Fiber is a specific carbohydrate fraction that is not digested by the digestive enzymes of dogs and cats [1]. There are soluble fibers (forming a gel with water), fermentable fibers, and insoluble, non-fermentable fibers. The fermenting fraction is broken down by intestinal bacteria into short-chain fatty acids (SCFA), therefore the fiber provides a certain, small amount of energy (usually less than 5% of the requirement). Butyrate (butyric acid) belonging to SCFA is the basic source of energy for the colon epithelial cells [4]. In addition, it serves a mechanical and prebiotic function in the body. It acts as an intestinal cleansing brush, gives the feces appropriate volume and lubrication, and is also a source of energy for the good bacterial flora (microbiome) of the intestines [2]. Although in nature wild cats consume it in minimal amounts (mainly from hair, feathers and chitinous shells of insects), in domestic dogs, a properly selected fiber supplement perfectly regulates the functioning of the digestive tract.
What it contains: Vegetables, fruits and psyllium husks.
Deficiency: Leads to slower intestinal peristalsis. The stool becomes very dry, clumpy, hard and difficult to pass, resulting in painful constipation. Moreover, too small a volume of feces means that the animal is unable to naturally empty the perianal glands during defecation, which is the main cause of their clogging (often recurrent) and inflammation. In the form of inulin, fructooligosaccharides (FOS) and mannanoligosaccharides (MOS), it is recommended as a prebiotic for constipation, chronic and acute diarrhea or hairless hairs in the digestive tract.
Excess: Fiber acts like a sponge in the intestines. If there is too much of it, it drastically speeds up intestinal transit and binds too much water. This results in bloating, gas and loose, large-volume bowel movements (so-called cow cakes). The most dangerous phenomenon, however, is the phenomenon of blocking absorption: excess dietary fiber acts as a glue that binds key nutrients - including: taurine and minerals such as zinc, iron and calcium - so they are not absorbed and are excreted from the body [2][3]. Vitamins and minerals are then removed from the body too quickly (diarrhea), most of them do not even have time to be absorbed.
Sources
- National Research Council (NRC) (2006). Nutrient Requirements of Dogs and Cats - no established minimum requirement for fiber. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ (2010). Small Animal Clinical Nutrition, 5th Edition - types of fiber, fermentation to SCFA and effects on mineral absorption. https://www.markmorrisinstitute.org/sacn5.html
- McCauley SR, Clark SD, Quest BW, Streeter RM, Oxford EM (2020). Review of canine dilated cardiomyopathy in the wake of diet-associated concerns — high fiber content and taurine balance in dogs. J Anim Sci 98(6):skaa155. https://doi.org/10.1093/jas/skaa155
- Dietary Fiber: Optimizing Gastrointestinal Health (proceedings). dvm360 - fiber fermentation to SCFA and their energy contribution; butyrate as fuel for colonocytes. https://www.dvm360.com/view/dietary-fiber-optimizing-gastrointestinal-health-proceedings