They put Hazel on this for her bladder.

Cosequin is also given to help a cat's bladder. The inner lining of the bladder wall is protected by a layer, which contains some of the same compounds as are found in cartilage. This layer prevents urine and the waste products contained within it from seeping into and damaging the lining. Since the components of Cosequin are available to more than just cartilage cells, the bladder may use them to help support this protective layer. Since Hazel had blood in her urine, they prescribed this to see if it helps.