Feline kidney disease is highly common in senior cats, with estimates of up to 35% prevalence in cats above the age of 12 presenting to referral canters. There are several possible etiologies for renal disease including pyelonephritis, urinary tract obstruction, toxins, hereditary disease, and nutrition. Recently, several studies documented that renal injury and a decrease in renal function can occur as a result of high dietary phosphorous (above 3.6 grams per 1000 kilocalories), particularly when the calcium to phosphorous ratio is lower than 0.9. These new findings indicate a need for new cat food regulations to set a maximum for phosphorous content, as well as an acceptable calcium to phosphorous ratio; however, the current content of phosphorous and calcium in commercially available cat food is unknown. The aims of the current proposal are to sample commercially available adult maintenance cat foods and to analyze them for calcium and phosphorous content, with the goal of evaluating if phosphorus content exceeds 3.6 g/10000 kilocalories, and whether certain formats of food such as canned, dry, grain-free, or raw products are higher (or lower) in their phosphorous content, and the calcium to phosphorous ratio. For this purpose, 60-100 cat food samples will be purchased from local retail stores or online, and sent to analysis. Correlations between food format and the aforementioned variables will be statistically evaluated.