miller MRCVSDr Andrew Miller MRCVS is an expert veterinary working in the field for over 10 years after graduating from Bristol University. Andy fact checks and writes for Pure Pet Food while also working as a full time veterinarian. - Our editorial process

A dog’s diet and their digestive system play a huge role in their health. We all know that what our pets eat, and the nutrients they receive, are key to keeping them well. However, just like human food, not every dog’s dinner is equal in its nutritional value.

Not to mention, the majority of your dog’s immune system is linked to what happens in their gut. This means that feeding them the right diet to maintain their digestive health is really important in helping to maintain their overall health.

Knowing how a dog digests their food is as important as knowing what they should eat when it comes to understanding the wellbeing of your pup. If their digestive system isn’t working as it should be, your dog won’t be getting the nutrients they need from their food. Plus, it could be a symptom of illness, making it important to understand how your dog’s digestive system works so that you can notice any irregularities sooner.

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But how does a dog digest their food? How long does it take a dog to digest food? How can you tell their gut is working normally?

We’ll answer these frequently asked questions and more as we walk you through the basics of understanding how your dog’s digestive system works, the main factors involved in the process of digestion, and how food itself impacts your dog’s digestion.

Understanding your dog's digestive system

How does a dog's digestive system work?

The dog digestive system includes all the organs involved in eating and processing food. It begins the moment when food enters the mouth, moving through the body and all usable nutrients are absorbed into the body, and any waste is excreted from the body as faeces.

At its simplest, a dog’s digestive system is a long tunnel that runs from their mouth to the anus. Food goes in at the mouth and travels through this tube and at various stages is broken down and either absorbed into the body or excreted as waste at the anus.

To put it in a little more detail, here are the main stages of the canine digestive system.

The mouth

The first stage of digestion begins in the mouth. The dog’s teeth tear their food into smaller pieces, and enzymes found in their saliva break down the food on a chemical level.

The stomach

The food is then swallowed and travels down the oesophagus to reach the dog's stomach. Once there, stomach acid breaks the food down further.

The small and large intestines

The food then moves from the stomach and into the intestines. The small intestine is responsible for absorbing most of the nutrition from the food.

Here, bile from the gallbladder is added to the food to bind it and neutralise any remaining stomach acid. Enzymes from the pancreas are added to help further break down their food and help to speed up the chemical reactions that digest and absorb it.

Then the food’s nutrients are absorbed through the intestine walls into the blood to be carried throughout the body to be used. The liver is crucial in this process, as this is where the nutrients from the food are metabolised.

This means that by the time your pooch’s food reaches the large intestine, most of the useful compounds have already been absorbed into their body. Anything without nutritional value, or that cannot be broken down and digested, is pushed through the large intestines where any remaining water in the food is absorbed into the body. The waste is then formed into a stool.

Rectum and beyond

This waste is stored in the rectum until there is enough there to trigger a reaction that urges the dog to defecate. Then once nature calls, the waste is removed from the body when the dog goes to the toilet.

How long does it take a dog to digest food?

As a rule of thumb, it will take somewhere between 6 and 8 hours for food to pass through a dog. However, there are several factors that can influence your dog’s “normal” digestion time. How long it takes a dog to digest food will depend on their age, size, dog breed, and health conditions.

However, the greatest influence on how long it takes a dog to digest food is the food itself.

Firstly, wet food will digest faster than dry food. After that, the biggest factor is the quality and digestibility of the food and its ingredients.

Significant factors that influence how long it will take a dog to digest food are:

  • Breed

  • Size

  • Age

  • Hydration

  • Existing health conditions

  • Illness

  • Type of food (Wet vs Dry)

  • Digestibility of their food

What is digestibility?

Digestibility is a way of measuring how many nutrients a dog can absorb from the food they are eating. It is a key measure of food quality.

A highly digestible food is one which your dog can more nutrients from the measured volume of food. Food with lower digestibility is where the acid is not absorbed into the body and instead is excreted again in their faeces.

In other words, more digestible food offers greater nutritional value for the volume of food. A more digestible food allows more nutrients to go into your dog’s body. Whereas a dog eating less digestible diet will need to eat a greater quantity of food in order to absorb the same amount of nutrients.

For example, say your dog eats 100g of food and later produces 18g of stool.

18g is 18% of their food intake. This means 18% of their food was waste, so they only absorbed 82% of their food into their body.

If one food offers 82.0 digestibility, and another only 74, then it is clear that the second food is not as digestible. This is because far less is being absorbed and it is not offering as much nutritional value. It also means the dog will be producing more faeces than if they ate a more digestible dinner.

As a rule of thumb, dog food digestibility can be ranked in this way:

  • < 75% = Low quality food

  • 75% to 82% = Moderate quality food

  • < 82% = High quality food

The benefits of highly digestible food

Digestibility is important for the short and long-term wellbeing of your dog. In the short term, it affects the quality and volume of stool the dog produces and their flatulence levels. A dog eating highly digestible food will be producing less waste, and their faeces will be firmer. (Making it easier to pick up.)

