Dog Digestion: Everything You Need to Know

A healthy digestive system is essential, for humans, as well as for our canine companions. We spend a great deal of time concerned with what our dogs are eating and whether or not their bowel movements are normal—especially since we are the ones cleaning it up!

But we rarely pause to think about dog digestion and what comprises our dog’s digestive system. How it is different from our own? How long it takes for our dogs to digest food? Are there foods our dogs cannot digest?

One of the best and simplest ways to monitor our dog’s health is to keep an eye on their digestion. Here’s some more information about your dog’s digestive system and what you should know to keep everything running smoothly. 

Understanding the Dog Digestive System

The entire process of digestion is the result of many organs, enzymes, and systems.  The canine digestive system is similar in structure to that of a human, but there are notable key differences to the way our dogs convert food into usable energy. 

Think of the dog digestive tract like a long tube that begins with the mouth and esophagus, proceeds to the stomach, then the small and large intestine, and finally to the rectum. Although the liver and pancreas are not directly along the digestive tract, they are essential organs that help aid digestion and process nutrients. 

Digestion occurs in some form or another at every portion of the dog digestive tract, and digestion would not be possible without each and every component. With the exception of the mouth and esophagus, the entire digestive tract is inside your dog’s abdomen, where the majority of digestion and nutrient absorption occurs.  

How Do Dogs Digest Food?

To better understand the dog digestive system and how digestion occurs, it is easiest to group it into four categories: the mouth and esophagus, the stomach, the small and large intestine, and the accessory organs.  

Mouth and Esophagus

When your dog eats food, this act kicks off the digestive process. Food is brought into the mouth by the front teeth and lips, then pushed to the back of the mouth by the tongue where it is ground up by the molars and swallowed. 

Dogs have forty-two teeth, whereas humans only have thirty-two. Therefore, dogs can complete this step more quickly and efficiently than we can. It’s often impressive (and a bit alarming) when our dogs eat two cups of food in under sixty seconds!. 

Chewing food, or masticating, breaks it into smaller particles and mixes it with saliva so  it can easily slide down the esophagus. A dog’s esophagus is a muscled, hose-like tube which passes through the neck and chest to the stomach. Unlike human saliva, dog saliva lacks digestive enzymes. Dog saliva primarily serves as a lubricant to help the chewed up bits pass from the mouth through the small esophagus and into the stomach without becoming stuck along the way.  

Stomach

Enzymatic digestion begins in the stomach for dogs. A dog’s stomach is a thick-walled, sac-like structure composed of smooth muscle. The interior surface of the stomach contains a series of gastric folds, which help grind and break down food, and the lining secretes hydrochloric acid, protein-digesting enzymes (proteases), and mucous to turn the ingested contents into a liquidy mush, called chyme.  

In dogs, the stomach stores food in addition to breaking it down. Food is reserved in a dog’s stomach for up to 8-12 hours. In contrast, food passes through a human’s stomach in as little as 30-90 minutes. 

Our dog’s ancestors sometimes went long periods of time without eating, so they would eat as much as possible when the opportunity presented itself. As a result, a dog’s stomach can stretch to allow for storage of food, and the muscular organ releases food into the small intestine in a regulated manner. This provides the dog with the unique advantage of being able to save and store food for when it’s needed. 

Small and Large Intestine

Once the food has been adequately liquidized into an easily digestible chyme, it moves into the small intestine where the food can be absorbed and processed. 

The first portion of the small intestine is called the duodenum. This early portion of the small intestine contains ducts leading from the pancreas, gallbladder, and liver, which contribute the final digestive enzymes. Additionally, the acid level of the chyme is reduced to prevent damage to the remainder of the gastrointestinal tract.

Next, the food enters the longest and second segment of the small intestine, the jejunum. This is where the food—now processed by acid, enzymes, and mechanical breakdown—undergoes nutrient extraction and absorption. The jejunum is lined with thousands of small, finger-like projections called villi, which draw out the nutrients and transport them across the intestinal lining to the bloodstream for use within the body.

Leftover waste, now devoid of nutrients, moves on to the last and shortest section of a dog’s small intestine, the ileum, which connects the small and large intestine.

The large intestine is the beginning of the colon in dogs. Moisture is removed from the remaining, unneeded, or unusable material, as it moves through the colon forming firm, fecal material. Any lingering minerals are also extracted here. The final product then exits the body through the rectum, and finds it way into your poop bag or scoop.  

