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Post reviewed Sept. 13, 2026. It became clear to me after I wrote this post originally that it would be impossible for me to test hay before I bought it to determine the iron level. I’ve given up trying to control the iron in the hay. But I definitely continue to filter iron out of the water as much as possible. My current horse, Kurt, 30, had to switch from a forage balancer to Purina Equine Senior for his teeth in 2025. In 2026, he also needs the Senior to keep weight on. He gets eight cups a day for a total iron level of 239.5 mg. 

Many owners of laminitic horses test their hay to ensure the sugar levels are low.

I found out in winter 2016 that the mineral levels in the hay and feed are equally important, and I hadn’t been looking at those.

Let me say up front that I am not a person who pushes myself to do math. But horse owners need to do just that, since feed and hay providers generally don’t provide the detailed information we need to feed our horses properly.

Both my horses looked awful in December. They were sweating profusely, and their hair was far too long and thick, even for Connemara horses and ponies in winter. Kurt looked as if he would pass out at any minute. The temperature dipped to zero a couple of times, and both horses were still sweating. I’ve never seen that in 20 years of dealing with laminitis. They fit the classic description of horses with Cushing’s disease. And, of course, this affected their feet. I kept the horses upright, but their feet looked as bad as their hair.

The one interesting factor in that development was they didn’t look like that 30 days earlier.

Robin colicked for three days Nov. 7 to 9, 2016. It was not an impaction colic; he was eating, drinking, and eliminating waste normally. But the colic (discomfort when eating) came with a very high fever of 105.4 degrees. My vet came out Nov. 9 to look at him. We reached no conclusions on the cause of the colic. Robin returned to relative normalness in three days after taking banamine orally for those three days.

At any rate, the vet saw both horses Nov. 9, and they were not sweaty furballs ready to pass out.

If I had asked the vet to come back in December, she would have said, “What changed to cause this?”

What changed was a new load of hay delivered Nov. 9 by my regular hay provider (my sixth hay provider over the last 20 years). The horses had been eating a second cutting of hay prior to that, and they hated it. The hay provider switched back to the first cutting of hay Nov. 9.

Nothing else changed.

In late December, I bought a different source of hay from the local feed store and fed the same amount. The horses immediately stopped sweating and shrank in size by February. I won’t say they lost weight, because no Connemara loses weight in that short period of time. I think inflammation was reduced. But the horses appeared smaller, and Kurt’s hair started falling out in chunks in January and February.

I tested the earlier hay from the hay provider (through Equi-Analytical), and the sugar and starch levels were very low. I selected a test (“Equi-Tech” option on the form) that included the mineral levels. The iron level was 52 milligrams per pound of hay (mg/lb), or 114 milligrams per kilogram (mg/kg). That doesn’t sound like a lot until one does a little math.

The National Research Council, part of the U.S. National Institutes of Health, provides a list of “Nutrient Requirements of Horses” along with a calculator.

The NRC recommends 400 mg of iron per day for a 500 kg (1,100 pound) adult horse on maintenance feed (click the “Other Nutrients” link at the top of the calculator). A kilogram is 2.2 pounds.

The Alberta Agriculture and Forestry Service says the NRC recommendations are the minimum levels one should provide.

The toxic threshold for iron in horses is generally listed as 500 mg/kg (Juliet Getty Ph.D., Eleanor Blazer).

Unfortunately, that’s a ratio of iron to feed. It’s not a maximum total.

I generally give the horses as much hay as they want, based on equine nutritionist Juliet Getty’s theory that horses will eat less and be much happier if they have hay in front of them all day. When they start trashing the hay, I give less.

If my horses were given an estimated eight flakes of hay a day (3.75 pounds each), the horses were given 30 pounds of hay a day and 1,560 mg of iron. It’s hard to tell what they eat when you put out a lot of hay and let them pick through it all day.

Next, I tested the Enrich Plus, a balancing feed marketed as a “low sugar, low starch formula.” One might conclude that the product is good for insulin-resistant laminitic horses. I know I did. Testing Enrich Plus cost me $54 using the “Trainer” option at Equi-Analytical, so please download the Enrich Plus results and pass them around. That’s a fair amount of money for something that should be printed on the bag, in my opinion.

The sugar level in Enrich Plus is low. But the iron level is 1,200 mg/kg, or 544 mg per pound, and each horse was getting about a pound a day.

With hay and feed, the horses’ daily iron intake totaled 2,104 mg of iron.

Since I don’t have a maximum tolerable iron total, I have to use a little logic. The horses are getting more than five times the daily recommended level of iron in their feed and hay alone. If I were eating five times the recommended amount of salt in my diet, my physician would lock me up. I’m going to conclude the horses’ iron level from two parts of their diet was unhealthy.

Getty, the nutritionist, says, “Studies have shown a direct correlation between iron intake and insulin levels in the blood, making it an important factor in managing the diet for these horses.”

What about the grass?

I didn’t have much grass to test during the winter (and testing grass requires shipping it in dry ice) so I tested the soil.

Tests on my two upper fields, where the horses hang out the most, showed the soil is very acidic, at a pH level of 4.4 (despite me adding a little lime last spring to try to get it closer to 6 or 7) and has an iron level of 797 mg/kg (mg/kg is the same as ppm). The level was marked as excessive by the testers. That level would convert to about 398 mg of iron per pound of grass.

Getty says, “Forages grown from acidic soils will be higher in iron.”

Note that I’ve been working hard since January 2016 filtering the excess iron out of the water, assuming that was the issue. All the while, the horses have been drowning in iron.

The iron level in the horses’ current hay is 31 mg per pound, and the horses don’t want as much hay now. At six flakes a day (2.1 pounds per flake), the horses are offered 403 mg of iron from the hay. They’re probably not eating that much.

I switched them to Triple Crown 30 as a forage balancer. Thank you to Triple Crown for listing the iron level on the bag and saving me another $54 in testing fees. This product has 750 mg/kg, or 341 mg per pound, of iron, and the horses are getting half a cup three times a day for a total of about 10 ounces a day and 213 mg of iron per day. It’s not zero, but better.