I have a cat who has had urinary problems in the past.  He totally blocked 
twice , and the 3rd time he was partially blocked by bladder stones that had 
passed into his urethra.  He was passing some blood because the stones were 
sharp.  He required bladder surgery to get them out.  A few of the stones 
remained in the bladder, and the rest of them were in the urethra.
Summer