This arises through chemical, mechanical, and specific causes.

To the first class belong certain drugs; to the second, stone; whilst the third class includes the germs of distemper, blood-poisoning, etc., and the extension of inflammation from adjacent parts.

It may also occur as the sequel to an operation for stone in this organ.

The urine is passed in drops, and the dog is in considerable pain, more so when the parts in this region are pressed. It is generally fatal.