Jon, and FML, I hope this information will help you when chosing a pet food. I am obtaining info on Science Diet's C/D just to make sure I am familiar with the product, but here are the *general* guidelines that Iams' and outside research has found to be true. Acidic urine is natural by-product of eating a meat-based diet. There are other factors, such as vegetable products that may influence acidity Other things you can look for in a food when dealing with an animal exhibiting "crystals" or solids in urine: (there are different types and causes of "crystals" or solids in urine which is why I have used quotation marks). 1) Magnesium is the #1 factor/constituent of solids that "crystalize" or precipitate in urine - magnesium should be shown on the bag to be less than 0.01%. If it is not listed, call the manufacturer. 2) "Crystal" formation is inhibited in a urine that is slightly acidic (6.6 - 6.8 pH is the target for feline research) 3) Studies have conclusively shown that ASH is *NOT* the factor you should be looking for when choosing your pets food. It is difficult after the raving publicity in the 70's and 80's to try and re-educate the public and some vets with these new findings (remember, some human doctors are behind on current research findings too so I am not slamming vets here). If you would like information on the studies, please call the Iams 1-800 # you can find on every can and bag of food.(1-800-525-4267) REMEMBER: Ash content also varies from soft/moist food, to semi-moist, and dry foods. Ash is really only a measurement of the final remaining dry matter when a food is incinerated - which is all the vitamins and minerals our critters need. (Of course if the ash content is WAAAAY to high, it is possible that there are undesireable ingredients in that food.) 4) If the bag or ingredients say ADDED TAURINE, you can bet that the real meat content of the food is lacking. Taurine is naturally occurring in meat products, so it shouldn't have to be added. Another possibility is that the meat has been over-refined that they HAVE to add taurine to meet the requirements. Again, another good reason MEAT should be the first ingredient of your fuzzy (and feline's) food. +++ [log in to unmask] The Terrible Two and the Kitty Krew [Posted in FML issue 1486]