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  • Hahnbee Choi, Cert. CN

Digestive Enzymes | The What, How & Why

Updated: Jul 14, 2022

Digestive enzymes are responsible for breaking down carbohydrates (polysaccharides), proteins (polypeptides), and fats (lipids) which allow nutrients to be broken down and absorbed into the body. Enzymes are created in the pancreas and released into the intestine after eating. But whether a kibble-fed dog, a transitioning dog, or a food-sensitive dog, supplementing with digestive enzymes can have its place. Here is all you need to know about digestive enzymes.

The primary digestive enzymes are:

  • Lipase: for fat

  • Protease: for protein

  • Amylase: for starches

The Digestive System - Overview

A brief overview of the digestive system is needed to understand how digestive enzymes work. First, the food is picked up and broken up slightly through chewing. Then, with lubrication from mucus, it is swallowed. This is where omnivores and herbivores begin to digest carbohydrates, but this does not happen in carnivores as the food is in the mouth for a very short amount of time. The food travels down the esophagus with the help of stratified squamous, which protects the pathway from any damage that may occur. Contractions push the food down the tube to the stomach. The stomach is C-shaped and coated with protective mucus. In the mucosa, there are gastric pits that have 3 main types of cells responsible for gastric juices:

  • Goblet Cells: which secrete mucus to lubricate the food and stomach lining from being eaten by digestive enzymes.

  • Chief Cells: secrete pepsinogen, the precursor to the active enzyme pepsin that breaks down proteins into peptides.

  • Parietal Cells: They create Hydrochloric Acid (HCI), which makes a very acidic pH that allows pepsin to work correctly.

Food is broken up and partly digested in the stomach, resulting in a pulpy acidic fluid called chyme. Chyme is released in spurts and then passes into the duodenum. The duodenum is the first part of the small intestine. The small intestine is the central setting for enzymatic digestion and absorption. The food makes its way down the small intestine, which is around 3.5 times the body length depending on the animal. It then mixes with digestive juices through peristalsis (involuntary constructing and relaxing, creating wave-like movements).

The small intestine has 3 parts:

  • The Duodenum: A U-shaped tube with the pancreas lying in the loop of the “U”. The common bile duct (gallbladder), which contains bile salts needed for fat digestion, opens into it. Brunner’s glands in the walls secrete a mixture of digestive enzymes (succus entericus). The duodenum then leads to the Jejunum.

  • The Jejunum/Ielium: Hard to tell apart; this is a long tube with a free form that allows it to expand in any peritoneal cavity. In the walls, there is a digestive gland called the crypts of Lieberkuhn.

Each part of the small intestine is similar in that the epithelial layer is folded, so villi, tiny leaf-shaped folds, can increase the surface area to increase efficiency to digest and absorb nutrients.

Then it travels to the large intestine. This is a short and broader tube than the small intestine. It also has no villi or digestive glands as its job is to absorb water, electrolytes, and water-soluble vitamins and finally excrete waste. The large intestine can be divided into 4 pieces:

  • Caecum: A short tube joining the ilium. In carnivores, this has no function, but it stores food material where bacteria can break down cellulose in herbivores.

  • Colon: Here, the water, vitamins, and electrolytes are absorbed, ensuring the body does not lose water.

  • Rectum: Temporary storage for feces and runs through the pelvic cavity and is held in place by connective tissue and muscle.

  • Anal Sphincter: The end of the digestive tract and controls feces.

What are enzymes?

Enzymes are proteins that act as catalysts increasing the speed of a reaction. Certain enzymes may be an inactive form (a precursor) that first needs to convert to be an enzyme’s active form. Each enzyme is created to act on a specific material or substrate. The enzyme names usually come from their substrate, such as lipase acting on lipids and maltase acting on maltose. There are 4 digestive juices containing enzymes: gastric juices, pancreatic juices, bile salts, and intestinal juices. For carnivores, enzymatic digestion begins in the stomach.

Gastric Juices - secreted through the gastric pit in response to the hormone gastrin from the stomach wall.

  • Mucus: Lubricates the food.

  • Hydrochloric Acid (HCI): Denatures proteins and creates an acidic environment that makes digestion easier.

  • Pepsinogen: Converted to the active enzyme pepsin for HCI. Pepsin converts protein molecules to peptides through hydrolysis.

Pancreatic Juice - Occurs due to hormones cholecystokinin and secretin (wall of the duodenum) and gastrin (stomach wall).

  • Bicarbonate: neutralizes acid on chyme allowing other enzymes to work.

  • Digestive Enzymes: many precursor enzymes are released to avoid autodigestion and destroying the pancreas.

  • Protease: acts on proteins and also include

  • Trypsinogen: convert trypsin to another enzyme

  • Trypsin: activates other enzyme precursors. Acts on peptides and proteins to produce amino acids.

  • Lipases: Activated via bile salts. Convert fat to fatty acids.

  • Amylase: Converts starches to maltose.

Do I need to supplement digestive enzymes?

As shown above, digestion already has a lot of naturally occurring enzymes so a healthy dog will not need additional supplementation. But sometimes supplementation can be of benefit. Below is a guideline for when digestive enzymes can be of aid.

Health issues related to digestive enzymes:

  • Exocrine Insufficiency (EPI): a condition where the pancreas fails to produce enough enzymes to digest food.

Beneficial to feed:

  • Times of digestive upset

  • Transitioning onto a new food

  • Acid reflux

  • Diarrhea

  • Constipation

  • Gassy pet

  • Kibble-fed dog


The FDA does not regulate digestive enzyme supplements, so the dosage and ingredients are not always guaranteed. Look for supplements with animal sources, the most popular choice being Pancreatin 10X.

Other quality supplements include:

Digestive enzymes are not essential to feed but adding this addition at the right time can help your pup out. As always, I hope you learn something new today & Always Keep Exploring!


“Digestive Enzymes and Digestive Enzyme Supplements.” Johns Hopkins Medicine,

Aspinall, Victoria, et al. Introduction to Animal and Veterinary Anatomy and Physiology. CABI, 2020.

“Gastric Pits.” Gastric Pits - an Overview | ScienceDirect Topics,

“Glossary.” Linus Pauling Institute, 20 Dec. 2021,

Suzuki A, Mizumoto A, Sarr MG, et al. (1997) Bacterial lipase and high-fat diets in canine exocrine pancreatic insufficiency: a new therapy of steatorrhea?Gastroenterology112, 2048–2055.

Enzyme Activators | Harvard Catalyst Profiles | Harvard ...

“Peristalsis.” Peristalsis - an Overview | ScienceDirect Topics,
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