Short-chain fatty acids (SCFA) are produced by bacterial fermentation of dietary fiber. SCFA concentrations are dependent upon the type of fiber. The types of SCFA typically found in the feline gut are acetate, propionate, and butyrate. In this study, colonic tissue was obtained from healthy cats and kittens, and contractions were monitored and compared with the maximal contractions obtained with acetylcholine. Longitudinal and circular contractions were measured. Results concluded that SCFAs induced contraction of longitudinal, but not circular, smooth muscle from the proximal and distal portions of the feline colon. This response was seen also in the kittens but at a smaller amplitude. SCFAs have several physiologic effects on the colon, including promotion of colonocyte differentiation and proliferation, stimulation of sodium and water reabsorption, enhancement of colonic blood flow, inhibition of pathogenic bacterial growth, and production of metabolic energy. Stimulation of colonic smooth muscle contraction may be helpful in disorders of colonic motility, such as megacolon. Dietary fiber has been recommended because of its natural laxative effects by increasing fecal water content and increasing frequency of defecation. The role of SCFA on colonic smooth muscle contraction may also play an important role in colonic motility disorders.

COMMENTARY: The term "dietary fiber" encompasses a spectrum of plant-based substances that can interact with the gastrointestinal tract in a variety of ways. The major difference among these is whether they are digestible (read fermentable) or nondigestible.  We have long known that fiber has beneficial effects on colonic function. One of the most important effects is attributable to its bulk, which stretches colonic muscle to enhance contractility. Fermentable fibers are degraded by the colonic microflora to produce short-chain fatty acids (SCFAs), which have additional beneficial effects. SCFAs are the major energy source for the colonocyte, and as demonstrated in this study, may play an important role in stimulating colonic contractile activity. Their use as adjunctive therapy in gastrointestinal disease has great potential.

Short chain fatty acids stimulate feline colonic smooth muscle contraction. Rondeau MP, Meltzer K, Michel K, McManus CM, Washabau RJ. J FELINE MED SURG 5:167-173, 2003.