Just did some looking online about the specifics on the food I feed my kitties.

This is straight from the company's website...

The diet has been specifically designed to help address the major risk factors that affect young neutered male and female cats: struvite urolithiasis and weight gain associated with neutering.

Increases urine volume to simultaneously reduce the saturation of urine with calcium oxalate and struvite, helping to prevent the two major types of urolithiasis

Recommended for:

Neutered male and female cats from operation to 7 years of age
To help prevent struvite and calcium oxalate urolithiasis
To help reduce the risk of obesity associated with neutering
Multi-cat households from operation to 7 years of age

Ok so NOW I know why the vet said it probably wasn't the food. He didn't explain why he didn't think it was the food but he already knows which food I'm feeding. I'm already feeding something to help prevent urinary problems and stones. Somehow I didn't remember seeing that part when I did the research before giving this food. Apparently I have to remember I'm not the one with the veterinary degree, he is. lol