A few months ago my cat had a urinary blockage (crystals) so my Vet recommended Hill Prescription Diet cat food which they also sold. Recently, I looked at the ingredients and was a bit surprised at what I saw. The first ingredient was Chicken by-product meal. The second ingredient is corn gluten meal. I read some negative things about these two ingredients and was suprised they were the first two ingredients listed. I have three cats that I love very much, but the Hills cat food is very expensive and the cats go thru it quickly. Is there a cheaper commercial cat food that is recommeded for cats with urinary blockage problems?