Pancreas and Liver

Although the pancreas and liver are not directly a part of the dog digestive tract, they are essential for proper food digestion and preparing nutrients for absorption.

The pancreas contributes juices full of enzymes and hormones that are critical for digestion. These pancreatic juices enter the tract at the duodenum. The enzymes are responsible for breaking down fat, proteins, and sugars so they can be absorbed in the jejunum. Pancreatic hormones, primarily insulin, help regulate a dog’s blood sugar levels and appetite, stimulate stomach acid production, and signal stomach emptying. 

The liver makes bile, which is stored in the gallbladder, and added to the chyme in the duodenum. Bile is needed to properly digest fats and utilize them within the body.  Additionally, after nutrients are absorbed from the jejunum, most of them wind up in the liver, where they are processed for utilization throughout the body. 

How Long Does It Take for a Dog to Digest Food?

On average, it can take anywhere from 8-12 hours from the moment food enters your dog’s mouth until you see it again on the other end. This is about three times less than the amount of time humans take to digest a meal.  

The rate and efficiency of canine digestion depends on a combination of the following: 

Your dog’s breed. The breed of your dog often determines your pet’s size and weight, and has the greatest effect on the rate of their digestion. A dog’s digestive tract is roughly three times as long as they are, therefore, there is a direct correlation between the size of your pet and the length of their gastrointestinal tract. Larger dogs have a longer tract, so it takes food more time to move through.

Your dog’s age. Age has the second greatest effect on the time it takes for a dog to digest food. Puppies have the highest energy requirements, and therefore, need to eat and digest food on a more regular basis. Since they need a constant fuel supply for growth, food will not be stored in their stomach nearly as long as in adult canines. In a similar manner to humans, a dog’s metabolism will slow with age. Digestion becomes a lengthier process each year of your dog’s life. Senior dogs may chew more slowly, due to dental issues, and they will also digest food more slowly once it enters their stomach. In most cases, these age-related changes are not obvious to owners or clinically significant.

Your dog’s activity level. Very active dogs will digest food more quickly. They expend more energy, and therefore, must replace the fuel they used by consuming more and digesting quickly. Sedentary dogs, who have little energy output, will not need to digest food as rapidly, and it will linger for a greater amount of time in the stomach. Senior dogs are often less active than younger dogs, further contributing to their slow rate of digestion.

Your dog’s hydration level. Water consumption and adequate hydration speed up the digestive process. Increased hydration helps with enzyme secretion, saliva and mucous production, and keeps everything slipping along the tract appropriately.

Your dog’s food type. The type of food you feed your dog also determines how quickly it will pass through a dog’s digestive tract. Wet or canned food will move through more quickly than dry food. Furthermore, the more fibrous or firm the material, the longer it will take for it to pass from the stomach into the small intestine. 

Your Dog’s Digestive System: A Look at Certain Foods

As previously mentioned, some foods are easier to digest than others, and although our pets sometimes think they can eat anything, there are definitely limitations.  

Veterinarians are commonly questioned about ingested materials such as chicken bones, rawhide treats, corn, grains, and eggs, and whether our dogs can digest them.

Can Dogs Digest Chicken Bones?

The highly acidic environment of a dog’s stomach does make the digestion of small chicken bones and fragments possible. However, that does not mean that dogs should eat chicken bones! In fact, most veterinarians advise against dogs eating chicken bones. Chicken bones—or any bones for that matter—are not easily digested, and pieces that are too large can become lodged in the narrow tube of the small intestine, causing a mechanical obstruction, which is a life-threatening condition that requires surgery. Even small bones can be potentially problematic, as they can splinter into sharp fragments which can puncture through the gastrointestinal tract, causing peritonitis, an abdominal infection. Sharp pieces can also scratch or irritate the sensitive internal linings of the tract leading to severe gastrointestinal upset. 

Additionally, chewing on bones or antlers is the most common cause for chipped or broken teeth in dogs. Broken teeth are painful and can lead to a tooth root abscess if left untreated. Bear in mind that dental repair in dogs is quite expensive without insurance.  

Can Dogs Digest Rawhide?

Rawhides are commonly given to dogs as a reward and an outlet for their desire to chew. These treats are created from dehydrated cattle hides and often flavored with chicken or beef for palatability.  

