Two experts weigh in on how iron may affect laminitis in horses

I contacted Dr. Thomas Divers at Cornell University by email on Dec. 9, 2011, asking what iron tests to conduct on my horses.

I chose Dr. Divers because he published a study called “Diagnosis and Treatment of Liver Disease,” in which he said: “Although iron has frequently been blamed as a toxic cause of liver failure in horses, it is not well documented.” I also had run into him briefly at the laminitis conference in Florida in 2007. He’s a well-known laminitis researcher.

He responded very quickly and gave me some suggestions for testing the horses, but he also included the comment that horses in studies have been fed very high, or 10 times the normal, amounts of iron for at least two years with no evidence of liver disease or other related problems. I took that as skepticism of my theory that elevated iron leads to insulin resistance and laminitis.

At first I was heartbroken, because I need an enemy, something to blame for losing so many horses to laminitis. If it’s not iron, then what? But, I haven’t given up on iron. For one thing, it took longer than two years for most of my horses to founder at my farm. For another, it just makes sense. If you look at all the ill effects of iron in humans, they line up perfectly with what my horses have gone through.

So, I reached out to Dr. Juliet Getty, a retired university professor and an internationally respected equine nutritionist and consultant who wrote the book “Feed Your Horse Like a Horse.” I have referenced it in earlier posts after being able to view some of the pages on Google Books. If I ever get a little spare money, I’m buying that book; she really explains things well.

I asked her in an email why she thought iron might play a role in laminitis, and she responded that she had pursued the theory after a client thought that iron played a role in a case. She said she was unable to find significant research in horses but there was plenty in humans and that research has led her to be reluctant to add more iron to the diet of a horse already getting plenty from forage.

She said iron in soil generally is poorly absorbed, but iron absorption increases in an acidic environment, such as if the horse is getting grain. Iron in supplements is more readily absorbed.

And, another interesting point: If a horse is not getting a lot of forage and standing for hours with no food in its digestive tract, the acid buildup can lead to increased iron absorption. This is bad news for every owner of a laminitic horse, including me, who has drastically cut back the hay of a horse who just foundered.

She said the bottom line is to “feed forage 24/7, avoid starchy feeds and do not feed any supplements that contain iron.”

With my horses’ low calorie needs, that 24/7 directive seems impossible. I’d love to hire her someday to help me with what my horses really should be eating every day, but I think the book is a more attainable goal.

I am grateful to Drs. Divers and Getty for responding so quickly. If only I were a scientist with a pocket full of cash and could get to the bottom of this mystery on my own.

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