How Does Dog Digestion Work? Find Out!

A dog's digestive tract has many similarities to a human's. It begins in the mouth and ends at the anus. It includes the oral cavity, the esophagus, the stomach, the small intestine, the large intestine, the rectum, and the anus.

Also, the pancreas, gallbladder, and liver help with digesting and absorbing food. The canine digestion process is similar to a human's, with some differences stemming from the characteristics of their diet.

The Canine Diet

If dogs could choose their favorite food, they'd go for fresh meat. They're mainly carnivorous, and as such, their body is adapted to optimize the nutrients they get from this diet. But, today they behave as omnivores, able to eat very different foods, including fruits and vegetables.

To understand how a dog's digestive system works, we can't lose sight of its past. To do this, it helps to think of a wolf pack. So, a dog's gastrointestinal system is designed to eat occasionally, but ingesting large amounts of food at once.

The Mouth

Dogs are predators, and at the first level of the digestive system, the mouth, they have teeth adapted for killing prey and tearing its meat. Also, saliva makes swallowing easier, providing lubrication and compaction. It also keeps the mouth clean. Dogs have fewer taste buds than humans.

Specifically, around 2,000 compared to our 12,000. Because of this, they perceive fewer flavors. They can tell apart sweet, sour, bitter, and salty. The teeth, tongue, and jaws also contribute to initial food processing, though digestion barely begins in the oral cavity.

The Esophagus

Food passes almost unchanged into the esophagus, which expands and contracts rhythmically to let food through before it reaches the stomach, which acts as a large tank. The esophagus is a membranous, fibrous tube also notable for its elasticity, letting large chunks of food pass through.

Unfortunately, this structure also makes it easier for foreign objects, like bones or toys, to pass through along with food — these sometimes fail to be expelled and can cause an obstruction.

The Stomach

Ingested substances can stay here for up to eight hours. The cardia is the sphincter that lets food through. It opens and closes tightly. The upper part of the stomach is called the fundus, and it's where acids are produced to break down connective tissue and muscle fibers.

An acid that starts breaking down proteins is also secreted. Enzymes produced by the pancreas and liver contribute to digestion. Also, glands in the stomach secrete mucus to prevent acids and enzymes from damaging the stomach and intestinal walls.

During digestion, proteins, carbohydrates, and fats from food are broken down into simple molecules that can be absorbed and, therefore, used by the body. During this process, peristaltic movements occur, mixing food and moving it toward the small intestine.

The Pancreas

The pancreas produces alkaline bicarbonate to neutralize stomach acid, along with digestive enzymes that break down proteins, carbohydrates, fats, elastic and connective tissue, and even nucleic acids. These enzymes pass through the pancreatic duct into the common bile duct and enter the intestines along with bile.

Also, some areas of the pancreas produce insulin, responsible for letting glucose enter every cell in the body. Without insulin, cells can't access glucose.

It'll build up in the blood. Insulin deficiency is called diabetes and causes symptoms like increased water intake or urination. So, insulin is essential for a dog's body to function properly.

The Liver

The liver produces bile, which helps break down fats. Specifically, the gallbladder stores bile acids. It concentrates bile and, during digestion, transports it through the common bile duct to the duodenum.

Bile acids are responsible for emulsifying fats. They also help dissolve fat-soluble vitamins. Also, nutrients are turned into energy reserves in the liver.

The Intestines

Nutrient absorption happens through the small intestine's walls. They're then carried in the blood to cells throughout the body. The duodenum is the first part of the small intestine. Finally, waste — meaning the remains of unused food — reaches the large intestine or colon, which has a much larger diameter.

Water and salts are absorbed in this part of the digestive system. A large number of bacteria forming the gut flora, microflora, or microbiota live in the colon. These perform functions beneficial to the body. They synthesize vitamins, break down waste material, or reduce the body's susceptibility to infections.

They leave the stomach when the pyloric sphincter, or pylorus, relaxes. Roughly 36 hours after eating, this waste turns into feces. Rectal distension prompts the dog to defecate, expelling it through the anus.

Bibliography Carlson and Giffin. 2002. Dog Owner's Home Veterinary Handbook. Madrid: Editorial el Drac. Fogle, Bruce. 1995. The Encyclopedia of the Dog. London: Dorling Kindersley Limited.