Digestive enzymes in dogs and cats

Supplementing with digestive enzymes can enhance the health and well-being of our canine and feline patients in many crucial ways.

“Man is not nourished by what he swallows, but by what he digests and uses,” wrote Hippocrates. This is true for all creatures, including dogs and cats – and an important part of what determines that nourishment involves digestive enzymes.

Two enzyme categories

1. Metabolic enzymes are present in every cell, tissue and organ in the body, and act as biochemical catalysts in the moment-to-moment function of living cells. They are responsible for keeping the body in proper balance by controlling virtually every chemical reaction associated with metabolism. Because of this, metabolic enzymes are the very basis of the life process.

2. Digestive enzymes, the primary focus of this article, can be separated into intrinsic and extrinsic enzymes. Intrinsic digestive enzymes are those the body manufactures and secretes to break down food. The salivary glands in the mouth, the gastric glands in the stomach, and specific cells in the pancreas secrete the enzymes that work to digest the proteins, fats and sugars in any food. Examples of extrinsic digestive enzymes are protease, which digests protein; amylase, which digests starch; and lipase, which digests fat.

Normal physiology of digestive enzymes

Most fresh-grown food contains enough active enzymes to digest the proteins, starches or fats found in that food. For example, avocados and nuts have naturally-occurring lipase or fat-digesting enzymes, while oats have a high level of amylase, or starch-digesting enzymes. The contribution of food-based enzymes to the digestive process is extremely important and too often overlooked.

The food should enter the stomach complete with digestive enzymes, which pre-digest the food. The stomach churns the food, pre-digesting as much as 75% of the meal. This process varies in time with any given species, after which hydrochloric acid, produced by the parietal cells in the stomach wall, is introduced, temporarily inactivating all the food-based enzymes and breaking down what is left of the meal. Then, acid-resistant pepsin is introduced.

Enzymes, even though they are proteins, are too big and complex to be destroyed by the acid in the stomach, which means they can’t be digested. Most enzymes are rendered temporarily inactive by the high acid environment, then reactivated the moment they enter the more alkaline environment of the intestinal tract.

Eventually, the nutrient-rich food concentrate moves into the duodenum, where enzymes produced by the pancreas are responsible for the final digestion of proteins, carbohydrates and fats. Liver secretions neutralize the acidity of the gastric juice and bile emulsifies the fats for better digestion and absorption. Nutrients are absorbed along the surface of the intestine and carried into the blood, which flows to the liver where it is filtered to prevent the circulation of undesirable substances in the body. Nutrients are then delivered to every cell of the body. Finally, waste products, undigested food and bacteria move into the colon to be eliminated.

What is an enzyme?

Enzymes are proteins found either within cells or dissolved in the mesenchyme and body fluids. They serve as biological catalysts, reducing the amount of energy required for chemical reactions, and controlling metabolic reactions that would otherwise either not take place, or occur very slowly, under normal physiological conditions. There are over 80,000 known enzyme systems, each with a specific function. Life would not exist without them, as the body’s entire metabolic process is based on the activation, inhibition and control of enzymes.

Supplemental enzymes

Supplemental enzymes are needed to replace those destroyed by cooking and processing food. Processing and cooking  at  any heat of approximately 118°F to 129°F (48°C to 54°C), for as few as three minutes, can destroy virtually all enzymes,1 which results in very little pre-digestion taking place in the stomach. Thus, what’s left of the food mass enters the small intestine largely undigested. This puts the pancreas and other organs of the endocrine system under tremendous stress, since they have to draw reserves from the entire body in order to produce massive amounts of the proper enzymes.

Supplemental enzymes are often found in combinations:

  • Lipase: Fairly acid stable, digests most fats.
  • Lactase: Digests milk sugar. Most mammals have high intestinal lactase activity at birth, which declines to low levels with age, and causes incomplete digestion of milk and other foods containing lactose. Like humans, some dogs and cats seem more capable of tolerating milk than others; and there is a significant difference in lactose levels between milk products, ranging from zero in cheddar cheese, to 11 grams in a cup of whole milk.2
  • Amylase: Aids the breakdown and assimilation of starches and carbohydrates so they can be converted by other enzymes to glucose.3
  • Glucoamylase: Breaks down maltose into glucose molecules.4
  • Cellulase and hemicellulase: Break down cellulose (fiber), which allows access to key nutrients in fruits and vegetables (e.g. carotenoids in carrots, polyphenols in berries, enzymes, and folate in beans, spinach and broccoli). Cellulase is produced primarily by fungi, bacteria and protozoans.5
  • Maltase: Digests complex and simple sugars, as well as unused glycogen in muscle tissue. Glycogen is converted from sugars and starches and is stored in muscle cells for future use.6
  • Invertase: Breaks down sucrose products like refined sugar, a common food source that can contribute to digestive stress.7
  • Alpha galactosidase: Helps digest carbohydrates found in certain foods, such as beans, that are not readily digestible in the small intestine. Undigested carbohydrates then pass into the large intestine where they are fermented by bacteria and produce gas, bloating, pain and general discomfort.

