The thousands of enzymes produced by the body aid in a wide variety of chemical reactions. There are two major classes of enzymes: metabolic and digestive. Digestive enzymes are produced primarily in the pancreas and released into the duodenum to help digest food coming from the stomach. The intestines themselves also secrete amylase and other digestive enzymes.

Their function in digestion

Three main types of enzyme help break down macronutrients in food:

1. Protease, to break down protein
2. Lipase, to digest fat.
3. Amylase, to process carbohydrates.

Most mammals produce amylase in the saliva, but dogs and cats do not. This reflects their expected diet of meat and organs from prey. Herbivores and omnivores have flat molars that crush and chew food, but the carnivore’s dentition is perfectly designed to capture and kill prey, and to rip and tear meat from bone. Carnivores don’t spend much time chewing; nor do they consume many carbohydrates, so there is no need for amylase in the mouth.

In addition, all cells carry within them the means for their own destruction in the form of lysozymes. These packets of enzymes break open upon cell death, and help break down (digest) the contents of the cell, either for recycling (in a living body) or decomposition. Because the natural prey diet of canines and felines is consumed raw, these lysozymes may also contribute to efficient digestion of food.

The argument could be made that a carnivore’s GI transit time is too fast for lysozymes to have a meaningful impact on digestion. However, when a carnivore kills a large prey animal, that carcass is likely to sit for a while (it takes about two weeks for a mountain lion to consume a whole deer). Wild canids commonly take advantage of the lysozomal process by burying parts of the carcass, and digging them up and eating them weeks later. In those scenarios, both internal lysozymes and various external organisms (bacteria, fungi) contribute to the food breakdown normally performed by the pancreas.

The case for routine supplementation

When heat destroys (“denatures”) the natural shape of enzymes, they become nonfunctional. In dogs and cats that eat heat-processed pet food, those enzymes are absent; the pancreas must provide all the enzymes needed to digest the food.

In addition, commercial dry kibble is also much higher in carbohydrates than the carnivore’s natural prey diet. While cats’ and dogs’ pancreatic and intestinal tissues can and do produce amylases that are fully capable of digesting carbohydrates, the lack of salivary amylase reminds us that nature did not intend carbs to be their primary source of nutrition.

“Evidence…strongly suggests that eating foods devoid of enzymes as a result of cooking, food irradiation, and microwaving causes an enlargement of the pancreas and also stresses associated endocrine glands….” writes Gabriel Cousens, MD, in his book Conscious Eating. “In all of nature, the human pancreas is three times larger, as compared to total body weight, than that of any other animal. What is interesting is that when mice are fed cooked foods, the ratio of their pancreas weight to total body weight becomes approximately that of a human’s. When they are switched back to a raw-food diet, their pancreas shrinks back to normal size. The most obvious conclusion is that the pancreas becomes hypertrophied, or enlarged, because it is forced to keep up a high digestive enzyme output.”

Research in animals has shown that the production of digestive enzymes is independent of diet. That is, animals are biologically programmed to produce specific types and amounts of digestive enzymes in response to food ingestion, regardless of what food they actually eat. Only major evolutionary shifts, such as changing from omnivorous to insectivorous lifestyles, affect these systems. Our carnivorous pets have not, and cannot, adapt their digestive functions to processed diets, which, after all, have only been widely used for a few decades.

Moreover, recent research shows that in humans with gastrointestinal disease, but more importantly, even in normal individuals, supplementation with digestive enzymes substantially increased digestion in the lumen of the small intestine, and improved the bioavailability of proteins and carbohydrates. Especially in view of the highly processed diet that most of our pets are eating, this implies that most healthy adult dogs and cats can benefit from a digestive enzyme supplement.

Digestive enzymes help pets digest and assimilate food better–any food. This does several things your clients will appreciate: 1. Saves them money — because their pets will be getting more nutrition from the same food, they may be able to feed less, and therefore stretch their budgets a little more. 2. Reduces the amount of stool because less food is wasted through improper digestion. 3. Improves the quality of the stool. 4. Makes their pets feel more satiated, which can reduce begging. 5. Makes their pets healthier because they are getting more of the nutrition they need.

Digestive enzymes for pets typically come in capsules or powdered form, making it easy to sprinkle on or mix with wet food. For most pets, the best enzymes come from plants or fungi (yeast), because they can survive the trip through the stomach’s acidic environment. Make sure the enzymes you choose contain at least protease, lipase and amylase (many also contain cellulase, which is useful if the food contains fibrous vegetables or grains).