In the long term, a highly digestible diet will lead to benefits such as a healthier digestive system, as their gut is not having to overwork to process their food. This will help prevent conditions such as colitis. Additionally, your dog will develop healthier skin and fur, as they will be ingesting all the nutrients required to support a healthy body. It's also theorised that a highly digestible, nutrient-dense diet can help your dog's behaviour, encouraging stable moods and a happy dog. Check out our blog, where we have a full post all about how nutrition and your dog's behaviour link together.

What increases food digestibility?

Two of the biggest factors in digestibility are the proteins used in the dog’s food and the processing methods in making the food.

Which protein sources are best for a dog's digestive system

The protein source used to make the dog’s food will impact on the overall digestibility of their food. Different forms of meat have different digestibility values, and the higher the value, the more nutrients your dog will absorb from the food.

There are two main reasons why there are differences between protein sources. The first is because different meats have different levels of digestibility, for example, fish vs lamb.

Experimentation between three of the main proteins used in dry dog food; fish meal, poultry meal, and lamb meal, compared their relative digestibility.

When ranking digestibility in this way, poultry meal and fish meal offered the most complete nutrition. Fish meal digestibility was 87.0, whereas poultry meal was 80.2.

This means not only are chicken and fish higher quality sources of protein and easier for dogs to digest, but they provide more of the essential nutrients required for a healthy dog.

This contrasts to lamb meal, another popular protein used in dry dog food. It was found that lamb meal only had a digestibility value of 71.5, making it significantly lower quality protein than chicken or fish, and had a much lower nutritional value.

These meat meals are an example of the proteins, when looking on the back of your dog food for what protein is in the food make sure you don't choose a meal. Look for the protein (chicken, beef, fish etc.) on its own, meal is a much lower quality protein source as it can contain slaughterhouse by-products, hooves and feathers to name a few. At Pure we only use the very best human-grade muscle meat and never use meal.

How does processing food affect its nutritional value?

The second difference is determined by the source of the protein and how it is processed in food production. This typically comes down to meal vs raw meat. For example, raw chicken has a value of 88.2 whereas rendered poultry meal (which is the basis of most dry dog food) is only 80.2.

This means that the source of the protein and how it is rendered has a significant impact on the digestibility of the dog food. However, it is the processing of the food rather than the base ingredient that appears to have the most significant impact on the digestibility and nutritional value of the food. In other words, the more processed the food, the lower the digestibility value.

This was explored in a study which found even when using raw chicken as an ingredient in dry dog food (brown biscuits), it did little to improve the overall nutritional value of the resulting food.

When a significant quantity of the poultry meal used in food production was replaced with raw chicken, the end product saw little change in the overall digestibility value of the food. Despite replacing a quarter of the poultry meal in the food production with raw chicken, the digestibility of the food only increased by 1%.

In short, this means that the process of creating the food was the main factor which decreased the digestibility of the food. Therefore, regardless of the protein source and it’s own individual digestibility value, the act of extruding it to create dry dog food (brown biscuits) was the primary factor in decreasing the food’s nutritional value.

How can you know the value of your dog's food?

Luckily, there is now a push for pet food manufacturers to be more open about the ingredients of their food, how it's made, and the digestibility value of their food.

There are also welcome alternatives to dry kibble (brown biscuits) and it’s lower digestibility. They are also safer than an alternative raw food diet, which carries the risk of harmful bacteria such as E. Coli and Salmonella being ingested by your dog and making them ill.

Pure Pet Food is a highly-digestible alternative, made from high-quality whole ingredients in our human-grade kitchen. The food is then gently air dried to preserve it, extending its shelf life without damaging the nutritional value of the food. It also removes the risk of harmful pathogens, unlike a raw diet.

What happens to food that can't be digested?

A dog’s stool is made up of water, undigested food, some bacteria, and inorganic matter that cannot be digested.

The undigested food is often made up of nutrients that can’t be absorbed into the body due to low digestibility, or simply cannot be broken down, like fibre.

For example, you might find fragments of vegetables in your dog’s stool. This doesn’t necessarily mean your dog hasn’t been able to digest it properly. They will still be able to remove the nutrients, it is just that vegetables are a source of fibre. Fibre is a non-digestible carbohydrate, but is still very important for digestive health, just like in humans.

Your dog’s stool is a good indicator of their gut health, which in turn, can say a lot about their overall health. This is why if your dog exhibits behaviour out of the norm, such as constipation, diarrhoea, or straining while toileting, it is important to monitor your dog and discuss with a vet.

Problems with your dog’s stools, and issues with digestion, are often a symptom of a more significant problem. For example, if your dog develops diarrhoea it may be a symptom of stress, poor diet, parasites, or digestive and gastrointestinal issues, such as colitis or malabsorption.

This is why having an understanding of your dog’s digestive system and their normal habits is an important part of ownership. By knowing what is normal for your pup, you and other dog owners will notice irregularities sooner and can seek veterinary advice. It also gives you a greater understanding of what is best to be feeding your dog to keep them at their healthiest and happiest.