This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.


Dietary fibre is a term used to describe a group of compounds which are found in foodstuffs. It was previously defined as :

"any substance of plant origin which is undigested by human alimentary tract enzymes" .

This group of compounds are mainly complex carbohydrates. Generally, they are also not digested by enzymes secreted by other single-stomached animals such as the cat and dog. However, it is inaccurate to regard dietary fibres as being inert because they have various effects on the body, and although not digested in the small intestine, they are metabolised by bacteria in the large intestine. The resulting substances of this process (mainly short-chained fatty acids such as acetic, propionic and butyric acids) acidify the colonic contents resulting in water retention and fecal bulking.

In ruminants (cattle, sheep, goats) dietary fibre is fermented by ciliates, protozoa, yeasts and fungi activity as well as bacteria in the rumen making them available for absorption in the small intestine.

(In 1988 the British Nutrition Foundation appointed a Task Force to review the subject of dietary fibre and concluded that the term "complex carbohydrate" was better than "dietary fibre" as it embraced other compounds (known as polysaccharides - which consist of more than 20 monosaccharide units). This definition includes some polysaccharides of animal origin which have similar biological effects to those of plant origin , and so it may be a preferable definition to use.)


The health benefits of fibre have been known for many years :

"Eat unbolted bread for it's salutory effects on the bowels " Hippocrates 450 BC

"To the human body it makes a great difference whether the bread be made of fine flour or coarse, whether of the wheat with the bran or the wheat without the bran" Hippocrates 450 BC

In fact, dietary fibre has many positive and negative effects on the body including physiological, structural, metabolic and functional effects.

Rations high in dietary fibre produce the following effects :

On the intestine itself

      1. Increased small intestine wall thickness (mucosa)
      2. Increased small intestine weight
      3. Changes in the villi :
      4. Increased number of neutrophils

        Increase mitosis (cell division rate)

        Increased number of crypt cells

        Blunting and disarray of villi (soluble fibre)

      5. Thinning of colon wall

On intestinal contents

    1. Alter the transit time ( of food through the intestinal tract. Generally fibre increases segmental contractions. This slows gastric emptying, slows transit through the colon, but can have a varying effect on small intestine transit time.
    2. Increased secretion of enzymes
    3. Altered pH of intestinal contents (chyme)
    4. Increased viscosity of chyme
    5. Reduced digestion (link to gloss/digestion) of nutrients
    6. Reduced absorption (link to gloss/absorption) of nutrients
    7. Slows the absorption rate of nutrients e.g. glucose
    8. Increased colonic fermentation

On fecal production

  1. More fecal waste material
  2. Fecal bulking due to retention of water
  3. The fecal stool is softer and easier to pass
  4. More gas production (due to increased fermentation)
  • Flatulence
  • abdominal discomfort (sometimes)
  1. Increased fecal nitrogen and fat excretion
  2. Changes bacterial content of large intestine
  3. Metabolic effects

    1. Altered glucose tolerance (absorption)
    2. Reduced post-prandial insulin secretion
    3. Reduced triglyceride and fatty acid synthesis
    4. Reduced plasma and liver fat concentrations

All fibres are not the same. Basically there are two forms of dietary fibre - soluble (e.g. pectin, guar gum) and insoluble (e.g. cellulose). These are readily available as supplements, as constituents in raw ingredients and incorporated in "special diets" developed to be used in the management of animals with known disease profiles.

Different types of fibre can have significantly different effects e.g. cellulose has relatively little effect on mineral absorption compared to lignin which has a much greater effect.

Low fibre content rations have been linked to the occurrence of colonic carcinoma in humans living in Western Society No such association has been proved to exist in domesticated animals. Some fibre is advocated to be included in pet foods formulated for cats and dogs, but there is little scientific evidence to prove that fibre is actually necessary for normal gastrointestinal function.

However, the effects of fibre are being used in cats and dogs the management of a variety of clinical conditions including :

    1. Diabetes mellitus - delayed glucose absorption
    2. Constipation - fecal bulking, softening of the stool and transit time
    3. Obesity - bulking effect to induce satiety, reduced nutrient absorption, dilution of calorie content
    4. Hyperlipidemia - bulking effect to induce satiety, reduced fat absorption
    5. Colitis - fecal effects and transit time
    6. Lymphangiectasia - effects on fat availability, and on chyme


Last updated : October 2013