Before the grand old age of one year old, one of my bitches has had a heavy worm burden, giardia and campylobacter (tested and diagnosed).  In the last few months (she's 17 months) she has had a few bouts of diarrhoa, the last one was extremely fluid and resulted in a trip to the vet.  He didn't feel it was connected with the campylobacter, and couldn't come up for a reason for it, other than dogs get diarrhoa, the weather, etc, etc, basically he wasn't in the least bit concerned.  She's now absolutely fine again, but I think that given her history the chances are her gut isn't perhaps quite as healthy as it should be.  She, I should add, is, and always has been, the perfect image of fitness and health - fabulous silky, shiny coat, masses of energy, etc.
I give her goats yoghurt when she's had a bout of diarrhoa, and am now giving her cows probiotic yoghurt.  Has anyone else any experience of a similar digestive history and if so, what would you suggest?
I read on another thread here about probiotics that come in a paste/tablet form, but is this any better than giving live yoghurt? It's certainly more expensive.
She also has banana when she's on the yoghurt regime - I understand that banana is a very good 'food' source for the good bacteria in the gut.
I'm not too concerned by her diarrhoa bouts, as she is otherwise so fit, and a couple I could possibly link to a particular type of chewy, but I would like to improve her gut without the use of chemicals.
Thanks for any suggestions

My bitch in her younger days used to be prone to bouts of diarrhoea, following a severe reaction to an overdose of wormer as a young pup.  Eventually, my vet diagnosed an overgrowth of bacteria in the gut, for which she was treated fairly successfully.  In her middle years, she suffered a bout of constant vomiting.  I then opted for an endoscope test, which showed a very small amount of helicobacter pylori in the stomach.  If left untreated, it could have led to an ulcer or a tumour.  She was given strong antibiotic, and the bouts of upset stomach have never returned - it's been a few years now.
I don't think the helicobacter could have been there the whole time, but obviously her gut flora were never as they should have been.  I used a powdered probiotic, and that helped - it was recommnded to me by someone who had used probiotic for horses.  I can't remember the brand, but I think it was TDP.  Yes, I just looked it up - it was TDP Probiotic by Aviform.  I should think the natural yoghurt will do just as well, though.

Hi, thanks for that.  This is what I am hoping to avoid by ensuring the gut flora is right now, I shall go and have a look at TDP now.