Digestive enzymes are certainly useful for dogs and cats with any type of digestive or pancreatic issues. But don’t forget that clinically normal patients can greatly benefit from them as well.

While experimentation has shown that pancreatic extracts work best for EPI, plant- or fungal-source enzymes may be a better choice for other digestive issues. They tend to resist digestion better than pancreatic extracts, and function in a wider range of pH.

Clinical uses of digestive enzymes

In veterinary medicine, there are several medical conditions in which digestive enzymes may be deficient or absent. Exocrine pancreatic insufficiency (EPI), pancreatic hypoplasia, and pancreatitis all affect the production of digestive enzymes, and potentially other products of the pancreas as well, such as insulin and glucagon. Inflammatory bowel disease (particularly lymphocytic-plasmacytic gastroenteritis) may impact the production and/or release of digestive enzymes. It is worth remembering that in cats, pancreatitis is often overlooked and likely vastly underdiagnosed. Additionally, cats have a more limited enzyme capability in their digestive tracts that does not favor starch digestion and absorption; this may make them more susceptible to developing diabetes mellitus when free-fed the standard high-starch kibble diet.

We are just starting to realize that digestive enzymes may be useful in situations besides overt maldigestion. There is also evidence that diabetic animals may benefit from digestive enzymes.

In EPI, enzyme replacement consists of dried porcine pancreatic extracts. However, much of the effectiveness of such extracts is lost due to partial digestion of the enzymes in the stomach. While experimentation has shown that pancreatic extracts work best for EPI, plant- or fungal-source enzymes may be a better choice for other digestive issues. They tend to resist digestion better than pancreatic extracts, and function in a wider range of pH.

An unusual clinical use for protease

The proteolytic enzyme bromelain, from pineapple, is used to reduce inflammation from infection and injuries. The University of Maryland suggests that bromelain can be used to decrease swelling, bruising, healing time and pain after surgery and physical injuries, such as tendinitis, sprains and strains, and other minor muscle injuries. In Europe, bromelain is used to treat sinus and nasal swelling following ear, nose and throat surgery or trauma. The dose for this special use is 50 mg to 100 mg per ten pounds of body weight, divided into two doses; mix with cool water and administer orally for up to ten days.


References

Cousens G. Conscious Eating. Germany: Georg Thieme Verlag. 2001.

de-Oliveira LD, Carciofi AC, Oliveira MCC, et al. “Effects of six carbohydrate sources on diet digestibility and postprandial glucose and insulin responses in cats.” J Anim Sci. 2008, 86:2237-2246. Available online at: http://jas.fass.org/content/86/9/2237.

Howell E. Enzyme Nutrition: the food enzyme concept. New Jersey: Avery Publishing Group. 1985.

Kienzle E. 1993. “Carbohydrate metabolism of the cat. 1. Activity of amylase in the gastrointestinal tract of the cat.” J. Anim. Physiol. Anim. Nutr. (Berl.) 69:92–101.

Medhekar R. “The First Quantitative Evidence Proving The Efficacy Of Supplemental Enzymes.” 2004. http://www.enzymeessentials.com/TNO_Research_Web.pdf. Accessed 3/2/12.

Ramírez-Otárola N, Sabat P. “Are levels of digestive enzyme activity related to the natural diet in passerine birds?” Biol Res. 2011;44(1):81-8.

Scherk M. “Feline Pancreatitis: Underdiagnosed and Frequently Overlooked.” International Veterinary Emergency and Critical Care Symposium. 2010.

Schondube JE, Herrera-M LG, Martínez del Rio C. “Diet and the evolution of digestion and renal function in phyllostomid bats.” Zoology (Jena). 2001;104(1):59-73.

University of Maryland Medical Center, Medical Reference Library. http://www.umm.edu/altmed/articles/bromelain-000289.htm. Accessed 3/6/12.

Williams DA. “Exocrine Pancreatic Insufficiency.” British Small Animal Veterinary Congress. 2009.

Jean Hofve, DVM, earned her Doctor of Veterinary Medicine at Colorado State University. In addition to conventional veterinary training, she studied veterinary homeopathy, homotoxicology, Reiki, and other holistic modalities. She has researched pet food and feline nutrition for nearly two decades, and is an expert on holistic pet health and the commercial pet food industry. She is an official advisor to AAFCO, the organization that sets pet food rules and standards in the U.S. and Canada. Dr. Hofve co-authored the book Holistic Cat Care.