Stacer would you be willing to go to a Homeopath Vet? A Homeopath vet will look at the whole cat to get an understanding of not just the physical but also Angus' emotional state. They would look at the results from previous tests but won't just focus on the urinary system and may ask questions about what type of personality Angus has ie is he shy or bold, does he like warm or cold weather, is he bothered by loud noises etc - these all relate to his coping abilities. Often there is an event, minor or major, that happened at some point in their lives that we may not realize still affects them and results in different medical issues. A single or a combination of remedies would then be prescribed based on all symptoms and issues to rebalance the harmony of the system.
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food