Mythbuster Monday: A Copper Deficiency Can Bleach Black Horses’ Coats

On Mythbuster Monday, we tackle a variety of equestrian myths to either bust or confirm. Today’s discussion: If a black horse’s coat sun bleaches, it’s actually a copper deficiency.

It’s Mythbuster Monday, where Horse Nation dives into different equestrian myths and provides research-based evidence to either bust or confirm those myths. Today’s topic: If a dark horse’s coat sun bleaches it’s actually a copper deficiency.  How does copper deficiency show in horses? What can cause a sudden deficiency in copper? Read further to find out!

Myth: If back horse coats are sun bleached they have a copper deficiency

Myth or Fact: Fact

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A “true black” horse has more pigmentation in their its and coat that horses that aren’t black. The extra melanin makes it harder for the black color to absorb any light. To be sure your horse is a “true black,” it must undergo genetic testing. This testing will look for at least one copy of the extension (E) gene along with the Agouti gene. These genes influence how much light the coat and skin can absorb.

But, if the coat lightens at all in these horses, is it due to sun bleaching or a copper deficiency?

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According to an article by The Horse, the enzyme responsible for pigmentation, tyrosinase, is copper-dependent. Depigmentation of a true black horse’s coat indicates low copper levels. The black coat begins to have a rust looking color to it.

The most common reason for a copper deficiency is a change in copper levels in the forage the horse is consuming. Most forage contains relatively low copper amounts. To ensure your horse is obtaining the correct amount of copper, make sure to supplement essential minerals daily. The best way to do this is by providing your horse with a fortified feed. If this is difficult for your feeding regimen, many individuals add paprika to their horse’s feed to ensure optimal copper uptake.

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SmartPak published a YouTube video discussing copper deficiency. A true black horse’s coat will “sun bleach” if there is a deficiency. According to this video, copper is essential for melanin synthesis. This video also discusses how the enzymes used to create color depend on copper to do so. If there’s not enough copper to make the enzymes, the coat will first begin to look dull and muted. For true black horses specifically, the tips of the mane will be the first place you’ll notice the copper deficiency. This will be the first area on the horse to turn rust colored.

The sun bleaching part comes because the horse is not producing the enzymes to make pigmentation. A lack of pigmentation means that UV light can damage the coat further. Sun bleaching is directly related to a copper deficiency. There cannot be sun bleaching if the horse has optimal levels of copper to keep color pigmentation.

Holistic Horseworks broadcast a podcast on the “sun bleaching” of a horse’s coat.  They state that a black horse’s coat is especially hard to keep black in the summer due to copper deficiency being more prevalent in the warmer months when the grass dries out from the heat. They again reiterate that the black hues in the coat are due to copper creating the melanin in the body. One of the biggest reasons they say a horse may have a copper deficiency is worms. If a horse has not had a fecal or been dewormed recently, it’s best to start there. This is because you could give a copper supplement but the horse may not be able to absorb it.

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After diving into the literature, a true black horse’s coat does sun bleach due to copper deficiency. The two are directly related to each other. If your horse is starting to sun bleach, first check for worms or diagnose the cause before treating with a mineral supplement.

Do you have an equine myth you’d like us to tackle? If so, send it our way! Email your suggestions to [email protected]. Put Mythbuster Monday in your subject line.