Selenium Deficiency in Horses

Selenium Deficiency in Horses


Selenium is a mineral that is missing in our northwest soils. The only way a horse can get enough selenium in our high desert area is through supplementation or injection.


Selenium taken in conjunction with vitamin E is necessary for a proper functioning horse immune system. Horses with a deficiency in selenium will often tie-up. This is a degenerative condition of the muscles. It can affect the heart, lungs, and any other large muscle groups in the back or leg area. Mares with a selenium deficiency may have a hard time conceiving or may even have a hard time with foaling.

A horse with a selenium deficiency will cramp, be very stiff, and have an increased pulse. Also, the horse's urine will be very discolored, almost looking like coffee. To be sure your horse has a selenium deficiency, have your vet do a simple blood test.


There are many types of selenium horse supplements on the market. Zamzows has a trace mineral with selenium added 50-pound block. We also carry a loose horse vitamin supplement with selenium. Both are great on a free-choice basis. The recommended rate of selenium supplementation for your horse is 1 mg. per day, per horse. Some supplements can go as high as 2 to 3 mg per day, but much more than that can lead to problems.