I fed dried dandelion to my gelding who urinary problems. Worked great and it's cheap.
I think the urinary system is one of those things that it’s good to have some knowledge so that you can be alerted when things aren't right. Fortunately, but urinary and kidney problems are not common in horses. The urinary system is home to many functions, including getting rid of waste via urine, maintaining correct balance of electrolytes, it helps too maintain healthy blood pressure as well as help to regulate red blood cells. The urinary system also processes vitamin D.
Here are the symptoms to watch for if the urinary system degrades:
Dribble urine (in mares you will likely see some skin irritation under the tail).
Stand stretched out to urinate.
Have smaller volumes of urine.
Be in pain when urinating - grunting, straining.
Show colic signs - wide stance, often with penis dropped for long periods of time or traditional colic signs - up and down, off feed, not drinking …
Have blood in the urine, especially after exercise.
If you saw that, don’t wait to call the Vet!
I hope this helps !! Bye