Many horse owners are misinformed or don’t know about selenium deficiency

A couple months ago, FOX 12′s Kimberly Maus lost her horse to a serious health issue she didn’t even know she could prevent.
Published: Jun. 14, 2022 at 6:48 AM PDT
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WASHINGTON COUNTY, Ore. (KPTV) - A couple months ago, FOX 12′s Kimberly Maus lost her horse to a serious health issue she didn’t even know she could prevent. Maus said she quickly learned that many horse owners don’t know about it or are misinformed.

Maverick was a stout and seemingly healthy 22-year-old horse. But on March 14, some very unhealthy symptoms appeared. He had trouble drinking water, he couldn’t chew hay and dropped his food.

The diagnosis: selenium deficiency.

“So, selenium is a critical antioxidant substance in the blood, in the body,” said Dr. Erica McKenzie. “So, when horses are deficient in selenium, their cells are prone to what we call oxidative damage.”

That damage can lead to the wasting of the limb muscles, the heart and the cheeks.

“It’s quite common for this large muscle right here, the masseter, to be damaged and also this muscle up here called the temporalis, and these are critical muscles for chewing,” Dr. McKenzie explained.

Dr. McKenzie is a teaching professor of Large Animal Internal Medicine at Oregon State University and one of the foremost veterinarian authorities on nutrition and muscle disease.

She said horses should get selenium from hay but that the land, the soil, across Oregon, Washington and California is deficient in that mineral. So the hay that comes from it is too. That’s why a supplement is key.

“It’s most important that owners are aware that they don’t need to provide much selenium, but it’s absolutely critical that they do, and that deficiency is very serious and often not reversible if we don’t catch it in time,” Dr. McKenzie said.

A minimum of one milligram a day is all a horse needs.

Sadly, Dr. McKenzie said symptoms of selenium deficiency don’t arise until the problem is severe.

“It can happen rapidly and it can happen slowly, and we don’t understand why some horses show one path and other horses show the other path,” she said.

Maverick spent 14 days in the hospital hooked up to IV’s and being fed by a tube. There were moments of hope, but his muscle loss and scarring in his cheeks and throat were ultimately too severe and it was determined he would not recover.

Maus made the heartbreaking decision to say goodbye to Maverick.


Posted by Kimberly Maus, FOX 12 Oregon on Friday, April 1, 2022

Maus said she learned many veterinarians aren’t even aware of this issue, or the need to prevent it. Selenium supplements come in the form of powder or pellets.

Some people offer a selenium salt block, thinking that is enough, but you may be surprised to find it can sometimes have the opposite effect. To hear what Dr. McKenzie says about that, watch the video below.