Dog's Digestive System Breakdown

Food is the fuel that powers your dog’s body, and when welcoming a dog into your home, it’s important that you do your research to determine his specific dietary needs.

While buying the cheapest sack of dry dog food may be tempting, keep in mind that the dog's digestive system is not the same as the digestive tract of humans.

Dog’s Digestive System BreakdownYou need to remember that, unlike our diets, your dog’s diet rarely varies.

For that reason, the food you provide to him needs to meet all of his body's needs.

Whether you feed dry food, canned food, or a homemade diet – it’s important that you understand the canine digestive system so that you can provide your pooch with the nourishment he needs to live a long, healthy, and happy life.

One of the best things about dogs is their variety. You can adopt a big dog or a small dog.

Your dog may be active or lazy. And, even dogs of the same size and breed may be very different on the inside.

Unless you happen to have extensive education in the field of canine nutrition, you shouldn't be making the choice of what to feed your pet on your own.

Seek the advice of your veterinarian or a canine nutritionist to figure out your dog's unique nutritional needs based on his age, weight, breed, body condition, and overall health condition.

RELATED: 9 Tips On How To Feed Dogs with Sensitive Stomachs

Dog Digestive System
and what dogs can and cannot digest

Dog Digestive System

The Route Of Digestion in Dogs

Once your dog ingests any food, either table scraps or dog food, this food then travels through his body, going through a series of processes that are all part of the digestive system.

As the dog has a relatively short digestive process when compared to most other mammals, it can be easy to spot symptoms associated with digestive discomfort.

The dog's digestive system is similar to that of a human, but there are some differences as well. Here are the different parts of the canine digestive tract and the purpose they serve:


The mouth and teeth are the first steps in the dog's digestive system. They are directly correlated, which means proper canine dental care is just as important to ensure the healthy digestive system of your pet dog.

Dog Digestive SystemHave you ever taken a close look at the differences in your dog’s teeth compared to your own? Probably not, but the differences in their teeth make for an entirely different eating process.

I’m sure you will have spotted those big ol’ fangs that your dog has. These are quite aptly called canine teeth.

When we chew food, we use up and down, side-to-side motion. Due to the canine teeth on a dog, they are inhibited from performing any side-to-side movement.

This means that the way that they chew is through up and down motion only. The food then enters the digestive process in a more “whole” form than when humans eat.


If you’ve ever seen a dog wolfing down his food too quickly and then throwing up, don’t worry. This doesn’t mean that he’s unwell.

Instead, it’s the body's way of telling the dog that he hasn’t yet chewed his food well enough to allow it to pass through the esophagus and into the stomach.


Many people assume that the stomach is the most important part of digestion and where the nutrients from the food are divvied out, but in fact, all that the stomach does is break foodstuff down into a liquid.

Once everything is broken down, this enables it to be sorted and processed in the next stages of digestion.

The Digestive System of a DogSmall Intestine

Now that the food has reached the small intestine in liquid form, the walls of the small intestine itself draw out the nutrients from the food and send them into the bloodstream where they will mosey on over to the appropriate cells.

If your dog is on medication, this is also the stage that drugs will be absorbed into the bloodstream, ready to be utilized by the body.


The pancreas is not only part of the digestive system but also a vital part of the endocrine system.

The endocrine system produces and manages hormones and plays a key role in the body's metabolic balance.

The Pancreas secretes digestive enzymes, which are sent into the small intestine to help break down the macronutrients ready for entry into the bloodstream. These enzymes include:

  • Amylase – to aid in the digestion of proteins
  • Lipase – to aid in the digestion of fats
  • Proteases – to aid in the digestion of carbs, including sugars

As well as producing these digestive enzymes, the pancreas has the important role of producing insulin and secreting the correct amount into the bloodstream – depending on the blood sugar level.

Without proper levels of insulin your dog can become diabetic or prediabetic, therefore it’s important to maintain pancreatic health. We’ll go into that in more detail a little later.


I’m not sure whether people forget about the gallbladder, or it’s just not mentioned much because its job sounds gross.

The gallbladder’s job is to store bile that is made by the liver. Charming, isn’t it? Well, yes, actually it is. Bile is necessary to allow the body to break down fats into manageable droplets that are easier for the body to digest.

Large Intestine

The final step in the dog's digestive system is that the large intestine dissolves the harder-to-digest matter with the help of gut bacteria.

It also retrieves any water and minerals that have made their way through the digestive process thus far. Feces are then formed and stored within this organ, awaiting exit via the rectum.

