cause unknown.  Some 
  bespectacled old tart at a show says "Feed him 2 kgs of oats per day, it 
  sorted out my horse's hives".  And yes, 2 KGS of oats, not 2 scoops, 2 
  kilograms.  A Lot Of Oats.  Does my friend, who is otherwise 
  relatively bright, question this advice (apart from discussing with vet, who 
  in typical fashion says "well, try it and see")?  Nope, she just adds the 
  2 kgs of oats.  Needless to say, little obvious effect on 
  hives.
   
   
  Well, there's a pretty common misconception that 
  vets are also formally trained in nutrition.  They aren't---at CSU, large 
  and food animal nutrition takes up about three hours of lecture total, and 
  equine nutrition specifically took up a whole 25 minutes.  There's an 
  elective course in Feeds and Feeding (that was the one I helped teach, which 
  really drove some of my classmates nuts)<eg>, but even that just barely 
  brushes the surface and (being an elective), relatively few students took 
  it.  This is fairly typical at the other vet schools as well---even if 
  they have a formal course in nutrition, one semester doesn't even begin to do 
  more than cover the very basics.
   
  I don't mean this as a criticism of vets 
  (although I do criticize the vet schools for not including more nutrition, 
  but, hey, I'm biased)---the vet schools have four years to cram you full of 
  anatomy, diagnostics and therapeutics, and nutrition is considered 
  "preventative medicine" or "management" and there just aint enough time for 
  everything.
   
  But the point to be made is that unless your vet 
  has either done an undergrad degree in animal science of some sort, or sought 
  out a Continuing Education course, or has done ALOT of extra reading from 
  solid sources on his/her own, unless you suggest something totally 
  off-the-wall like hey, let's feed him trout chow, pipe tobacco and jet 
  fuel to kill them darn parasites, the odds are pretty good you'll get, "well, 
  try it and see".  It's just VetSpeak for "I didn't take any of the 
  elective nutrition courses but what you're suggesting will probably not kill 
  the animal outright."
   
  There are exceptions, of course---alot of vets 
  really *do* know their stuff about nutrition, and of course, Sarah is the 
  final word about equine clinical nutrition no matter who you are.  But 
  there's a world of difference between someone like Sarah that's spent years 
  doing the residency and PhD, and the "try it and see" approach.  Not a 
  bad idea to keep looking for better answers if "try it and see" doesn't do it 
  for you.
   
  (And BTW, my suggestion for the hives wouldn't 
  have been 4-5 pounds of oats---I would have taken the horse off everything 
  except grass hay, and added back in one additional feed at a time to find out 
  what was causing the hives.  If that didn't do it, I'd see about getting 
  some allergy testing done.)
   
  JMO
   
  Susan G