The Dog Digestive System: A Beginners Guide to Your Dog’s Anatomy

Your dog’s digestive system is a hub of activity and a major
junction in their bodies. It’s a long journey through the entire
gastrointestinal tract, and each stop plays a critical role in your
dog’s health. 

Caring for your dog’s digestive system may seem complicated,
but this blog will break down the digestion process and give you a
better understanding of how to care for your dog’s digestive

A Quick Tour of Your Dog’s Digestive Tract

Let’s take a look at the full digestion process from start to
finish. Knowing where each critical point of digestion is and how
it works may help you understand how to improve your dog’s
gastrointestinal health.

Mouth and Teeth

Your dog’s mouth is the first stop of the digestive train.
Chewing and saliva help to break down food into a smaller, more
easily digestible format. Their sharp molars cut food vertically,
like scissors, instead of the flat molars that we use to grind our

Dogs are anatomically designed to tear flesh and swallow large
pieces of meat at a time. This is evident by their wide-set jaws
and large esophagus.

Feeding raw dog food caters to their ancestral dietary needs,
but the most popular food formats for domesticated dogs are kibbles
and other cooked foods. Dogs are capable of digesting these food
formats, but they often take longer to break down and require
proper chewing to ensure digestibility. 

Did You Know?

Caring for your dog’s teeth is an important part of caring for
their digestion. Poor dental health can encourage bad eating
habits. Their mouth can be a breeding ground for bacteria to
flourish if you are not properly caring for their teeth. 

Make sure that you have a solid pet dental
routine in place to prevent issues down the road.

Esophagus and Stomach

Once your dog has chewed and swallowed his food, it travels down
the esophagus to their stomach. The muscle around the esophagus
contracts and releases to push food down the esophageal

Your dog’s stomach is a very acidic environment that is
necessary for breaking the food down to a substance called

Chyme is a gooey mixture of food, water, and stomach acids. This
form allows the food to travel to the next stage of digestion where
nutrients can be separated and absorbed. 

Did You Know?

The extremely acidic environment of their stomach eliminates
much more bacteria than our stomachs do. This allows them to safely
consume raw meat and bones. 

In healthy dogs, nominal amounts of bacteria that are typically
found in raw meat are
unlikely to cause any adverse effects
. The risk is higher in
dogs with compromised immune systems or if there is a large number
of bacteria present in the food. 

The Intestinal Tract

Now that the food has been turned to chyme, it will pass through
the powerhouse of digestion, the intestines. Each stage of the
intestinal tract works to breakdown food into its smallest forms,
prevent bacterial colonization, and deliver energy and nutrients to
the rest of the body. 

Did you Know?

70% of your dog’s immune system is located in their digestive
tract, more specifically their intestines. This is why some
digestive issues can present as a skin reaction similar to what you
might see in food allergies or intolerance. 

In reality, these reactions are more likely a result of poor

When their immune system doesn’t recognize a nutrient, it is
treated as a foreign body. Defenses go up, and the body tries to
eliminate any threat, releasing inflammation to nearby cells. 

Small Intestine

The small intestine is made up of three sections: the duodenum,
jejunum, and ileum. In total, the small intestine is roughly 25% of
the entire intestinal tract and it plays a pivotal role in nutrient
absorption and immunity.  

The duodenum, the first section of the small intestine, has two
distinct functions. It has glands that secrete mucus which
neutralize the intense stomach acids in the chyme. 

It is also connected to the pancreas, liver, and gallbladder
which secrete enzymes and bile that further breakdown food into
smaller components. The bile duct passes bile from the liver to the
gallbladder and intestines which aid in fat digestion into its
fatty acid components. 

The pancreas is responsible for secreting digestive enzymes like
Amylase, Protease, and Lipase. These enzymes are designed to break
down carbohydrates, proteins, and fats respectively. 

Next, the food passes through the jejunum and ileum, which are
responsible for absorption and immunity. The intestines are lined
with small, finger-like protrusions called villi, which are covered
in even smaller “fingers,” called microvilli. 

The microvilli are fine hair-like projections that absorb
nutrients through the intestinal lining into the bloodstream,
organs, and lymphatic system. 

At this stage, nutrients are filtered to their appropriate
destinations and checked by the immune system via the lymph nodes
to prevent bacteria, pathogens, and poorly digested nutrients from
harming your dog. 

Did You Know?

Inflammation in the bile duct can severely compromise digestion
and liver function and other organs, as well as result in a
decrease in blood flow in those areas. Bile duct obstructions are
rare, but chances are increases by other digestive system

Common illnesses that can cause or exacerbate a bile duct
obstruction include pancreatitis, gastroenteritis, and
liver disease

Symptoms of these diseases can include loss of appetite,
vomiting,  and diarrhea. If you see any of these symptoms in your
pet, contact your veterinarian immediately. They can diagnose your
pet and prescribe antibiotics to prevent infection during the
healing process.

Large Intestine


Also made up of 3 sections: the cecum, colon, and rectum. The
large intestine deals with the digestion of dietary fibres and
absorption of water from what will be the final waste product.

Once it reaches the large intestine, dietary fiber acts as a
bulking agent to bind and drag out toxins and bacteria, as well as
to apply pressure to the anal sacs, releasing even more bacteria as
the waste is excreted. 

Your dog’s stool is made up of indigestible fibers, water, and
the by-product of digested foods. This waste cycle can also
eliminate nitrogen that is produced during protein digestion and
bacteria in the food that wasn’t eliminated during

During digestion, the acids and enzymes can’t kill all
bacteria, but bile and digestive juices can prevent it from
colonizing in their digestive system. Many pathogens, like
salmonella and e. Coli are naturally excreted with the stool. 

