Q&A: Understanding selenium deficiency

  • Q. I keep my horses on the Welsh borders. We’re always being told this area is deficient in selenium and many horseowners are feeding a selenium supplement. Why is selenium so important for horses when it’s needed in such small amounts?

    Christine Smy replies: Selenium is a trace element and horses only require milligrams in their diet. It is essential in animal and plant metabolism but there are selenium deficient areas in the UK.

    Selenium is present in all grains and hays but the levels depend on the amount of selenium in the soil on which they were grown.

    It is essential for:

    • Immunity
    • Growth of youngstock
    • Reproduction
    • Producing antioxidants which, when working in conjunction with vitamin E, protect the body from damage.

    If your horse isn’t getting enough selenium, he may suffer with problems such as tying up. Infections and wounds may take longer to heal and muscular cramping and muscle degeneration may also be apparent.

    Many vets recommend selenium and vitamin E is fed to a horse proneto tying up. This can help but tying up has many causes and these should also be addressed.

    Take care if feeding a selenium supplement. Selenium is toxic in high levels causing apparent blindness, staggering, colic or even death. If high levels are fed over a long period of time, chronic poisoning may be apparent in loss of mane and tail hair and separation of the hoof wall from the foot at the coronary band.

    If you’re feeding 3-4kg (7-9lb) a day of good quality concentrate, you should be providing your horse with adequate selenium levels.

    Many people feed a selenium and vitamin E supplement plus a broad spectrum supplement which also contains selenium. If this is the case, speak to a nutritionist to see if you are exceeding recommended levels of selenium in the diet.

    Read more equine supplement advice:

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