Azoturia/Tying-up Syndrome
Jim Hamilton, DVM

Tying-up or azoturia is a muscle metabolism problem. The causes
are several but the result is the same, muscle cramping. If the
cramping is severe enough then the myoglobin released from the
damaged muscle goes from blood to kidneys and into the urine,
turning the urine a dark red color. Most cases of tying-up are
not that severe and usually present as a horse that has been off
for several days and is then exercised aggressively. In the
middle of the ride (or sometimes right at the end) the horse's
stride shortens and he cramps up.

Treatment is usually routine in that anti-inflammatories, small
doses of sedative, muscle relaxers and in some cases IV fluid
therapy gets the job done. The horse is then put on a very low
energy diet for at least 1 week and blood muscle enzyme levels
are obtained to assess the damage. The bigger challenge is to
figure out why it happened and to prevent it.

One of the more common causes of azoturia in mares is the
hormonal effect of coming into heat (estrus). I have seen many
young athletic mares who are on a good nutritional and exercise
program tie-up only because they were in heat. In fact, this past
weekend we had a large driving competition here in Southern Pines
and a mare that was part of a two horse team came into flaming
heat on the day of the endurance phase. She was very fir and on a
good nutritional program but shortly after completing cross
country, she had a severe episode of azoturia.

Some of the other common causes are too high a level of protein
and energy in the diet and poor electrolytic supplementation in
hot weather.

Prevention involves use of potassium salt and baking soda
supplementation in the feed, making sure that dietary energy and
protein levels are not too high and that you be aware of
predisposing factors such as estrus in your mare or a lameness
that is overlooked. Last but not least, you will have fewer
problems in general if the horse is kept on a "regular"
consistent exercise program.