They are not the best quality pet food. They give a lot of money to vet schools and supply the vet practices with lots of free samples. Ask the vet if he would feed it to his own dog.
There are better quality foods, but they are pricey...but considering what you are paying for Science Diet, they may not be that much more.
The only actual food in that is egg white and pork liver.
Ingredients:
Water, egg white, corn starch, pork liver, chicken fat (preserved with mixed tocopherols, and citric acid), sucrose, flaxseed, dried whey, chicken liver flavor, caramel color, taurine, minerals (calcium carbonate, calcium sulfate, potassium chloride, magnesium oxide, salt, ferrous sulfate, zinc oxide, copper sulfate, manganous oxide, calcium iodate, sodium selenite), beta-carotene, vitamins (choline chloride, vitamin D3 supplement, vitamin E supplement, ascorbic acid (a source of vitamin C), thiamine mononitrate, niacin, calcium pantothenate, pyridoxine hydrochloride, riboflavin, folic acid, biotin, vitamin B12 supplement).
http://www.hillspet.nl/adult/products/product.aspx?pid=89&packform=Can&sc_lang=en-GB_________________________________________________________________________________________________________________________________
http://www.pet-grub.com/pet-health/chronic-renal-failure.pets