Cost-effective

My two-year-old Leonberger dog has suffered from bouts of diarrhoea since I brought him home at eight weeks of age. Many of these 'bouts' have been quite serious and the treatment has proved to be expensive due partly to his size. It is also very unpleasant to deal with this problem on a regular basis.
Tests showed that Tallis suffers from an overgrowth of bacteria in the gut and it was suggested eventually that he should take Synbiotic D.C. (Probiotic & Prebiotic powder) administered as one tablet per day.
This I'm glad to say is extremely effective and, as this is a non-prescription medication, the cost is approximately 50p per day per tablet.
However, glancing through 'Healthspan Directory' I noticed that the 'human' equivalent Probiotic costs approximately 13p per tablet, which leads me to wonder is there in fact any difference in these apart from the cost?
I should be very grateful is anybody could inform me as even over one month the saving would be considerable.
Mrs B Newton, Hertford