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Coat Fading - Understanding Causes & Tips for Prevention

One of the things Friesians are most admired for is their striking black coat, and when it comes to Friesians- the blacker, the better. According to the KFPS breeding goal, Friesians should have a “jet black” coat, and horses are judged on this characteristic. Some Friesians stay jet-black year-round, whereas others experience coat fading, much to the dismay of their owners. So, why do some Friesians’ coats fade and others do not? The answer is likely due to one or a combination of three primary factors: nutrition, environment, and genetics.


To explore the factors associated with coat fading, it is important to understand a little more about your horse’s coat. Each hair in your horse's coat has three distinct layers.

The outer layer is called the cuticle. It is composed of colorless cells, called scales, which are arranged in an overlaying fashion that looks similar to shingles on the roof of a house. Think of the cuticle as the armor for the hair. Its job is to be the first line of defense for the inner layers of the hair. Although hair itself is lifeless, it's moisturized by skin oils. The sebaceous gland, connected to the hair follicle, secretes skin oils. These skin oils, comprised of fatty acids, coat the outer layer of the cuticle, tightly seal it, and repel water.

The next layer is called the cortex. This layer is made of elongated cortex cells, which are tightly packed into bundles of fibers. The cortex contains a pigment called melanin (also found in the skin) which gives the hair its color. The principal purpose of melanin is to protect the hair from damaging ultraviolet (UV) radiation or sun damage. There are two basic types of melanin found in a horse’s skin and hair: pheomelanin and eumelanin. Pheomelanin, which appears yellow or reddish brown, is found predominately in the hair of chestnuts and lighter-colored horses. Eumelanin appears brown or black and is found in bay, brown, and black horses.

The final and most inner layer of the hair is called the medulla. This hollow area houses the blood vessels that feed the hair’s root.

If either the cuticle itself or the outer layer of fatty acids is compromised due to a nutritional deficiency or environmental factors, the melanin in the cortex can be exposed to ultraviolet radiation during sun exposure. Damaging ultraviolet radiation then begins to break down the melanin in the hair. This changes the way light reflects off black hair and makes the hair appear lighter or reddish brown in the case of a black horse. This type of damage is commonly referred to as sun fading or sun bleaching. Once the UV radiation has occurred and the melanin has been damaged, it cannot be reversed. New, undamaged hair must grow in to replace it.


Some Friesian owners spend a fair amount of effort removing sun exposure for their horses altogether, but a few simple nutrition changes may make a significant difference in the coat’s ability to protect against UV radiation- especially for those horses that seem to fade even when they are protected from sun exposure.

There are two common mineral deficiencies in horses that affect melanin production- copper and zinc. According to the National Research Council (NRC), an 1100-pound horse at maintenance requires 100 mg of copper and 400 mg of zinc per day.

Copper is a critical element in the manufacturing of both pheomelanin (lighter melanin) and eumelanin (darker melanin). However, zinc is required to produce the darkest shades of eumelanin. Thus, a copper deficiency can cause color changes in any coat color, while a zinc deficiency is most apparent in black horses- bingo!

To further complicate the effects of a copper or zinc deficiency, high levels of magnesium or iron compete in the horse’s body for absorption. So, if a horse’s diet is adjusted to provide the ideal amount of copper and zinc, but no consideration for the amount of magnesium or iron is given, the effort may be in vain, and the resulting changes in coat color may be less than desired.

Iron, in particular, deserves additional consideration as most North American soil content is high in iron. This means most horses in North America ingest the minimum daily requirement of iron through forage and water alone. According to the NRC, an 1100-pound horse at maintenance requires no more than 400 mg of iron per day. Owners should be aware of any additional iron sources they add through grains or supplements, which may contribute to excess iron, thus affecting the horse’s ability to absorb the required amounts of copper and zinc.

So, what is a horse owner to do? First, know your forage! Some owners spend immense amounts of money on the best feeds and supplements for their horses without ever considering how it compliments their forage. Many owners might be pleasantly surprised to discover their forage meets nearly all their horse’s mineral needs minus a few minerals. In contrast, other owners may be unaware they need to provide more extensive mineral supplementation.

But how do you know what mineral levels are in your forage? Simple- have your forage analyzed. For much less than a month’s supply of many commercial supplements, you can send off a sample of your forage to be analyzed, and then you will know exactly what minerals your horses’ diet lacks. To really get to the bottom of things, having your forage analyzed may be an essential step, and there are a number of commercial services available that provide forage testing.

Next, read the labels and develop a complete picture. Many owners opt to feed commercial feeds for simplicity or additional calories. Be sure to read the ingredients list and the nutritional labels on your feed products. If you are feeding a commercial feed, you are likely adding some amount of additional iron to your horses’ diet. Not all commercial feed products list iron on their labels, so you may have to do a little extra leg work to determine how much iron you are feeding your horse. If you are feeding an additional supplement with your grains, you’ll have to add that information to the equation as well. You may discover you are overfeeding some minerals.

Determining what minerals you feed your horse between your forage, grains, and supplements can be complicated for some owners. If this process seems overwhelming, you might consider consulting with an equine nutritionist who can guide you through testing and analyzing your horse’s diet. You might discover you can save money by cutting out unneeded products from your horses’ diet.

