I used Transfer Factor on my dog, though I swapped to Green & White Tea Extract, Aloe Vera Extract & Immpower. That seems to be working better than Transfer Factor. But that's just my personal experience with it - I would not rely on any of these as standalone treatments. They are not strong enough, however they will kick up your immune system!
I just started my dog on Cesium Chloride external application. We have to wait and see whether it works.