Fiber your pet needs, and the fancy fibers to avoid

Analysis by Dr. Karen Shaw Becker

sources of fiber for pets

Story at-a-glance -

  • Big pet food is currently evaluating miscanthus grass as an alternative fiber source in processed diets
  • Miscanthus grass may find its way into commercial pet food as yet another cheap, plentiful, high-fiber filler ingredient — an ingredient neither dogs nor cats need from a nutritional standpoint
  • In pet food, miscanthus grass is comparable to powdered cellulose (sawdust), which the pet food industry loves, but pet parents do not
  • In dog and cat diets, a small amount of species-appropriate fiber is very important, but foods loaded with fiber are very detrimental
  • Pets eating raw diets may need a source of species-appropriate fiber added to their meals

As I mention very frequently here at Mercola Healthy Pets, the pet food (feed) industry is always on the hunt for inexpensive, typically biologically inappropriate ingredients for their formulas. One of the most recent appears to be miscanthus grass, which is under evaluation as an “alternative fiber source” for use in processed pet food.

How big pet food justifies its interest in miscanthus grass

Here’s an example of the fuzzy logic the industry uses to rationalize its interest in ingredients such as miscanthus grass. From

“While not an essential nutrient for dogs or cats per se, fiber can provide benefit to their gastrointestinal health and daily elimination products.”

I guess we should be grateful for the acknowledgment that carnivorous pets don’t require added fiber of this type (as long as they’re fed a nutritionally balanced, species-appropriate diet).

“… [B]ecause fiber is by definition indigestible, it provides a mechanism to lower the caloric density of the diet. Given that over 50% of dogs and cats in the U.S. are overweight or obese, energy dilution with fiber has proven to be a valuable tool to help in weight control.”

It’s certainly true we have a pet obesity epidemic in this country, but the pet food industry fails to acknowledge its significant role in creating the problem. And doesn’t it seem there’s a better approach to keeping dogs and cats lean than adding unnecessary, biologically inappropriate filler ingredients to pet food to lower calorie counts?

“There are other values to adding fiber to the diet beyond these nutritional applications for matters that may seem more esoteric in nature, like assisting cats prone to hairballs in pushing the ingested hair toward elimination in their feces rather than vomiting them in the living space.”

First, we shouldn’t accept at face value big pet food’s premise that added fiber such as miscanthus grass has “nutritional applications,” even when it’s positioned as established fact, as it is above. As for “assisting cats prone to hairballs,” cats are strict carnivores, meaning they have even less use for cheap filler fiber in their diets than dogs do — including cats with hairballs.

That said, if you’re a cat parent, keep your eye out for new-and-improved “hairball management” formulas containing miscanthus grass, because I suspect this is where the industry may be headed with this ingredient.

So, what the heck is miscanthus grass?

“… Miscanthus giganteus … is a C4 [perennial] grass that was originally propagated for landscape cover. It has a rapid growth pattern growing to 8 feet or more and produces substantial tonnage every year. The plant grows from rhizomes and once a stand is established will persist for 20 years or more.”2

It’s landscape cover, folks. Bonus: It grows fast and tall and in huge quantities. The stems of the plant are harvested and baled, and when used for animal feed, the bales are ground into fine particles. The finished product is extremely high in fiber (90%), and most of it is insoluble fiber (83%). Beyond fiber, there are no significant nutrients in miscanthus grass.

The plant was originally farmed “to capitalize on its cellulose biomass for the ethanol industry,” according to However, the economics didn’t work out, but, “Given its similarity to cellulose, the growers thought it might be a viable candidate as a fiber source for animals.”

The cellulose mentioned just above is actually wood pulp (sawdust), primarily from pine trees. Since sawdust just doesn’t cut it with pet parents looking for more natural ingredients in their dog’s or cat’s diet, pet food companies are motivated to find alternative filler fibers to replace it (until consumers catch onto those, as well).