Don’t forget the fat! Remember those fatty acids on the outer layer of the hair cuticle which seal the hair shaft and repel water? Adding fat to your horse’s diet can help provide that additional coating of protection and has the added bonus of producing a lovely shine. There are many popular options for safely adding a little fat to the diet, even for those easy keepers. The best fats contain a balance of omega-three and omega-six fatty acids.

Oils can be a good source of balanced fatty acids and are easily top-dressed over commercial horse feeds or hay pellets/cubes. Black oil sunflower seeds are also easily top-dressed and are highly palatable to most horses. Flaxseed, rice bran, and soybean meal are also effective sources of fatty acids. Additionally, there are many commercial fat-based products on the market or products that promise a shiny coat. As always, read the labels and consult with your veterinarian before making changes to your horse’s diet, particularly if the horse has an existing health condition.


Nutrition is only half the battle. Most horses will benefit significantly from a few simple steps their owners can take to ensure the hair isn’t damaged by environmental effects.

Keep the coat clean. Sweat is a significant factor in many horses that are sun-bleached. Sweat leaves a salty film that can quickly dry out the hair's protective cuticle and expose the melanin to the sun’s damaging ultraviolet radiation. Rinse off sweat after exercising your horse or at the end of those hot summer days. Dirt and mud can also wear away the hair’s natural protection. Remove any dirt that is caked onto the coat. A brisk daily currying of the coat using some good muscle will help bring the natural oils in the skin to the coat’s surface and protect the hair cuticle.

Lay off harsh shampoos and excessive bathing. Every time you bathe your horse, you risk compromising the protective cuticle or removing the layer of fatty acids on the cuticle that seals the hair shaft. If you must shampoo your horse, avoid harsh alkaline shampoos and inexpensive products like dishwashing soap. There are many products on the market that are cost-effective and specifically made for horses which won’t degrade the coat’s protective qualities. Don’t forget to condition the coat after shampooing, as this may help protect and seal the cuticle if it is compromised during shampooing.

Limit UV exposure. Many Friesian owners prefer to limit daytime exposure to the sun during the long summer months, turning out only at night to reduce coat fading. There are certain advantages to this course of action, but be aware that sweat should still be rinsed from the coat.

Consider adding UV protection. There are topical products that may provide surface protection from ultraviolet radiation. Some of these products are combined with fly sprays which are a convenient choice for many owners, and others are standalone sunscreens made specifically for horses. Be aware that these products may provide some protection but will likely not be able to penetrate and protect the entire coat. They will also need to be reapplied on a regular basis, especially after bathing. A popular option for many horse owners who prefer their horse to receive more turnout time is a fly sheet that provides added UV protection. Several manufacturers of fly sheets offer these options. These sheets may be hot in some cases, which may increase sweating, so be sure to rinse off any sweat at the end of the day.


Despite optimal nutrition and management strategies that reduce environmental damage, some Friesians may never achieve that desired jet-black color. Others, with little or no help, seem to stay a deep shade of black year-round. Why is this? The MC1R gene determines whether a horse can produce black pigment. Black ("E") is dominant to red ("e"). A Horse with the genotype "E/e" (one black and one red allele) has a black base color but can produce either black or red base offspring. Homozygous black (E/E) horses will always produce black-based offspring.

While much research is available about equine color genetics, we don’t yet know the genetic factors responsible for determining various shades of black. Most researchers agree a currently unknown genetic factor that contributes to a jet-black coat may exist, commonly referred to as a “true black.”


The cause of coat fading in black horses is most likely due to three primary issues: nutrition, environment, and genetics. While there is little one can do about a horse's genetics once it is born, owners can most certainly address their horse's nutrition to ensure it is optimal for the production of a dark coat and reduce environmental factors that damage hair by:

  • Analyze forages

  • Address mineral deficiencies in the diet, such as copper and zinc

  • Address mineral excesses in the diet, such as magnesium and iron

  • Read nutrition labels carefully and eliminate unnecessary/excess supplements

  • Add fat to the diet that is balanced in omega-three and omega-six fatty acids

  • Keep the coat clean- remove dirt and sweat daily

  • Curry the coat daily to bring natural/protective oils in the skin to the coat's surface

  • Don't bathe excessively

  • Use gentle shampoos made for horses

  • Condition the coat after shampooing to help seal and protect the hair cuticle

  • Limit UV exposure or use UV protectants such as a topical product or UV-rated fly sheet

With some work, you can put the optimal nutritional elements in place and take steps to protect your horse's coat from damage. This will help ensure your horse’s lovely dark coat sticks around well past spring. Ultimately, if you find your Friesian cannot attain that jet-black coat despite your best efforts, don’t despair. After all… they are still a magnificent Friesian, and no amount of coat fading can change that.


Equi-Analytical pasture/hay analysis:

How to Interpret You Hay Analysis Results, Getty Equine Nutrition:

FeedXL, Online Horse Nutrition Calculator:

To look up the National Research Council’s Nutrient Requirements for your horse according to its age, weight, and activity level, go to the Nation Academies website:



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