Just as with bones, it will take these thick, fibrous treats more time to digest than regular food, but technically, yes, they can be digested. While small pieces of rawhide will eventually travel through the digestive tract without causing issues, larger chunks could lead to intestinal blockage.  

If you are a dog owner who gives your dog rawhides, be sure to supervise them and ensure they aren’t breaking off and swallowing large pieces.  

Can Dogs Digest Corn?

It has been said that corn is a “filler” in dog food, however, corn is not only acceptable in a dog’s diet, but also beneficial to their health. Corn is a great source of many nutrients such as protein, carbohydrates, linoleic acid, and antioxidants.  

Corn must be cooked or processed first in order to remove the cellulose husk that animals, including humans, cannot digest. Once the outer shell is removed, corn is readily and easily digested. If the cellulose shell is not removed,  it will simply pass through the digestive tract unchanged, and will not cause any issues.  

Corn cobs, however, are not digestible and can easily become lodged in the esophagus or small intestine, so they should never be fed to dogs. 

Can Dogs Digest Grains?

Despite rumors that dogs cannot or should not eat grains, the truth is that dogs actually digest and metabolize grains efficiently, especially when they are pre-cooked. In fact, wild dogs and wolves eat grains regularly! One of the most sought after rewards from their herbivorous prey are the stomach and gastrointestinal linings, often full of grains and roughage. 

Carbohydrates from grains provide your dog with readily available energy thereby sparing precious protein needed for other essential bodily functions. In addition, carbohydrates provide a good source of fiber, which promotes gut health and motility, and essential nutrients such as protein, fat, fiber, and vitamins.  

Can Dogs Digest Eggs?

Eggs are high in easily digestible protein and contain many essential fatty acids. Dogs can digest eggs both in their cooked form and raw form—shell and all! However, feeding raw eggs to dogs poses the same risk of foodborne illnesses that feeding raw meat does, so it is recommended that eggs be cooked before being fed to our pets.  

Avoid using spices, seasonings, butter, or oil while cooking eggs for dogs, as those ingredients can lead to gastrointestinal upset. Also, take care not to overfeed eggs, as too many can lead to high cholesterol and other nutritional imbalances. If you’re not sure how much is too much, reach out to your veterinarian. 

Caring for Your Dog’s Digestive System

Now that you have an understanding of the anatomy and processes behind digestion, use these tips to keep your dog’s digestion in top shape.  

Consider probiotics. Give your dog a daily probiotic supplement to keep their digestive tract functioning optimally. There are many different probiotic supplements specifically formulated for dogs. Contact your veterinarian for guidance selecting a product for your pet if you feel overwhelmed. 

Don’t use unnecessary digestive enzymes. Avoid supplementing your dog with digestive enzymes unless instructed by your veterinarian for treatment of a medical condition. Your dog’s digestive tract is already equipped with the enzymes necessary for flawless digestion, and additional supplementation could lead to imbalances. 

Keep an eye on your dog’s stool production. Dogs should defecate at least twice daily depending on frequency of meals and lifestyle. A combination of lack of dietary fiber, inadequate hydration, or more could be negatively impacting your pet’s digestive rate. 

Occasional loose stools or diarrhea are not alarming, but if your dog’s feces are typically wet, you should consult a veterinarian to screen for digestive issues. Ongoing diarrhea can lead to dehydration, loss of nutrients, and weight loss. 

Refrain from sharing greasy table foods. Refrain from sharing any greasy or fatty human food with your canine companions. Bacon grease, french fries, potato chips, or lots of cheese can overwhelm the digestive system and lead to serious illnesses like pancreatitis.

Feed a diet that is appropriate for your dog’s life stage. Puppies have different nutritional requirements than senior dogs. Take your dog’s life stage into account when selecting a diet, ensuring that you choose a diet that meets your dog’s unique nutritional needs.

Abnormal Dog Digestion: What to Do

A basic understanding of your dog’s digestive system will help you identify and avoid digestive issues before your dog becomes seriously ill. 

If your pet routinely experiences digestive upset, ask about a prescription dog food. These diets are uniquely formulated with fiber, protein, and fat ratios ideal for proper digestion.  

But if you notice any abnormalities or something seems off, it’s important to see a veterinarian. Digestive issues can have a wide variety of causes, and the most common causes of digestive issues may vary depending on your dog’s age. Together, you and your veterinarian can identify the cause of your dog’s digestive issues and create the best plan to keep your dog in top health.