Sorry for the delay - just got home (vets then hospital with friend's mom admitted). The ER vet catheterized Rocco, did an abdominal x-ray, and expressed his anal glands. Nothing found at all...she even said the catheter went in "smooth as butter" so there wasn't likely anything being blocked. The drained urine is being sent for testing and culture, but did not have blood or appear to have any crystals in it. They are also doing fecal testing. HERE'S the real stumper (and best part): Rocco was immediately peeing better and feeling better after the vet's. As a matter of fact, he now CANNOT HOLD IT when he's asking to go out...some spills out at the door then he goes out and does the same thing - lifts his leg several times with nothing coming out except the first time.
I'll wait to hear the test results tomorrow and Tuesday. Very relieved to this point, but I realize we're not out of the woods yet. Thank you for your warm wishes, it's sincererly appreciated after such an awful week.