Choosing supplements

Here are two important points to keep in mind when choosing a food enzyme supplement:

  1. Animal-source enzymes, often called pancreatic enzymes, usually target digestion of protein.
  2. Plant-source enzymes are either derived from actual plants, or cultivated on a plant medium. They are more acid stable than animal-sourced enzymes so are active across the entire pH range in the digestive system, and can digest the full range of food groups. The highest quality digestive enzyme supplements are made by simply inserting the enzyme-rich growing medium into capsules. This means there is no extraction involved, no chemicals, and no drying process to damage the integrity of the enzymes or contaminate the final product. The amount, activity and type of enzymes in the final product depend on the medium used and the length of time the organism is allowed to grow under controlled conditions.

There is an ongoing controversy about whether cultivated or pancreatic enzymes are more suitable for our canine and feline companion animals, but both can be used successfully.

Diseases resulting from enzymatic dysfunction

Diseases that disrupt the synthesis or secretion of digestive pancreatic enzymes cause mal-digestion with subsequent malabsorption.

  • Exocrine pancreatic insufficiency (EPI) occurs when there is a loss of 85% to 90% of exocrine pancreatic mass. Without the pancreatic enzymes, severe mal-digestion and malabsorption of starch, protein and most notably fat will occur. EPI in dogs is often complicated by secondary bowel pathogen overgrowth and antibiotic-responsive diarrhea, which further disrupts nutrient digestion and absorption. EPI is relatively uncommon in cats and is most frequently due to chronic pancreatitis.
  • Lactase deficiency from a brush border enzyme deficiency may cause milk intolerance in adult dogs and cats.
  • Amylase deficiency from acquired brush border defects may be seen in the course of generalized small intestinal disease. Carnivores are not suited to high carbohydrate diets, as they cannot maintain long term production of the quantity of amylase enzymes necessary to properly digest and utilize them. Proteins in grains are also less easily digested than animal proteins. Allergies and other chronic immune problems may develop, as noted in the subsequent section on CIC issues.8
  • Allergies and food sensitivities are common. Allergens are almost always proteinaceous, and undigested particles of food may cross the intestinal barrier into the bloodstream, where they are identified as foreign substances by the immune system. This wastes precious defense resources on a “false alarm” rather than defending the body from true hazards, and is referred to as food leucocytosis (a food-driven increase in white blood cells). CICs (circulating immune complexes) start out as undigested large protein molecules (primarily from wheat, corn, dairy and soy) that can be absorbed into the bloodstream. Antibodies couple with these foreign protein invaders to form CICs. At first, these CICs may be neutralized by the immune system, then eliminated through the lymphatic system and kidneys. A glut of CICs can overwhelm the body’s ability to eliminate them, so the body is forced to “store” them in its own soft tissues, resulting in an ongoing allergic immune response that leads to inflammation9 and, ultimately, autoimmune disorders.10 In fact, studies have shown that diseases that present high CIC levels can be improved or even cured by eliminating the excess CICs.11 Furthermore, putrefaction in the gut caused by undigested food may jeopardize the integrity of the intestinal wall, allowing various environmental toxins in the food to find their way into the blood and body.

There is strong evidence that glyphosate can poison the microbiomes leading to a host of other health problems, including systemic illness, digestive issues, malnourishment and fatigue, which all symptoms considered triggered by gluten sensitivity or intolerance. Some research shows that glyphosate inhibits a type of digestive enzyme that helps process and activate vitamins A and D3, along with detoxifying pollutants.12 Based on this research, some scientists have concluded that it’s not the gluten in wheat that’s the problem. It’s the glyphosate, or even both.

Image courtesy of Carola Schleuss, CNC, CMP.

Practical oral supplementation 

There are many digestive enzyme products on the market, often combined with probiotics.

When enzymes are fed with meals, they aid in digestion. When you feed the exact same enzymes at other times, they work systemically for metabolic purposes. If the intent is pre-digestion, non-enteric coated products are best. Their presence in the upper stomach normalizes the signaling mechanisms that govern the release of stomach acid or the production of bicarbonate and enzymes by the pancreas. Given between meals, non-animal-derived enzymes, such as microbial or fungal enzymes, can be used as anti-inflammatories.13

Research has now shown that proteolytic enzymes can increase the permeability of the mucosal epithelium and facilitate bioavailability by a mechanism of self-enhanced paracellular diffusion.14 They are best given between meals for allergies, as they help to remove or digest circulating proteins that can cause reactivity.

As an added bonus effect, proteolytic enzymes have the ability to digest and destroy the protein-based defense shield of every pathogen, allergen and rogue cell, thereby leading to their ultimate elimination. Enteric pathogens often gain access to the body by altering the structure and function of tight junctions to increase permeability of the barrier via the secretion of proteases, which can cleave tight junction proteins, or by altering the cytoskeleton.15

Specific uses in clinical practice

Though animals being fed a raw meat diet (frozen or home-prepared) rarely need digestive enzyme supplements, they may be needed during diet transitions, or when part of the diet is plant-based; in the wild, most plant materials would be “pre-digested” in the ingesta of the intestinal tract. Any animal whose diet is predominately processed will greatly benefit from digestive enzymes, as processed foods are enzymatically dead.

