The front end of a dog’s digestive system encompasses the mouth, esophagus, stomach and small intestine. Dog digestion begins almost immediately with saliva in the mouth. You may have wondered why dog tongues are so slobbery. Since they spend less time chewing food than humans tend to, all of that saliva kickstarts the process of breaking down and coating food particles for smoother passage through the esophagus. The esophagus is heavily muscled, actively pushing food into the stomach.
Part 2: A fantastic journey through the small intestine
A dog’s stomach is a super-acidic environment, which is useful for opportunistic omnivores, helping them more easily digest things like bone and raw meat. Yes! Dogs can digest bones! Here, solid food is rendered into a substance called chyme, which is made up of food, water, and acid. All food — from your Michelin 3-star-rated fine cuisine, to your dog’s canned chunks or dry kibble — ends up as this highly acidic gloop. As this chyme proceeds into the small intestine, the real work of digestion — the isolation of nutrients that can be used by the body— is done.
There are three parts of food’s journey through the small intestine. In the first part, the duodenum, chyme is treated with enzymes and hormones from the liver and pancreas, which reduce the acid level of the chyme. The gloop is now prepared to have the rest of its nutrients extracted and absorbed. This happens in the second part of the small intestine, which is called the jejunum. This part of a dog’s small intestine is basically covered in little probes, which, like fly paper, pick up and absorb useful nutrients into the bloodstream.
Part 3: The large intestine and waste removal
The final part of the small intestine is the ileum, which absorbs whatever nutrients remain. By this point, the once-acidic chyme gloop is now a sort of thicker pasty substance. You’d be surprised how little of the food you or your dog eats is actually used by your body. Did you ever wonder why your dog’s digestive system produces so much poop? It’s because the actual nutrients — proteins, vitamins, fats and so on — that your dog’s body can utilize are miniscule in proportion to the physical volume of most dog food.
How long is this part of a dog’s digestive system? It varies by size. If you stretched out a dog’s small intestine, it would be nearly three times as long as the dog. The back end of a dog’s GI tract is fairly short by comparison, just over a foot long, give or take, depending on the dog. Its primary components are the large intestine and the anus. The large intestine is basically a water remover and garbage compactor. Having spent the first half of its journey being mashed up, dissolved and sifted, any parts of a dog’s meal that cannot be used is treated by bacteria, and reconstituted into a solid package we call poop.
