My dog is on Hill's prescription CD

I noticed a few months back that my female spayed 3 year old seemed to have reddish urine when I saw her go outside. I worried that it might be blood in her urine, so I took a sample to the vet after making her an appointment.
Her urine had a lot of crystals in it and she had an infection he treated with antibiotics. The first 10 days of treatment didn't cure her so another vet there at the clinic prescribed a more potent antibiotic. This seemed to work, but he put her on the CD diet and said she had to be on it the rest of her life.
I wonder what sort of foods a person could give their pet if they made their own diet for the pet and also if anyone is familiar with this and has had their pet on this diet.