Dog digestion and feeding

After writing my myths BUSTED post, I began thinking about how often I am asked about what I feed my greys. I felt that this topic is worth spending more time discussing.

 First let’s discuss the gut of a dog. All mammal digestion begins in the mouth. This is where we begin to break down the particles in our food to extract the important elements needed for sustained life. Most mammals produce amylase, an enzyme that breaks down carbohydrates, in their saliva. Amylase is not produced in a dog’s saliva.

We must remember that our sweet cuddly greyhounds are natural born predators that are more than able to crush through bone and muscle meat with ease. Carbs were not often on the menu.  Open up her mouth and check out those huge teeth!

After reading this about amylase I was confused as to how dogs break down kibble. Let’s dive into the dog’s GI tract to learn how this happens.

After your hound ravenously devours her food, she swallows it. The esophagus allows the passage of food from the mouth to the stomach. The esophagus is just a connection, nothing exciting happens here.

Then the food enters the stomach. Dogs have single chamber stomachs like humans. The stomach pH of a dog is about 2, which is the same acidity as lemon juice.  The strong gastric acid combined with the muscle strength of the stomach begins to break down food into absorbable molecules- but minimal absorption actually occurs in the stomach.

Once the food has been broken down by the gastric acid, the food enters the small intestine. Mammals have three parts that make up their small intestine: the duodenum, jejunum, and the ileum. The small intestine is a large organ and can be about two and half times the dogs total body length!

The duodenum is the smallest part of the small intestine but the most important. The duodenum connects the small intestine to the stomach. While food is in this section it is combined with enzymes from the gallbladder, pancreas, and liver. The duodenum is where amylase, lipase, and proteinase begin to break down carbohydrates, fats, and protein, creating the building block for life.  In the duodenum, kibble is broken down.

After the food is further broken down, it enters the jejunum. The jejunum is the longest section of the small intestine. The jejunum has a large surface area to allow for absorption of nutrients.

After the jejunum successfully absorbs all important nutrients from the food, the remaining intestinal contents are released into the ileum. The ileum connects the small intestine to the large intestine.

Once the intestinal contents reach the large intestine most nutrients have been absorbed and broken down. The job of the large intestine is to absorb water and create feces. The large intestine is critically important in the hydration status of the dog. Once most water is absorbed, the feces enters the anus and then rectum. Once in the rectum the dog will be able to expel its waste.

Feeding

When I first read that dogs do not have amylase in their mouth I felt that raw food was the only way to feed a dog.  Since learning more about dog digestion and monitoring my dogs on raw my opinion has somewhat changed.

I have three greyhounds. They were fed raw for about three years. I have followed both the BARF (bones and raw food) method and whole prey.  I feel that whole prey worked better for my dogs and aligned with my concerns regarding no amylase in dog saliva. I used multiple protein sources and felt very good about the diet they were receiving.

 

I researched this more, reading accounts on what Henry VIII fed his hunting greyhounds, what open field coursing greyhounds are fed, and what top US racing greyhounds eat.  A theory for feeding carbohydrates continued to surface throughout my research; it stated that greyhounds need a lot of ready-to-use energy for sprinting. The carbohydrates in kibble, pasta, and rice that trainers often feed help with this. The balance between the raw protein source and the kibble create a balanced diet for quick acceleration from an energy standpoint.

I encourage greyhound owners to try different diets and see what their hound thrives on. There are easy options for raw and kibble. The most important thing to remember when choosing a food it how you dog looks, feels, and preforms on that diet.  After all a dog’s diet is not a bragging point between humans but an elemental point of existence for your hound.

The illustrations in this post are reprinted with permission by the copyright owner, Hill’s Pet Nutrition, from the Atlas of Veterinary Clinical Anatomy. These illustrations should not be downloaded, printed or copied except for personal, non-commercial use.