Iron in Perspective
Because excess iron cannot be excreted, there is concern that many horses suffer from iron over-load.
When you have pasture analysed, iron readings tend to be high, usually made higher by soil contamination on the sample. This is virtually impossible to avoid as is the ingestion of excess iron by the horse whilst he is grazing short grass.
Although it varies regionally, soil is inherently high in iron** so the shorter the grass, the higher the iron intake because of the close proximity of the mouth to the ground.
The iron levels in the attached graph have been obtained from Forage Analyses done by Calm Healthy Horses and clearly shows how short grass (< 2”) contains the highest iron levels by far. Long grass (> 8”) has lower iron levels and hay even lower.
The Daily Requirement, for a 500kg horse, according to the NRC Nutrient Requirements of Horses, is 400mgs/day (500 for horses in intense work, 625 for lactating mares. Horses living on short grass have an iron intake which far higher than the Daily Requirement. Water which is high in iron can also be another underestimated source.
The GOOD NEWS is that, because this iron isn’t in a bio-available form, most of it does not get absorbed anyway. Around 80-85% goes through the digestive system and out with the manure.
The iron that is absorbed by the horse is particularly important for optimal health. It is an essential element for the production of blood, for the transport of oxygen plus other roles such as assisting enzymes to perform the trillions of chemical reactions needed for life to go on.
If you are concerned about iron overload, the most effective remedial action you can take is to manage your horse’s grazing in such a way they are not living 24/7 on short grass. Having a high hay diet reduces iron intake substantially.
It is also essential to ensure optimal copper levels because copper is required for iron to perform its functions. And you need 3 x as much zinc as copper (Premium NZ Horse Minerals and Premium MVA are ideal options and take care of these ratios and everything else for your horse)
** Iron, chemical symbol Fe, is the fourth most abundant element available on Earth, according to the University of Wisconsin.
We received a question about the iron content of Himalayan salt:
“I have added Himalayan salt to my EMS pony’s feed for nearly two years, but recently someone said that it is high in iron, is this correct?”
A good question.
Even though it is the iron in the salt that gives Himalayan salt its ‘pink’ colour it contains only 0.0369mgs per gram (there are 1,000mgs in a gram) – certainly nothing to worry about. Doing the sums: in 20gms (approx. a tablespoon) there is 0.738mgs which is still less than 1mg - a truly miniscule amount.
It would be therefore be misleading to say that it is 'high' in iron.
(Table salt contains less iron at 0.0101mgs per gram. 20 gms contains 0.202 mgs of iron)
Himalayan salt used to be sea salt hundreds of millions of years ago. Himalayan salt appeals because it is subjected to minimal processing, a comparatively unrefined product with no additives. The natural harvesting process leaves the pink Himalayan salt with many other minerals and trace elements that are not found in regular table salt (99 % NaCl). These very minerals, especially the iron, that give Himalayan salt its characteristic pink colour.
The important point is that none of these trace minerals are present in large enough quantities to be of any use at all for physiological processes.
What about Table Salt?
This salt is usually highly refined — meaning that it’s finely ground, with most of its impurities and trace minerals removed. The problem is that once ground to such tiny crystals, it becomes ‘hygroscopic’ - it tends to absorb moisture from the air and clump (cake) together. For this reason, anti-caking agents, included at extremely low levels are added so that it flows freely.
Sea Salt is naturally produced when shallow ponds and bays dry up in dry, low rainfall regions, leaving the salt crystals behind where the salty water once was.
Table Salt is made via salt ‘brines’. Water is pumped into salt deposits below the earth’s surface to dissolve the salt and make a brine. The brine is pumped back up to the surface where it is processed to remove impurities.
This is how the very white free-flowing very clean ‘table salt’ is produced.
1. Salt mined on a very large scale (using dynamite) is destined for industrial purposes
• Table salt is ‘purified’ but contains anti-caking agents.
• Himalayan, other Gourmet, salts and sea-salts do not contain anti-caking agents but may contain impurities`
• They all contain minute, negligible traces of iron
Remember salt is best added to the horses feed rather than relying on a salt lick from which they do not lick sufficient quantities to meet daily requirements.
Below: Salt was an important part of transforming 'Mandy' from a poorly nourished thoroughbred back to optimal health!
Constant nibbling on short grass contributes the most iron to the diet of most horses.
What a difference in just 3 weeks when this horse was fed a properly formulated product (Premium MVA) which promotes the healthy ratios between iron: copper: Zinc: Manganese.
IRONING THINGS OUT
The iron content of the horse’s diet has become a subject of great concern but Does EVERYBODY need to worry?
