OBJECTIVES: To evaluate the effect of a probiotic product in acute self-limiting gastroenteritis in dogs.METHODS: Thirty-six dogs suffering from acute diarrhoea or acute diarrhoea and vomiting were included in the study. The trial was performed as a randomised, double blind and single centre study with stratifi ed parallel group design. The animals were allocated to equal looking probiotic or placebo treatment by block randomisation with a fi xed block size of six. The probiotic cocktail consisted of thermo-stabilised Lactobacillus acidophilus and live strains of Pediococcus acidilactici, Bacillus subtilis, Bacillus licheniformis and Lactobacillus farciminis.RESULTS: The time from initiation of treatment to the last abnormal stools was found to be signifi cantly shorter (P = 0·04) in the probiotic group compared to placebo group, the mean time was 1·3 days and 2·2 days, respectively. The two groups were found nearly equal with regard to time from start of treatment to the last vomiting episode.CLINICAL SIGNIFICANCE: The probiotic tested may reduce the convalescence time in acute self-limiting diarrhoea in dogs.