Your Dog's Digestive System Explained


This article is written by Pet Circle veterinarian, Teagan Lever BVSc (Hons), in partnership with Hill's Science Diet.

Extracting nutrients from food in order to fuel the many functions of the body is the key purpose of the dog's digestive system. It is a complex process with many components involved from mouth to tail.

In this article we will explore the canine digestive system and ways that you can help maintain your dog's digestive health, starting with answering some of the most frequently asked questions about the dog's digestive system.

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Top Questions about your Dog's Digestive System

Is it better to feed your dog wet food, dry food or both?

The right choice of format for your dog's food depends on their individual needs and can be influenced by a variety of factors including their life stage, breed, taste preferences and health conditions.

For most dogs, it is recommended to feed a combination of both wet and dry food. Feeding a premium dry food, such as Hill's Science Diet is a convenient, and delicious way to ensure your dog is getting the nutrients they need to stay happy and healthy. By combining this with a wet food, you can boost your dog's water intake for better hydration, while also adding some variety to their daily menu. Remember to also always keep fresh water available.

How long does a dog's digestive system take to digest food?

The length of time it takes for food to completely pass through a dog's digestive system is about 6 to 8 hours, although this can vary depending on a number of factors including diet, age and health conditions.

How is a dog's digestive system different from humans?

As both humans and dogs are omnivores, the digestive system of the dog is actually quite similar to that of humans. The length of their intestines are similar, comparative to their size to allow for digestion of both meat and plant material.

A major difference between the digestive system of dogs and humans is that food moves much more rapidly through the digestive system of the dogs. Undigested food is passed as faeces within 6 to 8 hours in dogs compared to 24 to 72 hours for humans.

Can dogs digest grains and carbohydrates?

As omnivores with a longer intestinal tract, dogs are able to digest plant based foods as well as meat. The pancreas of the dog secretes amylase which helps to break down carbohydrates in the diet so that they can be absorbed into the bloodstream and used as energy. In addition, grains can be a useful source of other nutrients including fatty acids, antioxidants, fibre, Vitamin B and Vitamin E.

Your dog's digestive system plays a crucial role in providing their body with the nutrients needed to function properly.

Maintaining Your Dog's Digestive System Health

Problems with the digestive system can cause a variety of symptoms including vomiting, diarrhoea and flatulence. There are a number of things which can cause upsets to your dog's digestive system including:

  • Stress
  • Parasites
  • Dietary indiscretion (eating something they shouldn't)
  • Feeding food or treats that are very high in fat
  • Feeding bones
  • Ingestion of foreign objects (e.g. socks)
  • Food sensitivities
  • Inflammation of the pancreas
  • Bacterial imbalance in the intestines

How to improve your dog's digestive health

Avoid feeding your dog human foods, particularly those that are fatty, look instead for easy to digest treats with a low to moderate fat content.

It is recommended to keep treats to about 10% of your dog's total caloric intake. Bones and foreign objects can cause blockage, injury or inflammation of the digestive system and are best avoided.

One of the best things you can do to support your dog's digestive system health is to feed a high quality, balanced and easy-to-digest food, like Hill's Science Diet. It can also be beneficial to feed a food or designed to support a healthy gut microbiome.

Hill's Science Diet Canine Perfect Digestion contains Hill's exclusive blend of prebiotics, ActiveBiome+, to support each pet's unique microbiome for healthy digestion and overall well-being.

The Hill's Science Diet range has a food to suit every stage of your dog's life.

They have diets for puppies, adults and senior pets with options for small and large breeds.

They also have diets that provide nutrition for a variety of needs, including:

How A Dog Digestive System Works

As omnivores, the digestive system of the dog can digest a wide range of foods, including plant-based foods. Due to the fact that plant matter is more difficult to digest than meat, domestic dogs actually have a longer digestive tract compared with true carnivores such as cats.

The Digestive Process Begins with Smell

The digestion process begins before the dog even begins to eat their food. Anticipation of a meal, or the smell and sight of food stimulates the production of saliva, which aids in digestion and helps with swallowing.

Into The Mouth

The dog then uses their mouth and teeth to pick up food and begin eating. The front teeth (incisors) are suited to picking up individual pieces of food, while the larger teeth at the back are better for grinding and chewing.

The tongue also plays a part in this process, helping to move the food around the mouth and position it for chewing.

Down The Oesophagus

Once the food has been chewed into smaller pieces, the dog swallows and the food travels down the oesophagus to the stomach. It's important for pet parents to be aware that small bones such as chicken necks or wings can easily become lodged in the oesophagus and cause a blockage or injury, so it is best to avoid feeding these.

The Stomach & Intestine Begins Digesting Proteins

Inside the stomach, gastric juice is produced which contains mucus, hydrochloric acid and enzymes to begin digesting proteins.

The walls of the stomach are muscular and contract to physically mix the food as it is broken down.

When the gastric contents are thoroughly mixed they form a thick milky liquid known as chyme. The chyme then passes through the pyloric sphincter of the stomach into the first part of the small intestine, the duodenum.

In the duodenum, more enzymes are secreted from the intestinal wall and the pancreas, including proteases for protein digestion, amylase for carbohydrate digestion and lipase for fat digestion.

Pancreas, Liver & Intestines

The pancreas also secretes sodium bicarbonate, which neutralises the acidic chyme to allow the digestive enzymes to function.

Bile, which is produced in the liver and stored in the gallbladder, is also released into the small intestine to help break down fats into smaller globules ready to be digested by lipase from the pancreas.

Once proteins and carbohydrates have been broken down by the digestive enzymes, their components are able to be absorbed across the wall of the intestine into the bloodstream. Fat is absorbed into the lymphatic system before it eventually ends up in the blood.

Once the food makes it to the large intestine, the bulk of its nutrients have been digested and absorbed. In the large intestine, water is absorbed and there is some fermentation of fibre by bacteria, known as the gut microbiome.

An imbalance of desirable and undesirable bacteria within the gut microbiome can result in excessive fermentation causing symptoms like flatulence or diarrhoea.

Out The Rectum

Once the undigested remnants of the food reach the end of the large intestine, they constitute faeces, which are stored in the rectum and passed through the anal sphincter when your dog takes a toilet break.

There are a variety of factors that can cause upsets to the digestive systems of dogs, including stress, diet and bacterial imbalance in the intestines. By feeding a high quality diet, particularly one designed to support optimal digestion, like Hill's Science Diet, you can help to keep your dog feeling happy and healthy inside and out.

Further Reading

Raw pet food: The benefits and risks

Causes of diarrhoea in dogs

Causes of vomiting in dogs

Premium pet food: Is it worth it?

The scoop on your dog's poop

Flatulence in dogs: How to treat it

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