My dog is not passing urine. Bladder and kidney normal on ultra sound. On metacam and trimacare with no effect after 4 days. Had to have her catheterised last night. What else could b e causing her not to pass urine please. Don't think she has had bowels open for 2 days.

Kidney failure is the first thing that comes to mind for me. If not that then the bladder is not working... (and I know that you said that its normal on the ultra sound.. ).

Metacam is a pain killer, no?

I would recommend, since you've already done the ulta sound, to get x-rays..

I'm no vet or tech...