RECOMMENDED: Top 5 Best Digestive Enzymes for Dogs

Dog Digestive System

Evolution of Dog's Diet

The ideal canine diet has evolved over the years, starting way back when the domestic dog was the wild wolf. His diet was made up almost entirely of meat.

Over the years, like the domesticated dog we see today evolved, his relationship with man has played a key role in his diet. His body adapted to the food sources available, and often, that was the scraps of his human companions.

For that reason, today’s dog is far more adept at digesting starches, fats, carbohydrates, and proteins. It is important to note that while dogs can eat the same macronutrients as us, their recommended daily allowance varies considerably from our own. Deviating from this can result in medical complications.

Common Digestive Issues in Dogs

Our four-legged friends, unfortunately, can suffer from their fair share of digestive discomforts and ailments. Certain breeds are more afflicted, with overbred or inbred canines often being the most at risk.

Does your dog suffer from any of these common digestive issues?


Food allergies are incredibly common in canines, with Labradors, Dachshunds, Cocker Spaniels, and German Shepherds commonly considered the highest risk. There are a large number of possible allergens, but the most common are:

  • corn
  • beef
  • wheat
  • dairy
  • soy
  • eggs
  • pork
  • fish

There are a great deal of allergy-specific dog food options available today, with many owners being able to order food online that fits their dog’s specific requirements. In more extreme allergy cases, it may be better to provide your pooch with a full home-made diet; this can easily fit into busy schedules with advanced prep and freezing meals in bulk!

Irritable Bowel Syndrome in Dogs

Characterized by frequent diarrhea or constipation, dietary intolerances, and deficiencies, as well as high levels of anxiety, are common causes of IBS in dogs. Genetics can also play a role in determining vulnerability, with certain breeds more prone, including:

  • Basenji
  • Shar-Pei
  • German Shepherd


This ailment has seen a huge rise in the past decade, likely due to human table scraps in some dog's diets. Pancreatitis in dogs is another way of describing an inflamed pancreas, one of two reasons cause this inflammation, either the dog’s diet is too high in fat or endocrine disease.

This condition can be caused overnight by one high-fat meal. Therefore, it’s vital to monitor your dog’s food intake and any signs the dog's digestive system is upset. With the recommended fat intake for a 50-pound adult canine of 28 grams per day – that’s the equivalent of only three slices of cheddar cheese.

Examples of Human Food Dogs Can Eat

Now that you know all about the dog digestive system, canine-specific digestive issues, and how their diet has evolved, let’s take a look at some of the safe foods that your pup can eat. These foods can be incorporated into your dog's daily meals or given as snacks.

1. Watermelon

On a hot summer's day, feel free to throw a big slice of watermelon to Fido. Not only is watermelon safe for him to eat, but it also provides incredible hydration. For the owners out there who don’t feel as though their dog drinks enough, consider watermelon!

2. Berries

Another fruity favorite for the dog digestive system. One of the best pieces of hydration advice that I’ve heard of for dogs is to throw a few blueberries or raspberries into their water bowl. This will encourage him to fish around and drink more water on his quest to grab a tasty berry.

3. Oatmeal

Oats can be a helpful source of fiber and can help dogs with digestive issues. An excellent way to feed your dog oats is in a smoothie bowl. Make up a berry smoothie and top with some oats and honey for a delicious, healthful treat.

4. Peanut Butter

Dog Digestive SystemAs much as this is a must-have in our human diets, our dogs seem to share the taste for it. Peanuts are a well-known allergen in human diets, but a peanut allergy in canines is incredibly rare.

As with anything, test a small amount of peanut butter before going the whole hog. If your dog is picky about food, mixing a tablespoon of peanut butter into his meal can encourage him to finish his dinner.

5. Cheese

Of course, we couldn’t make a list without including a dog’s favorite human food – cheese. If your pup requires daily medication, hiding a tablet in a cube of cheese can be the easiest way to make sure he eats it.

The fat requirement for a dog is far less than that of a human, so be cautious about overfeeding cheese. Too much cheese in a dog's digestive system could cause constipation or increase Fido’s risk of developing medical conditions.

6. Eggs

These are best served scrambled, as raw eggs come with the risk of salmonella. Boiled eggs can be given but should be chopped up to remove the risk of choking. This is a particularly palatable option for dogs who are feeling under the weather.

