Iams Nutrition Insider: Comparing prebiotics and antibiotics in treating SIBO in dogs (Sponsored by Iams)

Fecal consistency and volume in dogs with suspected small intestinal bacterial overgrowth receiving broad spectrum antibiotic therapy or dietary fructooligosaccharide supplementation.
Jul 01, 2010

An abstract presented at the American College of Veterinary Internal Medicine Congress

The medical management of dogs with suspected small intestinal bacterial overgrowth, or SIBO, usually involves antibiotic therapy. Repeated cycles of antibiotic therapy are often necessary. Effective dietary therapy may also be useful in managing these cases.

The aim of this study was to compare the effects of broad-spectrum antibiotic therapy and a fructooligosaccharide supplemented diet (FOS diet) on fecal consistency and volume in dogs with suspected small intestinal bacterial overgrowth.

The trial

Client-owned pet dogs (n=30) were recruited from accessions to the Gl Laboratory. Criteria for entry into the trial included clinical signs and a history consistent with small intestinal bacterial overgrowth; an abnormally high serum folate concentration (> 14 μg/L), typically with an abnormally low serum cobalamin concentration (< 290 ng/L); and a normal serum TLI concentration.

Dogs were randomly selected to receive either antibiotic therapy (tylosin, 15 mg/kg orally b.i.d..; n=15) for 30 days or a diet containing 1% FOS (Eukanuba Low-Residue Adult Canine, Dry; n=15) for 60 days.

Owners kept daily records of their dogs' appetite, fecal volume and consistency, and the number of bowel movements passed. Appetite was scored from 0 (very poor) through 2 (normal) to 4 (excessive). Fecal volume was scored from 0 (normal) to 2 (copious), and fecal consistency was scored from 1 (liquid) through 4 (normal) to 7 (extremely hard). Data were analyzed by two-way ANOVA.


Mean appetite scores were significantly higher in the diet group throughout the study period (P < 0.01). Fecal volume scores normalized significantly in both treatment groups (P < 0.01); however, the effect of the two treatments differed significantly over time (P < 0.01). Rapid normalization of fecal volume in the antibiotic group was followed by deterioration on withdrawal of antibiotics. Fecal volume in the diet group reduced gradually, remaining significantly lower at the end of the trial.

Fecal consistency improved significantly with both treatments (P < 0.01), but the effects of the two treatments differed significantly over time. Tylosin-treated dogs showed immediate normalization of fecal consistency with deterioration on withdrawal of therapy. The FOS-diet group exhibited a slow normalization of fecal consistency, which was maintained until the end of the trial.

The number of daily bowel movements showed no significant change over time with either therapy.


We conclude that both broad-spectrum antibiotic therapy and FOS-supplemented diets are associated with improved fecal character in dogs with suspected small intestinal bacterial overgrowth. The beneficial effects of antibiotic therapy have rapid onset but may be transient, while the benefits from the FOS diet are slower in onset but are sustained while the diet is administered.

CG Ruaux, 1 MATetrick, 2 JM Steiner, 1 and DA Williams 1

1Gastrointestinal Laboratory, Texas A&M University, College Station, Texas
2P&G Pet Care, Lewisburg, Ohio