Here are our CHH findings to date:
The largest source of iron in the horse’s diet comes from the consumption of short, green grass. The closer to the ground the horse is grazing, the higher the iron intake due to soil contamination.
Fortunately horses are endowed with sophisticated mechanisms in order to regulate iron absorption. Otherwise they would not have survived as a species.
These mechanisms ensure that the more iron is ingested, the LESS is absorbed. This works very efficiently in normal, healthy horses.**
Problems can arise when one or more steps in the regulatory processes of iron homeostasis are compromised.
This is why Cornell University state that iron readings should NEVER (and they emphasise the word NEVER) be interpreted on their own but ALWAYS as an adjunct to a Complete Blood Count.
Reference Ranges are actually hard to find. Cornell University have a Transferrin Saturation range of 27% – 56%. Gribbles don’t have a range on their results.
Out of interest : Horses who drank iron laden water on a property for 9 years had a Transferrin Saturation of >80%. These horses also had chronic liver disease.***
Note: random variation in iron levels is NORMAL - iron values vary widely within and between hours or days in any single individual.
The point is that normal healthy horses have no trouble with ‘excess’ iron in their diet so whilst all owners should be aware, not all need be concerned about the iron content of this feed or that, even less so the iron content of items like Himalayan salt.
Some owners are being warned off feeds or gut health products that can actually be very beneficial for many normal, healthy horses. An example is beet which although it contains iron, it also has other advantages for horses prone to, or suffering from, ulcers. I have personally spoken to very experienced people who report that ‘ulcer’ issues in their entire string of racehorses were completely solved (and their wallet saved) by the addition of a double-handful of soaked beet to those horse’s daily feeds.
Owners of horses with ‘pre-existing’ health conditions, particularly those with EMS, Cushing’s, or any form of Insulin Dysregulation are those who potentially need to be more careful and strict. Reducing or eliminating short, green grass intake and increasing hay in the diet of these horses is a useful thing to do health-wise for preventing episodes of laminitis and mitigating any tendency towards iron overload.
Iron stores in the body are actually needed for recycling of iron when required eg after acute blood loss from traumatic injury or chronic blood loss from parasite burden or ulcers.
Where possible the horse’s diet should be fortified with chelated copper and zinc****. As far as balancing copper/zinc to iron intake – yes it is possible to add up iron intake from forage and feeds but knowing how much of that iron is actually being absorbed from the food into the bloodstream to work out ratios is another matter.
The take home message is that whilst everybody should be mindful of iron intake - Optimal health shows up in coat and hoof quality so if your horse has a shiny coat, strong, robust hooves and is not over-weight or have EMS then most likely you don’t need to worry about iron over-load or which form of salt you are adding.
If you do have cause for concern then focus on the items that contribute the most in the way of iron to your horses diet and modify those (eg feed less short grass, more hay)
Water that is high in iron is more of a concern and steps should be taken to provide a lower iron alternative like rain-water to prevent problems arising in the future.
Many people are attributing ‘symptoms’ their horses are exhibiting to iron overload which have nothing to do with iron overload.
Here are the signs which MAY be associated:
• Poor coat condition – Bleaching and red ends on dark manes and tails. The coat could also have frizzy ends. These signs can usually be resolved by feeding salt plus high spec minerals as in Premium Horse Minerals, Premium MVA or Supreme Vit & Min in Australia – all now zero iron.
• EMS, Insulin issues, Cushing’s******
• Fatigue/Allergies/immune system issues – general malaise, frequent infections/abscesses.
**Effect of oral administration of excessive iron in adult ponies
Erwin G. Pearson, DVM, MS, DACVIM, and Claire B. Andreasen, DVM, PhD, DACVP
In this study 4 ponies received 50 mg of iron/kg (estimated 25 x normal consumption) of body weight each day by oral administration of ferrous sulfate for 8 weeks.....Adverse clinical signs or histologic lesions in the liver were not detected in any ponies. At 28 weeks, hepatic iron concentrations had decreased.
***Theelen MJP et al. Chronic iron overload causing haemochromatosis and hepatopathy in 21 horses and one donkey. Eq Vet J. 2019; 51: 304-309.
****Ideal ratios Iron: Zinc: Manganese : Copper -- 4: 4: 4: 1. From Dr Kellon normal, healthy horses can tolerate ratios much higher in iron10:4:4:1
******Possible dysmetabolic hyperferritinemia in hyperinsulinemic horses
Eleanor M. Kellon* and Kathleen M. Gustafson