More About Iron
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 while 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, 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.
Signs which MAY be associated with Iron Overload
• 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 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