Re: Farriers formula and iron overload

Nancy C

I have an iron overloaded horse so it's near and dear to my heart.  I want to stay away from supplements/products that add iron and manganese.  But there is the contamination issue as well.

Kathleen is right in that most circles do not agree that non-food iron is available to the horse. We often hear that from hay, beet pulp and supplement suppliers. This would usually be from contamination - ie certainly dirt and possibly processing.

Dr Kellon had a great post on bioavilability of non-food iron that I will post in entirety. Here's the link for those of you who store these things.  :-)


--- In EquineCushings@..., "pposey09" <pposey@...> wrote:

> His response was: Iron picked up on hay analysis is in part due to
> contamination. It is iron oxide and it is not absorbed.

The next time someone tells you that, ask them what the source of that information is.

The horse is not a human or rat. Their digestive system is very different. Horses constantly secrete stomach acid and even iron oxide is soluble in their stomachs. The solubility of various iron forms in water is not a valid estimation of their bioavailability to a horse.

Pelleted diets containing high levels of iron contamination from the processing equipment and/or high iron contamination in calcium sources (basically rust or dirt, iron oxide) are well known to cause iron overload in in simple stomached, hind gut fermenting (like the horse) zoo animal species:


That study concentrates on dietary tannins in the natural diet blocking iron absorption, but we also know from other animals that when hind gut fermentation is increased, iron absorption increases.

Even in young foals that may not have peak fermentation capacity, dirt is an important iron source and being deprived of it causes iron deficiency anemia:


The same thing is seen in pigs raised on concrete.

The statement that high iron is not a problem for most horses also has no basis in fact - i.e. studies. In Dr. Smith's initial studies on iron status, 28% of horses from a slaughter sample were iron overloaded:

The health implications of this are not known because it has never been studied. That's not the same thing as saying they don't exist. For example, arthritis is the most common consequence of iron overload in people. More relevant here is that insulin resistant horses are very prone to iron overload. See study in the files.

Eleanor in PA
EC Co-owner
Feb 2001

Availability of non-food iron is why we say rinse/soak/rinse beet pulp.  Why Speedi Beet is generally higher in iron than BP shreds. Why we tell folks with excessively high iron hay to rinse it before feeding.

Knowing what is in your diet, in how large an amount and balancing excess and deficiency is key. I've kept Dr Kellon's previous post on Farrier's Formula complete as well.

FACT: Iron overload has been identified as a significant factor in IR horses that are not receiving a mineral-balanced diet. (Nielsen, BD, Vick, MM, Dennis, PM, 2012. A potential link between insulin resistance and iron overload disorder in browsing rhinoceroses investigated through the use of an equine model. J Zoo Wildl Med. 2012 Sep;43(3 Suppl):S61-5.)
See  E. M. Kellon, VMD, Iron Overload and Insulin Resistance, 2013 NO Laminitis! Proceedings, Equine Cushing's and Insulin Resistance Group Inc.


---In EquineCushings@..., <drkellon@...> wrote :

--In EquineCushings@..., <kerry.isherwood@...> wrote :

I don't think Farrier's Formula contains iron. 
= = = = = = = = =

It doesn't contain added iron but there will be iron present from the alfalfa, possibly from processing into a pellet as well.  I'm sure there is iron in California Trace also because of its ingredients (hulls and rice bran can be very high).

If it's going to be palatable, the supplement has to have a real food base so will always have iron, just not added iron.

What really matters too is the actual amount.  Something could be 500 ppm iron but 2 oz of it would only supply 28.4 mg of iron.  A pound of even very well rinsed beet pulp will have 90 to 100 mg and we all know how variable hay is.

If the horse is known to be IR or iron overloaded it is always good to know the iron in everything you feed and factor it in but in reality with something like a supplement by the time you balance tightly to the high iron in most hays the amount supplied by the supplement won't make much difference.

Eleanor in PA
EC Co-owner
Feb 2001

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