Like miscanthus grass, powdered cellulose has a tremendous amount of insoluble fiber, too much of which can interfere with your pet's ability to digest and assimilate the nutrients his body actually needs, like protein and minerals. High levels of cellulose can also rob cells in the colon of critical fuel, like butyrate, due to reduced fermentation. Excessive powdered cellulose in your pet's food will also cause him to produce a bigger volume of poop.

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Your healthy dog or cat needs only a small amount of species-appropriate fiber

The processed pet food industry is very invested in convincing pet parents that dogs and cats need significant amounts of fiber in their diet, despite the fact that canine and feline ancestral diets contain only minimal amounts of fiber or “roughage” (about 4% in the case of dogs) — primarily the hair, skin and teeth of prey animals, plus indigestible fibrous parts of plants and other odds and ends.

Of course, the reason pet food producers use so much fiber in their formulas is because it’s plentiful and cheap. It has little to do with offering species-appropriate nutrition to dogs and cats. When it comes to grain-free processed pet food, it’s worth asking if the newly established link between these diets and heart disease in dogs is due in part to offsetting critical amino acids in meat with an overabundance of fiber and starch.

When thinking about the need for fiber in your dog's or cat's diet, again, it's important to remember that wild canines and felines have no physiologic requirement for the plant fibers used in most processed pet food.

The fiber wild dogs and cats ingest is primarily derived from the already digested stomach contents of their prey, plus fur, tendons and ligaments, along with nibbling grasses and other plant material. Although the amount of fiber in the diet of wild dogs and cats is small (less than 5% in most cases), it serves a very important role.

Don’t get me wrong, I’m very pro-fiber, as it builds the microbiome and provides roughage for bowel health. But fiber should be provided in appropriate amounts, and not added to highly processed diets as a means of keeping stools artificially firm or tricking animals into thinking they are satiated.

Dogs and cats fed processed commercial diets very often benefit from the addition of a small amount of the right kind of fiber, which is fiber that closely mimics the gastrointestinal (GI) contents of small prey animals. However, when your pet consumes unnecessary fillers, like wads of powdered cellulose, it inhibits digestion and absorption of many vital nutrients.

The takeaway here is that a small amount of fiber is very important, but a diet loaded with fiber is very detrimental. If you're feeding your dog or cat a nutritionally balanced, species-appropriate diet, which includes low-glycemic vegetables, along with appropriate supplementation, including pet probiotics and digestive enzymes, and she's easily producing small, firm stools, she's getting the amount of fiber she needs.

If your pet needs additional dietary fiber

I’ve found that several brands of commercially available raw food diets are constipating for some pets, most likely due a lack of fiber in the food. Generally speaking, nutritionally balanced raw diets should contain low-glycemic, fibrous veggies to meet pets’ fiber needs naturally.

Vegetables also provide much needed antioxidants and phytonutrients not found in meat, bones and organs. Raw food diets without appropriate vegetables are more likely to cause constipation in your dog or cat.

In the wild, dogs and cats instinctively supplement their meat-based diets with the skin, hair and GI contents of the prey they catch. They also ingest grasses for the same reason. Since this isn’t the case with the pets living in our homes, sometimes they may need additional fiber for effective elimination, especially pets who are more sedentary.

If this is the case with your dog or cat, I recommend adding extra ground leafy veggies to their meals — about a teaspoon for every 10 pounds of body weight, given once or twice a day. If that isn’t effective, try adding psyllium husk powder at one-half teaspoon for every 10 pounds of body weight, or go with coconut or organic acacia fiber at one teaspoon for every 10 pounds of body weight, once or twice a day.

If your pet is consistently producing narrow, loose stools, he may benefit from the addition of a soluble fiber called slippery elm bark to his food. When slippery elm combines with digestive juices, it produces a gel-like material called mucilage, which coats and soothes the GI tract and helps to firm the stool. About one-half teaspoon for every 10 pounds of body weight per meal should do the trick.

Another very beneficial add-in to pet meals is canned or freshly steamed 100% pumpkin at about 1 teaspoon for every 10 pounds of body weight, one to two times a day. Pumpkin is low in calories, rich in potassium, can resolve both constipation and loose stools and also helps with regularity.

+ Sources and References