7. Cooked White Rice

We’ve all heard of feeding dogs rice and veggies when they have an upset tummy, and the reason that many do this is that cooked rice is very gentle on the dog's digestive system. No need to make up an extra batch just for your dog if you’re cooking some anyway, but be sure not to salt the rice if you’re planning on sharing with your pet!

READ THIS: 9 Superfoods For Dogs That Improve Health (According to Science)

Examples of Human Food Dogs Cannot Eat

As there are foods that are good for the dog's digestive system, there are also foods that will cause digestive upset. In fact, some of these foods won't just upset the stomach – they could be toxic to your canine companion.

1. Grapes

These slippery little blighters are so easy to drop on the floor, but be sure to pick them straight up as they are toxic to our furry friends. Grapes and their dried counterparts, raisins, are both poisonous to dogs, but we don’t know why. Scientists have yet to determine the exact compound that causes this reaction, so it is best to just keep the grapes and raisins well away from Fido.

2. Onions and Garlic

Dog Digestive SystemWhite, red, and salad onions all contain the chemical thiosulphate, which, when ingested by a canine, causes hemolytic anemia. In layman's terms, hemolytic anemia is the destruction of the red blood cells.

It’s important to consider all “safe” leftovers before giving them to your dog, just in case onions are hiding within. Soups and sauces are a typical example of owners accidentally feeding their dogs onions. The same applies to garlic and anything in the onion family.

3. Chocolate

We all know that chocolate is a no-no for dogs, but do you know why? The chemical theobromine is present within this delicious treat, but while we humans quickly metabolize this – our pooches struggle to do so, allowing the chemical to build up in their system and, in severe cases, lead to internal bleeding, seizures, and eventually death.

Just one big Hershey’s bar can prove fatal to a Pomeranian, Chihuahua, or Maltese. And, just one bag of Hershey’s Kisses can be deadly for a Dachshund, Yorkshire Terrier, Mini Poodle, or Border Terrier.

4. Coffee

Caffeine is incredibly dangerous to dogs, and with the amount that we consume on a daily basis, either through energy drinks, coffee, or tea – our dogs are at risk of being exposed.

For smaller breeds, the risk is greater as it takes less to cause severe poisoning. In fact – a little dog grabbing a couple of mouthfuls of coffee grounds out of the trash can be enough to kill.

5. Xylitol

This plant-based sweetener is being seen in more and more human foods due to its incredible sweetening powers while being better than plain old sugar. Even tiny amounts of Xylitol can cause hypoglycemia in canines, which can lead to seizures, liver failure, and even death.

6. Bacon

I’m sure that many owners think that it's nice to throw their begging dog a piece of bacon. But, as bacon is so high in both fat and sodium, it can cause extreme medical problems for your dog, including pancreatitis, coma, and seizures. At a minimum, bacon will upset the dog's digestive system, causing gas, bloating, or diarrhea.

7. Whole PeachesDog Digestive System

Fruits with pits, such as peaches and plums, can be deadly to dogs in one of two ways. First, the pit can cause a blockage in the small intestine, and second, the pit of peaches contains cyanide. This is fine for humans because we don’t eat the pit, but your dog might get carried away and end up poisoning himself.

READ MORE: 7 Worst Human Foods for Dogs (Based on Studies)

Dog Digestive System Final Thoughts

Whether we’re talking about the human or dog digestive system, the food that you put in directly correlates to the level of health you can expect to achieve.

As a dog owner, it’s your responsibility to make sure that your dog gets everything he needs and steers clear of anything that can cause him harm. Understanding how your dog's digestive system works and what dogs can digest and what dogs cannot digest can help immensely.

It may sound like a heck of a responsibility, but as with anything, it just takes a little bit of effort to do the research and reading on how to feed your canine to accommodate your dog digestive system, and you’ll be in the swing of it in no time.

READ NEXT: 15 Best Sensitive Stomach Dog Foods for Upset Stomachs

There are plenty of commercial dog food brands, homemade dog food recipes, and healthy canine-appropriate human foods that are very safe and healthy for dogs to consume and may benefit their overall health and help digestion.

As long as you make sure that the food you're feeding your Fido won't upset the dog's digestive system, you're likely not only to keep your pet in tip-top shape but even extend his lifespan, and the rest will come as you educate yourself about your pet's unique needs.

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Dog's Digestive System Breakdown (and what dogs can and cannot digest)

Nadia is a Canine and Equine expert and has been professionally writing about her two favorite animals for over ten years. Her passion and knowledge most notably within the areas of training, health, and welfare of dogs and horses.