I can at least address why we recommend it SOMETIMES.  We DO NOT
recommend their regular foods as the best food out there-for felines
(we don't see dogs) we recommend Wellness, as we feel it's the best cat
food on the market right now.  But Hill's has a large line of diets
specifically forumated for certain medical problems (they have a diet
for animals w/kidney problems, crystals in their urine, etc), so THAT is
why we keep it in stock and recommend it at times.
 
For other animals, we do our own research and recommend the foods we
feel are best suited to their individual and species/breed needs (like
Harrison's Bird Diet pellets for pet birds, Oxbow's Cavy Cuisine for
guinea pigs, etc.).  While we're not thrilled with the Hill's for their
regular diets, their problem-specific diets are often the easiest and
best ways to address the nutritional needs of certain medical problems.
 
Hope this sheds some light!
 
-April  (incidentally, A/D, which is often used to help bulk up and get
 nutrients into sick ferrets is a Hill's product)
[Posted in FML issue 3946]