This study evaluated the effect of supplementation with canine-derived probiotic Bifidobacterium animalis strain AHC7 (lams Prostora, Procter & Gamble Pet Care) on the resolution rate of acute idiopathic diarrhea in dogs randomly assigned to receive a placebo (n=18) or the probiotic (n=13). Nutritional management with the probiotic fed at 2 x 10(10) CFU/day significantly reduced the time to resolution (3.9 +/- 2.3 versus 6.6 +/- 2.7 days; P < .01) and reduced the percentage of dogs that were administered metronidazole (38.5% versus 50.0%) compared with placebo. Probiotic B. animalis AHC7 may provide veterinarians another tool for management of acute diarrhea in dogs.