From Chronic Iron Overload to Equine Hemosiderosis

Iron storage disease also occurs in Equidae, as shown in a case series studied at the University of Utrecht.

In the Dutch polders, horses often drink from ditches that border the pastures. Two horses from this area were presented at Utrecht University with haemosiderosis and liver disease. Because they were not genetically related but came from the same stable, the vets became suspicious. They examined other animals, and indeed: All nine horses from the stable were affected, as were five of the seven other horses examined from neighboring farms. After an appeal in the media, six more animals were diagnosed: A total of 21 horses and one donkey from eight different stables suffered from liver disease and haemosiderosis.

Drinking water with a high iron content

The study included Equidae showing signs of chronic liver disease, such as jaundice, weight loss, thinning, lackluster fur, or elevated liver enzymes, and whose blood transferrin saturation was over 80 percent. A liver biopsy was taken from seven horses, seven others were pathophysiologically examined: there were histological signs of hemosiderosis.

Environmental samples revealed the ditch water as a problem. It has been the main drinking water source for most diseased horses for years. The iron concentration was between 0.74 and 72.5 mg Fe/l, from 0.3 mg Fe/l water is unsuitable for animals. Grass and soil were also checked, but here the iron content was not as high.

Nine out of 22 animals had to be euthanized. The others were doing reasonably well at the end of the study, years after diagnosis, but still had signs of chronic disease.

Years of oversupply

Mammals cannot actively excrete iron, so there is theoretically always a risk of toxicosis when ingesting larger amounts. In horses, however, only a few cases of acute iron poisoning after the consumption of iron-containing feed supplements have been found in the literature. In 2001, Pearson and Andreasen fed horses iron excess for eight weeks with no lesions found in subsequent liver biopsies. This study at the time concluded that iron poisoning in horses was unlikely. This is now refuted by the current study from Utrecht. However, the Dutch horses picked up the shoes over a much longer period, all having been kept in the same conditions for at least the last nine years.

Hemosiderosis – what to do?

Iron storage disease should therefore be ruled out in horses with chronic liver disease and access to natural water sources. Evidence of a possible excess of iron is an increased iron serum content and increased transferrin values, a reliable diagnosis is only possible with the help of a liver biopsy.

Therapy is symptomatic, the use of chelating agents is theoretically possible, but very expensive, and bloodletting is controversial. The most important measure is to identify the source of iron and to ensure that the metal does not continue to be consumed in excess. Incidentally, it is not always possible to tell whether the water contains too much iron: only Fe3+ ions are responsible for the typical orange-brown discoloration. Fe2+ ​​ions are colorless.

Frequently Asked Question

What is hemosiderosis?

Hemosiderosis refers to an excessive accumulation of iron deposits (hemosiderin) in the tissue. The organs can be damaged by iron deposits. The extent of the damage depends on the number of iron deposits in the organs.

Which organ breaks down iron?

Since iron is present in every cell of the body, a little bit of iron is lost every day through the natural shedding of the skin, with the stool, or through sweat. Since the intestine only absorbs about a tenth of the iron in food, about 10-30 mg of iron should be taken in daily.

How much iron does a horse need?

A horse’s daily iron requirement of 600 kg horse is around 480 to 630 milligrams. The requirement is higher in pregnant and lactating mares and growing young horses.

What happens if the horse has too much mineral feed?

But too many minerals are not healthy either. For example, an excess of calcium also makes the bones brittle and can lead to urinary stones. You should therefore make sure that the mineral feed for your horse supplements the feed ration.

Can you feed a horse too much hay?

Due to the excess energy, the horse puts on fat and gains weight. If the horse becomes overweight, this can lead to further health problems. Therefore, overfeeding should always be avoided.

Can hay make horses sick?

Just so much in advance: Bad hay can even make your horse ill in the long run – for various reasons. A few examples: Because it can make you fat. Because it can cause stomach and intestinal problems.

How many carrots can a horse eat a day?

If you like to feed a few more carrots, you can breathe a sigh of relief: it is recommended to feed horses a maximum of one kilo for every 100 kilos of body weight. This means that overfeeding only occurs if you feed a horse weighing 600 kilos more than six kilos of carrots – per day!

Why no oats for horses?

Oats are relatively low in gluten compared to other grains. Gluten intolerance is very rarely observed in horses. The sticky protein “gluten” can lead to inflammation of the mucous membrane of the small intestine in intestine.

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

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