Digestive Enzymes in Dogs: Amylase, Protease, Lipase and More

Food contains many different types of molecules.

Starch is chemically different from protein. Protein is different from fat. Plant cell walls contain yet another collection of complex carbohydrates.

No single digestive enzyme can break all of these materials apart.

Instead, digestion depends on specialised enzymes, each capable of acting on particular chemical bonds or substrates.

The big question is:

What do the different digestive enzymes actually do, and why does the type of enzyme matter?

The main enzyme activities relevant to this discussion can be considered individually.

Amylase

Amylase acts on starch.

Starch consists of long chains of glucose molecules. Amylase helps break particular bonds within those chains, producing smaller carbohydrate fragments that can be processed further.

Dogs produce pancreatic amylase naturally, and pancreatic secretions release it into the small intestine.

Protease

Protease is a broad term for enzymes that break peptide bonds within proteins.

Protein digestion begins in the stomach and continues extensively within the small intestine through pancreatic and intestinal enzyme activity.

The result is progressively smaller peptides and amino acids that can ultimately be absorbed.

Lipase

Lipase acts on dietary triglycerides.

Fat digestion depends on the interaction between bile and lipase activity.

Bile helps disperse fat into smaller droplets, increasing the surface area available to enzymes.

Pancreatic lipase can then break triglycerides into smaller lipid components that can be absorbed through the intestinal lining.

Fructanase

Fructans are carbohydrates made largely from chains of fructose.

Fructanase describes enzyme activity capable of breaking bonds within fructan molecules.

Dogs do not rely on fructans as a major direct source of glucose in the way they can digest starch. Fructans that remain intact can therefore become substrates for microbial fermentation further along the gastrointestinal tract.

Cellulase

Cellulose is a major structural component of plant cell walls.

Mammals do not produce substantial endogenous cellulase activity, so cellulose is not digested by the dog's own enzymes in the same way as starch.

Cellulase breaks bonds within cellulose molecules, producing smaller carbohydrate fragments.

Xylanase

Xylans are hemicellulose carbohydrates found within plant cell walls.

Xylanase breaks particular bonds within these structures.

Like cellulose, xylan is different from starch and requires different enzyme activity for degradation.

Beta-glucanase

Beta-glucans are glucose polymers with chemical bonds that differ from those found in starch.

Beta-glucanase acts on these beta-linked carbohydrate structures.

Beta-glucans occur naturally in cereals including barley and oats, as well as in other biological materials.

Phytase

Phytate is a storage form of phosphorus found particularly in seeds and cereal grains.

Phytase removes phosphate groups from phytate.

This can alter the chemical form in which phosphorus and associated minerals are present within a food matrix.