Caring for Your Dog’s Digestive Health

While your dog’s digestive system is designed to handle
a lot, it does require some intervention on your part. What you put
in makes a huge difference in how effective this system runs.

Dogs are designed to eat fresh, minimally processed foods, so
feeding an unnatural diet can limit the efficiency of the whole
system and have lasting effects on the rest of the body. 

Kibble, being the most convenient, cost-effective, and
widely-available food format for dogs, is very popular, but not
every kibble diet is suited to how their bodies process food. Carb
heavy, artificial foods that use high-temperature cooking processes
can leave nutrients from food altered and difficult to digest,
leading to poor nutrient absorption and digestive issues. 

In addition, dry food can lead to dehydration. Whether you are
feeding a dog or cat, or a human for that matter, moisture plays a
large part in the digestive process. Feeding wet food can
drastically improve digestion. 

Choose the Right Ingredients

When choosing a food for your dog, look for natural, real food
ingredients over synthetic additives. When possible, feed as many
fresh ingredients as you can. Fresh vegetables and fruits contain
essential vitamins and minerals that are easy to digest and

minimally processed foods
provide complete and natural
nutrition, as well as a variety of health benefits. Even if you
aren’t feeding a raw diet, incorporating fresh food will improve
digestion and contribute to overall health. 

Did You Know?

Fruits and vegetables have an outer layer called cellulose. This
layer is indigestible to dogs, so removing the cellulose by
grinding or mashing the produce will make it easier for your dog to

Beware of Kibble

Dogs have adapted to digesting extruded kibbles and cooked
diets, but they simply don’t hold a candle to a fresh minimally
processed diet. Many processed foods are subjected to high heat,

killing many of the much-needed enzymes, bacteria, and
that your pet needs. 

Foods that rely too heavily on carbohydrate sources for proteins
and minerals may not be providing your dog with everything that
they need to thrive. In fact, they may be providing too much of
some less desirable nutrients, like sugars. 

Simple carbohydrates like corn, wheat, and even potatoes can
affect blood sugar and feed bacteria that contribute to digestive
issues in dogs. A little bit is fine, but some commercially
produced dog foods overuse these ingredients.

Instead, look for complex carbohydrates that provide vitamins,
minerals and dietary fiber in place of those that only provide
cheap energy sources. Feeding your dog carbs is perfectly healthy
as long they are whole, healthy, and in appropriate

Canine diets should also be rich in protein and fat to get
optimal sources of essential fatty acids, amino acids, and energy.
This will support all the systems of the body, help to build and
maintain muscle mass, and improve the efficiency of their digestive

Of course fresh is still best, but if you are feeding a cooked
diet, make sure that the animal products come from a named meat or
meat meal. Avoid by-products, with the exception of organ meat, and
“mystery” meats and vague wording, like “meat meal.”

Gut Flora

Your dog’s gastrointestinal tract is full of bacteria, but
don’t worry, there is such thing as good bacteria. This type of
bacteria aids in digestion and is always present. 

Dog’s with poor digestion are typically lacking either the
number of bacteria needed to support the system or their diet is
not providing food for the bacteria to continue to populate. 

The healthy bacteria that we are talking about are called
probiotics. They work in conjunction with the digestive enzymes
provided by the pancreas to break down food. 

Depending on digestive health and diet, it can be beneficial to
add a probiotic supplement to your dog’s diet. This will increase
the population of good bacteria and support digestion. 

Check out
5 Key Benefits of Probiotics for Dogs
, to learn more about how
adding probiotics can help your pet. 

Fermentable fibers in their diet will, you guessed it, ferment
during digestion, creating a sugary food source for their natural
bacteria. These are called prebiotics. 

You will often see prebiotics added to commercial pet foods to
ensure that their bodies can maintain appropriate probiotic levels
and to improve the digestive function. 

Look for fructooligosaccharides (FOS) or Inulin in the
ingredient list to find out if your dog’s food has this valuable
fibre source. Foods like barley, oats, and beet pulp all contain
prebiotics to aid digestion. 

Both pre- and probiotics can be added to any diet to further
increase digestion. Powdered digestive aids can be added to your
pet’s diet to improve digestion and reduce common tummy upsets.
It can also help to reduce flatulence and tummy gurgling. 

Digestive enzymes produced by the pancreas also need to be
supported in cases of sensitive digestion. Supplements that contain
digestive enzymes, like Naturvet’s Digestive Enzyme Chews,
can be fed to boost naturally occurring levels and take some of the
strain off of the pancreas. 

Did You Know?

Dogs with Diabetes Mellitus are typically afflicted with other
diseases that can affect the pancreas. Diabetes can contribute to
poor digestion, unbalanced gut flora, chronic pancreatitis, and can
even affect kidney
and liver function
. Dogs suffering from diabetes will greatly
benefit from the inclusion of digestive aids. 

Food Fuels Life

Whether your dog is suffering from digestive issues, or you are
just acting preventatively, digestion is the center of whole-body
health. The right diet can maintain healthy digestion, and help to
relieve symptoms of poor digestion. 

Now that you understand how your dog breaks down food, it’s
time to take a good look at what you are feeding them. Can some
digestive issues be attributed to diet? Are you giving your dog
everything they need to thrive? 

Many aspects of their health are connected to how they digest
their food. It’s never too late to try new things. Start by
adding some fresh ingredients, switching to a higher-quality diet,
or adding digestive aids to your pups food. You’ll be pleasantly
surprised by the results.

Author Bio: Krystn Janisse is the content
writer for and a pet
nutrition enthusiast. She has worked in many facets of the pet
industry for over a decade and loves to share her passion for
animal welfare with others.

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The Dog Digestive System: A Beginners Guide to Your Dog’s
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Source: FS – TheDogTrainingSecret
The Dog Digestive System: A Beginners Guide to Your Dog’s Anatomy