Once I had similar problem, I couldn't stop diarrhea with usual diet food (chicken etc.) and I gave to my bitch Hill's i/d (http://www.hillspet.com/products/pd-canine-id-canine-gastrointestinal-health-canned.html). After few days, she was OK and she started to eat normal food, without any problems.
That is precisely what my vet has just given my basenji for his bland diet.
Hope it works!
There are so many bacterias, and diseases cause by them, and many of them with the same apparent symptoms; since some of your basenjis have been through Giardia,how do we distinguish when it is Giardia and when it is not? How can we be aware of it at its early stages?