> I've been waiting for my friend Linda (ChacoL) to respond to this, but I
> think she must be out of town. Here is what I recall of her experience.
> She had a horse a few years ago who had dark urine with no indications of
> tying up. I think he was ultimately diagnosed as having kidney stones that
> were causing blood in the urine.
Oops, not paying attention.
Indeed, Nick started developing dark urine during moderate exercise, or even
after a lengthy trailer ride. Most often it was brighter red, indicating
blood rather than myoglobin. Blood tests showed absolutely no metabolic
changes. He had no other symptoms. This did "stump the experts" for some
time while I managed him as if he had a mild tying-up condition--i.e.,
frequent exercise, no sweet feed--without any change in the condition.
Eventually we took him to UC-Davis where an ultrasound of his kidneys revealed
stones. I learned this is not uncommon among western horses fed largely on
alfalfa. However, they usually die of other causes before the stones become
large enough to create symptoms. In Nick's case, his kidneys were found to be
about 10 cm. in diameter smaller than the average for horses his size, which
may explain why the stones were a problem in this 10-year-old gelding.
Since the horse in question did have "metabolic mayhem," kidney stones do not