Animals with digestive upsets (gas, diarrhea, vomiting), yeast overgrowth and sluggish metabolism clearly benefit while deeper cures are attained. Many animals undergoing stress (travel, anxiety, fear of things like thunder or fireworks) benefit, as do aged animals, since their enzyme systems are probably depleted. Antibiotics or other medications may interfere with the microbiome and enzyme function, so both digestive enzymes and probiotics are routinely indicated.


Recently, research scientists have found evidence that impaired digestion, as well as decreased enzyme activity in the blood, are directly related to the aging process and many of the illnesses and chronic degenerative conditions so prevalent in modern society. These studies suggest that as we and our animals age, the number of enzymes and their activity levels decrease in our bodies.

As Dr. Howell said in his book on enzyme nutrition, “A person’s life span is directly related to the exhaustion of their enzyme potential. And the use of food enzymes decreases that rate of exhaustion, and thus, results in a longer, healthier and more vital life.”16 We can certainly enhance the life of our dog and cat patients by considering the contribution of enzymes to their wellness.




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4Kelly JJ and Alpers DH. “Properties of human intestinal glucoamylase”. Biochim. Biophys. Acta 315: 113–122. 1973. ncbi.nlm.nih.gov/pubmed/4743896

5Parada J, Aguilera JM. “Food microstructure affects the bioavailability of several nutrients.” J Food Sci 2007, 72:R21-32. ncbi.nlm.nih.gov/pubmed/17995848

6Weinik M, Campagnolo D. “Acid Maltase Deficiency Myopathy.” Medscape 25 Mar 2014. (Accessed 21 Jul 2014.) emedicine.medscape.com/article/313724-overview

7Lieberman, P. “Is allergy or intolerance to sweet or sugar exist, and how to manage or treat it?” AAAA. (Accessed 21 Jul 2014.) aaaai.org/ask-the-expert/allergy-intolerance-sugar.aspx

8Malabsorption Syndromes in Small Animals, merckvetmanual.com/digestive-system/diseases-of-the-stomach-and-intestines-in-small-animals/malabsorption-syndromes-in-small-animals

9Arazi A, Neumann AU. “Modeling immune complex-mediated autoimmune inflammation.” J Theor Biol. 2010 Dec 7;267(3):426-36. ncbi.nlm.nih.gov/pubmed/20832412

10Cano PO, Jerry LM, et.al. “Circulating immune complexes in systemic lupus erythematosus.”Clin Exp Immunol. Aug 1977; 29(2): 197–204. ncbi.nlm.nih.gov/pmc/articles/PMC1541106/pdf/clinexpimmunol00234-0013.pdf

11Stauder G, Ransberger K, Streichhan P, Van Schaik W, Pollinger W. “The use of hydrolytic enzymes as adjuvant therapy in AIDS/ARC/LAS patients.” Biomed Pharmacother. 1988;42(1):31-4. ncbi.nlm.nih.gov/pubmed/3408806

12Samsel A, and Seneff S. “Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance.” (2013 December) NCBIInterdiscip Toxicol. 2013 Dec; 6(4): 159–184. Retrieved from ncbi.nlm.nih.gov/pmc/articles/PMC3945755/

13Rachman B. “Unique Features and Application of Non-Animal Derived Enzymes.” Clinical Nutrition Insights. 510 8/97 Vol. 5, No. 10. (Accessed 24 Jun 2014.) cudoc.com/Digestive%20Enzymes.PDF

14Kolac C, Streichhan P, Lehr C-M. “Oral bioavailability of proteolytic enzymes.” European journal of pharmaceutics and biopharmaceutics. 1996, vol. 42, no4, pp. 222-232 (68 ref.) cat.inist.fr/?aModele=afficheN&cpsidt=3191444

15Berkes J, Viswanathan VK, Savkovic SD, Hecht G. “Intestinal epithelial responses to enteric pathogens: effects on the tight junction barrier, ion transport, and inflammation”. Gut 2003, 52:439–451.

16Howell E. Enzyme Nutrition: The Food Enzyme Concept  New Jersey: Avery Publishing Group, 1985.

*This article has been peer reviewed.


Dr. PJ Broadfoot graduated Cum Laude from Kansas State University School of Veterinary Medicine in 1981, and started her own practice in Van Buren, Arkansas in 1982. She developed an early interest in the nutritional aspects of healing, which progressed over the past 18 years into a holistically oriented practice. Dr. Broadfoot was hired in 2001 as a veterinary consultant for Heel, and has presented lectures on homotoxicology. She has also lectured internationally for the Vetri-Science Company, a recognized authority in the research and product development of high quality supplements for animals. Dr. Broadfoot is a member of the CIVT faculty, as well as the AVMA, the Arkansas VMA, and the AHVMA.